Find Enlightenment

Edges, Entities and Existence
an epistemological excursion
by Carolyn Ray and Tom Radcliffe

Date: 2000-06-01
Forum: TOC Advanced Seminar 2000
Copyright: Carolyn Ray and Tom Radcliffe

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Sometimes Objectivists distinguish between "first class" and "second class" entities, as if some were metaphysically more significant, or more real, than others. We argue that, for some part of reality to be classifiable under the concept ENTITY, it is both a necessary and sufficient condition that there be a knowing subject who abstracts that part from the rest of reality by an act of selective attention. On this view, all entities are equal.

This view is in direct disagreement with Rand's contention that "metaphysically they (entities) are not all equal" (IOE, p. 273). Apparently, it is her view in at least part of the discussion portion of the second edition of Introduction to Objectivist Epistemology, that entities are unities in virtue of a uniting principle that is independent of any conscious subject’s awareness or attention. She grants entitihood to mountains, but not to piles of dirt:

Prof. B: Is a pile of dirt an entity? Or a mountain?

AR: A mountain would be a entity.

Prof. B: But it’s just a heap or pile of sand.

AR: It’s not a pile of sand, no. It’s minerals, metals, and whatever else a mountain is composed of, which are welded together in a certain form. You know how I would draw the distinction here? We call an entity that which is welded together physically and about which we can learn something, to which we can ascribe certain properties, as a whole.

But now as to a pile of dirt, we can only call it a 'pile' for convenience of identification, because there is nothing we can learn about the pile as a whole, nor does it have any particular attributes qua pile. It’s only separate entities put together with no consequent change in their status or in their aggregate potentialities (IOE, p. 268).

It is our contention that this distinction is not consistent with a fully-developed Objectivist epistemology, and that in fact the distinction requires a concession to realism with regard to universals. We shall nonetheless refer to this as "The Received Objectivist View", to be distinguished from the fully conceptualist version of Objectivism we put forward here. The primary question raised by The Received Objectivist View is:

By what standard are some entities more metaphysically significant than others?

Why is a rock a first-class entity and a pile of dirt a second-class entity? What is the standard that distinguishes, metaphysically, between piles of dirt and rocks?

Other Objectivist literature is ambiguous on the issue. In The Evidence of the Senses, David Kelley sometimes seems to take into account the subject's role in the creation of entities:

...shape perception becomes poorer away from the center of the visual field and figures cannot be distinguished clearly from the background. And in all the senses, attention can have the same affect. I may be looking directly at the conductor, but if my mind is on the music I may hardly see him, may hardly discriminate him from the background. There is a similar continuum even for objects attended to. (EOS, p. 155) [emphasis supplied]

And with the house, the structure itself, the walls, and the bricks are all in fact entities-they possess attributes and can act as units--even though we do not treat them as entities in the same act of attention (EOS, p. 167) [emphasis supplied].

In these cases he seems to acknowledge that while there is something in reality that is constitutive of entities, there is also an element of choice or context about what makes something an entity; that we are at liberty to treat or not treat some things as entities depending on our purpose. But at other times he says that some things just are entities, independently of us:

In the normal case, there are patterns in the stimulus array that are specific to the real entities around us, and allow us to discriminate them directly (EOS, pp. 168-9) [emphasis supplied].

There is common-sense support for a dichotomy between first- and second-class entities. Everyday experience appears to present us with pre-discriminated entities that we may be tempted to consider distinct from everything else, independently of a knowing subject who distinguishes. But when we look at any of these cases carefully we will see that there is no basis for the dichotomy other than the scale of human observation. While this scale itself is certainly metaphysically significant (in that it is a part of reality), and while its epistemological significance should not be underestimated, it has no metaphysical significance for anything else. In fact, to hold that the scale of human perception has metaphysical significance for other parts of reality requires at least an implicit commitment to subjectivism. And it is certainly not independent of the subject who attends. Therefore, it cannot serve as a basis for the claim that not all entities are metaphysically equal.

To understand how we form our concepts of entities, we must ask how we distinguish entities from the stuff around them. One basic premise that would seem to be indisputable is that an entity is a unity. A unity is some part of reality that is bounded by an edge. The question immediately arises,

To what in reality do we refer when we use the concept EDGE?

We argue that it refers to the results of the act of selective attention whereby the subject distinguishes some portion of reality from everything else. Because we construe all entities with edges that--whatever other metaphysical properties they may trace out--are created by the subject's attention, all entities are equal. Some are more interesting than others, but all are bounded by edges of the same type and origin.

In any discussion of concepts, there are two implicit issues to be addressed: the chronological, and the logical. These issues are introduced, in any Objective conceptual analysis, by the questions,

What aspect of human experience gives rise to concept X? (chronological)


To what in reality does concept X refer? (logical)

We begin by asking each question with regard to the concept ENTITY.

What in reality gives rise to the concept ENTITY? (chronological)

The answer to the chronological question at first seems pretty obvious: all these entities around us! We just perceive, and almost cannot help forming a concept that will include all the independently-existing bits of reality. Some parts of reality stand out as against a background, which background is the rest of reality as a sort of undifferentiated--or less-finely-differentiated--and, to some degree, unnoticed mass or pool.

When we look around, we see lots of stuff that we want to call ‘entities’: desk, books, cup, phone, computer, human beings. The basis on which we collect these disparate things under one concept is that they appear to us as separable from the stuff around them. We see them as unities having edges that surround them, encapsulate them, and make it easy to isolate them from everything else.

But what are "these entities"? Or, to put it in more conceptualist language, how did we get to the point of seeing the world in terms of entities? Having addressed the chronological genesis of the concept ENTITY, we must now ask the quite different question of logical genesis,

To what in reality does the concept ENTITY refer?

Consider the fact that there are many other things that are separable but that do not immediately appear to us as entities until we focus on them in a particular way: the drawers of a desk normally are considered by us to be mere parts of the desk--when asked to count the ‘things’ in the room, for example, most of us would count the desk but not the drawers. Even more so, a light bulb may normally be taken to be an integrated part of a lamp; yet we can unscrew the bulb, and easily count two entities. The things we at one time consider entities tend to blend back into the homogeneous background of the room when our focus is turned away from them. It is reasonable to conclude that it is not that these things are intrinsically separable that makes them entities, but that an act of conscious attention has separated them.

It is easy to confuse separability (RD: able to be discriminated and circumscribed by a conscious subject’s act of attention) with separatedness (RD: the objective property characterizing the relationship between some portion of reality and the conscious subject that has discriminated and circumscribed it--we use the nominalized adjectival form to emphasize that someone has performed the act of separation) because it is impossible to focus on something without isolating it: to notice is to distinguish; to distinguish is to draw edges; to draw edges is to pick out entities. So it may seem to us, unreflectively, that any particular piece of reality that we want to call ‘entity’ was separate--intrinsically, independently, and before we noticed it.

But to conclude that this is the case is to reverse cause and effect, in much the same way that the conceptual realist reverses cause and effect by looking for metaphysical essences to explain our use of concepts. It is the focus of a conscious subject’s attention on a given portion of reality that justifies and explains classifying that portion of reality as an entity, just as it is our active discrimination and mental integration that is the source of our concepts.

This discussion is one of the rare instances when reiterating Rand's axiom "Existence exists" is actually useful. There is not a lot we can say about existence in and of itself, independent of a conscious subject’s objective relationship with it; when we start talking about the bits that we have picked out and named, we are also implicitly discussing our categorization of those bits of existence. It is our explicit awareness of this fact, that distinguishes Objectivists from conceptual realists. How we identify, the terms of description we use, the edges we choose to see, the entities we choose to discriminate and group under general names, will depend on our purpose.

Although all these processes can be done in any way, so long as the it is the purpose of the subject to know reality, some ways of discriminating and categorizing will prove better than others.

If all this is true, then by what principle do we decide whether something is, or is not, an entity? The question itself is misleading. Our language is realist through and through, and it is easy for the most radical Objectivist to lapse into real-speak. This is not just a question of style; the realist language to which we are all exposed every day can itself confuse the unwary and lead otherwise conceptualist thought astray. So it is important to emphasize that what we are concerned with is classification, not discovery, when we are engaged in epistemological decision-making.

The real question is how we are to categorize; it is not what some portion of "really is". Therefore, the criterion by which we ought to decide whether a given part of reality can be justifiably classified as an entity, is whether it has been separated by a conscious subject from the stuff around it on the basis of some metaphysical discontinuity. The existence of a metaphysical discontinuity is a necessary condition for an edge to exist. A subject focusing on this discontinuity is a sufficient condition for an edge to exist. The core of our argument is that the act of focusing itself turns out to fulfill both the necessary and sufficient conditions.


The concept EDGE arises initially from our awareness of differences in the rate of change of the value along a given dimension of perception. For example the value of color along the wall does not stay constant, but jumps suddenly as the subject’s attention moves to the whiteboard fastened to the wall. And it is this awareness of differences in rates of changes in value along a given dimension that gives rise to the concept ENTITY. We perceive discontinuities as edges. As we notice these discontinuities, we tend to pull them together, to make one continuous edge of them, so that the area within its encompass resolves into a single unified portion of reality. It is by this means that we seem to discover entities. Entities are inside the edges.

Yet resolving portions of reality into entities is no more a process of discovery than is classification of entities under concepts or concept-formation. The division of entities into categories, and the division of reality into entities, are processes that are on a par.

A simple entity is one that appears to us as pre-discriminated from everything else. Free-standing solid objects may be classified as simple entities: we can pick them up and move them around independently of everything else. There is clearly something about them that makes them easily separable. We would not be correct, however, if we were to take this as evidence that there is something metaphysically special about such entities in and of themselves.

For example, consider a coin as opposed to a stack of coins. A coin is easily separable from everything else. But if we subject the coin to unusual circumstances well within the scale of human observation, we can make it behave as an inseparable part of larger whole. Consider a common bar trick in which a five dollar bill is placed on the mouth of a beer bottle, and a stack of coins is then placed on top of the bill. The challenge is to remove the bill while leaving the stack of coins in place on top of the bottle. A sharp pull on the bill can move it out from under the coins. In this case the stack has acted as a single entity, as something cohesive and coherent, closely internally coupled and separable from everything else. Although there are of course still the usual grounds for separating the coins from each other, nevertheless the fact that the stack stays intact draws our attention more strongly, prompting us to circumscribe the stack, rather than to circumscribe each coin.

So we classify free-standing solid objects as simple entities. But as the coin example helps to illustrate, the concepts FREE-STANDING and SOLID are context-dependent. The speed at which the forces acted exceeded the bounds of the context in which any individual coin could be considered free-standing: the frictional forces acting between the lot of them over the short time required to remove the bill made them act together in the way that a single simple entity would. In contexts involving large, uniformly applied forces over long periods of time, ordinarily solid bodies can have the characteristics of fluids. Such contexts may be found in soft-rock underground excavations, such as coal and salt mines, amongst other places. Thus, if the concepts FREE-STANDING and SOLID are context-dependent, so is the concept SIMPLE ENTITY.

None of the foregoing is intended to imply that there is anything wrong with further dividing the referents of the concept ENTITY to include a subclass of simple entities, but rather is intended to emphasize that they are simple relative to us, in the circumstances of ordinary life.

On this view, a pile of dirt is quintessentially an entity--the only difference between a pile of dirt and a rock is the strength of the forces acting between grains. A rock is held together by ionic bonds, just as human bodies are. Therefore a rock is solid relative to a human body. A pile of dirt is held together by van der Waals forces, which are much weaker than ionic bonds. On the scales of ordinary life this means that, relative to a human body, a pile of dirt is easily malleable and penetrable--you can stick your hand into it, change its shape, and so on. But while the scales of time and force encountered in everyday life are epistemologically significant to us, there is nothing metaphysically significant about them. They are our scales of measurement, and we can measure any way we like.

In rare circumstances where there is a small force acting on a large scale over a long period of time, a pile of dirt can move as a whole, just as a rock does when subject to forces on more ordinary scales. Nor is it true that a pile of dirt has no properties qua pile of dirt: the critical angle of repose of dry sediments (37 degrees) is a property of all piles of dirt, qua piles. So there is no reason to think that a rock is metaphysically more significant than a pile of dirt.

Naively, we have a clear idea of what an edge is: an edge is a sharp division between one thing and another. The edge bounding the desk has air on one side and wood on the other. There are more complex cases, however: the edge of a human body is less simple to define, as there are orifices that give access to the interior without a encountering a sharp material boundary. In these cases the openings are either small (pores, ears, etc.) or constrictable such that passage is difficult, which still provides an effective material boundary in ordinary cases.

Many of the portions of the world upon which we choose to focus are separable because they are made of a different material than the stuff around them. In such cases as these, when we investigate at levels beneath our originally-given human context of observation, we find we can draw finer distinctions, and that we can separate the material into different categories. We then draw our edge where we detect a difference in kind of molecule: on one side are atoms or molecules of one type, and on the other are atoms or molecules of another type, without any first-order chemical bonds between them.

Many of the edges we draw are based on this kind of lower-level discontinuity. But it would be wrong to conclude from this that every legitimate edge must be drawn on the basis of this kind of distinction. In general, any discontinuity or sudden change in the value along a given dimension can be the basis for drawing an edge.

For instance, scuba divers routinely encounter the thermocline, a layer of water where the temperature gradient is greater than that of the warmer layer above and colder layer below. The material properties of the water may be virtually identical across the thermocline, which can be quite sharp (it can be as little as 10 cm thick, so you can drift above it and stick your hand into the cold water below.) The sudden, large decrease in temperature over a very small increase in depth is the basis for drawing the edges of the thermocline. "Small" in this context means ‘small relative to the scale on which a subject is interested in observing.’

A human body is materially discontinuous with the air around it. The thermocline is discontinuous with the water around it. A musical note is audibly discontinuous with the silence or other sounds that come before or after it. How sharp such a discontinuity has to be to count as an edge depends on the purposes of the observer. For example, a large amount of effort in digital signal processing is aimed at producing suitable definitions of "discontinuous" according to which edges of interest will then be drawn, on the basis of the signals they produce in various detection apparatus while ignoring all other sudden variations.

Now we begin to see the implications of what we claim is a more fully Objectivist view. Some reclassification is in order, and features of the world which were previously difficult to classify fall into place easily. The concept ENTITY can be applied to other objects of attention besides just material objects. A musical note might be considered an entity, with its start and end in time being its edges.

The discontinuities considered above, and the edges created on their basis, are experienced as static. There are no extra-mental actions required to create or sustain them. Not all edges are like this. A great many are the result of continuous activity, and as soon as the activity stops the discontinuity ceases to be, and takes the edge with it. These may be called "dynamic edges"--edges created by an action.

Imagine a cell membrane, which can pinch off a piece of itself. In this case, we wind up with what we would count as two entities where we only had one before. The action results in a new discontinuity that we can detect at some level of observation. In observing it, we draw new edges that identify a new entity and a dramatically-altered old one.

But now consider a beam of light directed at a wall. Where the light hits is where we normally draw the edge of the wall. From a physicist’s point of view, however, this is where we could draw the edge of the spot of light itself: a circular volume close to the edge of the wall. The normal observer draws a two-dimensional circular edge, while the physicist can draw a three-dimensional one. The width of the circular edge can be measured against a scale of observation very different from our normal human context: the wavelength of the light. The discontinuities which prompt us to circumscribe the spot of light in just this way are caused by the continual, ever-renewed action of the light striking the wall and being scattered from it. In this case, continuous action external to the conscious subject is a necessary condition for the discontinuities; when the action stops, the discontinuities cease to exist.

Consider an ocean current-- the Gulf Stream, say. The Gulf Stream is a more or less fixed area in the Atlantic Ocean that is detectable by means of the discontinuity in the flow of water: within this location, water flows constantly between the continents from its gathering point in the Gulf of

Mexico to its dispersing point in the North Atlantic. Again, the action is a necessary condition for the existence of the discontinuities that prompt us to draw an edge and so create an entity we call "The Gulf Stream": take away either the action or the conscious subject who circumscribes that action, and you have nothing but ocean.

So some actions result in sharp variations, for a given scale of observation, that make it possible to separate one bit of reality from everything else. But observation, and separation, are cognitive processes engaged in by a conscious subject. That there be such a subject who is attending to the discontinuity and on that basis separating its insides from everything else is the second condition for the creation of an entity.

The spot of light example brings into question the coherency of the very idea of static edges. Superficially, a shadow or a spot of light looks pretty static. But we know that a beam of light is constituted of photons that are actively traveling from their source and absorbed by the surfaces they encounter. In the context of knowledge of physics and optics we can understand that the edge of a spot of light is in fact recreated every moment by the continuous activity of the stuff involved.

The examples of edges created by actions of otherwise homogeneous media are more interesting, as they raise the question of reification of actions. Can waves be justifiably classified as entities? We discriminate the phenomena we call ‘waves’ from everything else . But they can also be classified as activities of a medium. Is it legitimate to selectively attend to them as entities? To answer this question, we need to further explore the role of action in the creation of edges.

All edges that we identify, whether static or dynamic, have something in common: we identify them. To identify an edge, we must focus.. Focusing is an action.

We argue that an act of selective attention is a sufficient condition for the creation of an edge. In keeping with the basic tenants of Objectivism, then, we argue that both edges and entities are epistemological artifacts of human consciousness, not pre-existing, metaphysically separate parts of reality that we discover. In other words, neither edges nor entities have mind-independent

existence-they are objectively real, in that both mind-independent reality and the conscious subject are involved in their creation.

We argued above that for an entity to exist it is a necessary condition that there be a metaphysical discontinuity, and that it is a sufficient condition that a subject focus on some discontinuity. By focusing attention on a limited part of reality, the subject fulfills the sufficient condition as well as the necessary condition. The attention of the subject changes over a short distance, and thereby creates an edge. Thus, by simply focusing on a limited part of reality, the subject fulfills both conditions that are required to construct an entity .

Look at a blank piece of paper and focus your attention on a circle about 3 inches across in the center of it. Now use a pen to trace outline of the circle. The line you have just drawn follows the edge of an entity: the central circle of paper. In this case, the mind-independent line traces out the edge formed by the subject’s attention.

But if this is true, then, in this case at least, the source of the discontinuity that forms the basis for the edge is itself not mind-independent. The discontinuity is not something in the material, or in mind-independent, objective reality, but in our attention. And if such a mental discontinuity is sufficient to form a legitimate edge and therefore create an entity in one case, then it is sufficient to do so in all cases.

If you circumscribe a 10 cubic centimeter block of air one meter in front of you, your merely focusing on it creates an entity. There is nothing about the air itself that might cause you to pick out just that portion of air-there is no observable variation along a dimension. There is nothing but the general atmosphere, and the focusing of your attention on that region of it.

It is worth emphasizing, to head off suspicions that this thesis is subjectivist, that the concept CREATION in this context refers to processes that do not metaphysically affect mind-independent reality. Edge and entity are created in the mind. Reality is what it is, regardless of how we think about it, categorize it, or circumscribe it. And that is just the point: that the carving up of reality, whether into categories or into entities, is a purely mental process that has no extra-mental, metaphysical efficacy or significance.


On the account given here, all entities are in an important sense artificial. Without the subject there is no edge, and therefore no entity.

Absolute certainty is not available to us. What is available is certainty relative to a given context. There is an important further dimension to the context of certainty: the same facts may be available to two subjects who choose for their own purposes to focus on different discontinuities, or on the same discontinuities in different ways, which may result in different entities being created.

Take for example the well-known paradox of the Morning and Evening Star. From one perspective, we can see that very different entities are involved: the entity identified by "Morning Star" is different from the entity identified by "Evening Star" and both are different from the entity identified by "Venus". The Morning and Evening Stars are lights in the sky, discriminated from the background of the sky and distinguished from other stars by their brightness and nearness to the Sun. Venus is a ball of rock and gas in outer space. The three entities have different edges, in space and time, and depending on our purpose we can equally well use the name "Morning Star" and "Venus" for the light in the morning sky we now know is caused by sunlight reflected from the second planet from the Sun.

For a given purpose, some identifications are better than others, some edges are better than others. For some purposes, only one set of edges will do. In other cases, there will be more than one, but in any interesting case, there will be a finite, usually small set of edges that will allow the subject to fulfill the subject's purpose. Discovering ways of identifying things that fulfill the purpose of understanding and controlling reality is the purpose of science, and it is toward the problem of scientific progress that we now direct our attention.

Realists--people who believe that what is or is not an entity is a question of metaphysical reality rather than epistemological utility--face a profound problem when considering scientific progress. If concepts identify metaphysically real essences, then there must be one and only one correct way of identifying things because reality is only one way. In terms of scientific theory, this means that there must be one and only one true theory, and everything else is at best an approximation to it. The way reality is classified into entities by that theory must be true, because it reflects the entities that really, metaphysically exist, and every other way must be false. Furthermore, on this view, changes in theories and concepts in the sciences are only legitimate if they are motivated by bringing theory into ever-closer correspondence with whatever proves to be the ultimately correct theory (which is the same thing as bringing them theory into ever-close correspondence with reality as understood in terms of the ultimately correct theory.)

The problem for realists is that experience in the sciences shows that there are often several different conceptual frameworks that are almost equally good at describing reality. In electro-dynamics both the number and dimensions of the fundamental units (electric charge, dielectric strength, etc.) admit of variations. In classical mechanics both Newtonian physics (which takes forces as the cause of motion) and the mechanics of Hamilton and Lagrange (which takes energy as the cause of motion and force as a derivative quality) are equally valid. The quantum mechanics of Dirac, Heisenberg and Schroedinger are all quite different on the conceptual level. Within biology there are at least three different concepts of the taxonomic boundary of a biological species - cladistics, numerical phenetics and evolutionary taxonomy -- all of which appear to be equally valid. In the examples from physics, the use of precise mathematical language allows us to show that there is a formal equivalence between the various ways of identifying reality, but we must not let this formal equivalence blind us to the fact that the concepts involved in the different views are different.

Relativity theory is another case in point. It is well known and uncontroversial that the ether theory of Lorentz and Poincare’ accounts for all of the effects addressed by Einstein’s 1905 paper on special relativity. There was no disagreement between one theory and the data that could explain the prompt abandonment of ether in favor of relativity. Phenomena of this kind in the sciences leads to the question, "If science studies metaphysically real essences, then why doesn't the experimental data adjudicate between theories decisively?"

Traditionally, the only alternative to the kind of scientific realism described above (which is the sort of thing most scientists seem to believe) has been a more-or-less radical subjectivism, which typically claims that scientists choose the entities they see based on social, psychological or ideological factors. The difficulty such subjectivists views face is how to understand that, while the number of legitimate ways of classifying reality into entities is more than one, it is far less than the unbounded number implied by "Anything goes."

The Objectivist account, given our refinement of the concepts ENTITY and EDGE, is capable of explaining how it is that there is in general more than one good way of understanding the same facts, and yet always a small number of ways, because it explicitly includes the role of both reality and the choice of what to focus on in the creation of concepts.

The crucial difference between a conceptualist/objectivist account of scientific progress and a realist one is that realists are concerned to discover exactly how the world "really is," while conceptualists are concerned with how the world is best viewed for a given purpose.

If the subject's intent is to understand reality, then both reality and the nature of the subject impose certain constraints on the edges and entities that best fulfill that goal. On our account, scientists converge on commonly held sets of concepts because they have a common purpose: understanding reality. And because reality is a particular way, and human beings are a particular way, there are a fairly small number of ways that this can best be done, given any finite set of data. The difference between conceptualism and subjectivism is that conceptualists are committed to the notion that there is a best view for any context and purpose, and it is a view of mind-independent reality, while subjectivists reject this notion.

There are different edges that may be created by our attention, and even in a similar context there may be legitimate disagreements between scientists as to which ones are the most useful; the final context for any subject is the subject's own experiences and skills, and some individuals find certain ways of thinking easier than others. This sort of micro-variation in context accounts for the range of concepts that are preferred by individual scientists.

There are other factors that help keep the number of ways scientists view reality small. Sometimes two theories are equally good at accounting for existing data, but one makes calculation much easier (as is the case with Feynman's versus Schwinger's versions of quantum field theory); or one theory will provide more avenues for further research and discovery (the conflict between relativity and ether theory has been heavily influenced by this). In rare cases one theory will be pursued over another because it is favored by a particular granting agency, such as the Soviet government in the case of Lysenko's genetic theories; but granting agencies are considerably less pervasive and persistent than the nature of the universe and of human beings, and their attempts to guide the course of science necessarily fail over time.

In conceptualist terms, the best way to view the path of an object is one of fundamental questions of physics. This is quite different from the realist view that the fundamental question is what the path of an object "really is" or the subjectivist view that the fundamental question is agreed upon by enough scientists. Consider the historical evolution of the concept ORBIT. Changing ideas regarding planetary motion were driven as much by changes in focus as changes in observation.

Observationally, the Sun, the Moon and the stars (including the planets) move about the Earth. Because of the belief that circular motion is in some sense "perfect," the courses of the celestial bodies were held to be circles. More detailed observations resulted in disagreements between perfect circles and the actual motions, and to fix up the theory epicycles were added to the main motions. An epicycle is a small circular motion whose center travels around in the large circular motion. Using epicycles to describe the motions of the celestial bodies resulted in non-circular paths for those bodies about the Earth, but the claim was made that all the motions were "really" circular. This is an example of reifying the terms of mathematical description--of claiming not that orbital motion was best understood as a decomposition into a set of cycles and epicycles, but that there was something inherently right about doing so because such a description captured the way the motion "really is." The entities discriminated by an astronomer of this school is a circle about the Earth, and a set of epicycles that modify it.

Copernicus moved the center of motion from the Earth to the Sun, which simplified the description of motion considerably, particularly for Mars. Epicycles were still required to match the observed motions, but the entities discriminated by a Copernican were very different: circles about the sun, and epicycles that modified them.

The controversy between geo-centric and helio-centric circles dragged on for a long time because there was in fact nothing in the available data that gave very good reasons to discriminate between the two. Some types of celestial calculation were simpler in one system, some in the other. In the context of celestial navigation today a geo-centric description of planetary motion is still sometimes used for calculational convenience. To a realist, this can only be understood as an acceptable error; to a conceptualist, this is simply a matter of discriminating a different entity, which is perfectly valid in the context of the application.

This is not to say that there are not contexts where it is wrong to view the motion of the planets as being about the Earth. When Galileo observed the phases of Venus it became clear that the relative placements of Venus and the Sun in the geo-centric system was incorrect, and that Venus was passing both in front of and behind the Sun relative to Earth at different parts of its motion, which demonstrated that understanding the motion of Venus as being about the Earth rather than the Sun was impossible in the context of this knowledge. But there are still contexts where this knowledge is simply not relevant, and so we can legitimately view the motion of Venus as being about the Earth.

Tycho Brahe's detailed observations of planetary motion led Johannes Kepler to suggest non-circular motion as the basis for orbital shape. Kepler's theory described the path's of planets as ellipses about the Sun. A circle has only one degree of freedom: its radius. An ellipse has two degrees of freedom: the lengths of its two axes of symmetry. This extra degree of freedom made it possible for Kepler to fit the existing data with considerable accuracy. Because this simplified the description of motion considerably, a conceptualist would hold that Kepler was right to do this, but a realist would have a hard time defending it. Kepler's theory made it easier to calculate planetary orbits; but with sufficient effort equal precision could be had with circles and epicycles. Not until

Newton's theory of gravitation showed how we could unify our understanding of falling bodies, planetary motion and tides was there any reason that a realist might accept to prefer elliptical motions over circular ones. If high-speed computation had existed in Kepler's day, it is possible that ellipses never would have been used to describe the motion of the planets, because the marginal improvement in ease of calculation that the elliptical description produced would not have been significant, and the increased ease of calculation was the major selling-point of the new theory.

Realist accounts of the history sketched above are typically concerned with such questions as, "What is the real shape of a planetary orbit? Are planetary orbits really circles modified by epicycles? Or are they really ellipses? Do the planets really move around the Sun, or do they really move about the Earth?" Subjectivists are quick to point out that many of the improvements in our description of planetary motion are not justified by a realist standard. Until the introduction of universal gravitation as the cause of motion there was no reason for a realist to prefer elliptical motions about the Sun over circles and epicycles about the Earth.

On our account, questions about what the motion really is are empty. The motion of a planet is what it is; the interesting questions are epistemological, not metaphysical. In some contexts we can focus on the motion of a planet as being about the Earth, as is frequently done for purposes of celestial navigation. In a much broader range of contexts we can focus on it as being about the Sun. And we can equally well focus on it as a circle modified by epicycles or as an ellipse modified by tides and other perturbations. The claim that Newton (or Kepler) proved that planetary orbits are "really" elliptical is a realist claim. Newton's laws have solutions for the two-body problem that are mathematically ellipses. But this is no more grounds for claiming that orbits are really elliptical than the claim that epicycles give good agreement for the retrograde motion of Mars is grounds for claiming that its orbit is really a circle modified by epicycles.

Astronomers still use circles and epicycles to describe some aspects of celestial motion, when it suits their purposes, as in the case of Oort's description of stars about the center of a galaxy. On our view of entities, this is reasonable. It is perfectly legitimate to look at the path of a planet and see it as a composite entity, consisting of a main cycle and one or more epicycles, each of which is an entity. The main cycle may be centered on the Earth or the Sun, as convenient. It is equally legitimate to see it as a path composed of an ellipse (which is an entity) and a number of perturbations, each of which is an entity. And it is also legitimate to see the path as a single entity, the sum of all causes.

On a conceptualist view, reality is what it is, and we are free to describe it in any non-contradictory way. Experience shows that the number of non-contradictory ways will be small. Experience also shows that the number of non-contradictory ways is often more than one. One way often starts to appear much better than others when it becomes clear we can find a common description for apparently disparate phenomena, such as tides, the paths of comets, and the motion of falling bodies on Earth. One way may also start to appear much better than others when it supports ontological commitments that connect otherwise disparate phenomena; the description of planetary motion in terms of ellipses gained considerable power from the understanding that gravitational forces could be viewed as its cause.

Where does this leave us with regard to the nature of knowledge, truth, fact, and certainty? We have argued that the choices we make has a large influence on what we know. When we say that we know something, or that something is a fact, or is true or certain, it is always in the context of the choices we have made based on the purpose we have.


Implicit in all of the foregoing is a particular view of the roles of and relationship between metaphysics and epistemology. We now discuss this view explicitly.

Metaphysics looks for answers to the broadest, most general questions about reality. The Objectivist metaphysics says that we commit to temporally strong forms of the laws of non-contradiction and causality, both of which are closely tied to the law of identity: An existent is now what it is now. There is no claim about what an existent must be, what its ultimate substance or constituents must be, only that it must be what it is at the moment.

What we have said here is consistent with this view of metaphysics. Any valid identification of an entity must be in terms of some non-contradictorily defined edges. That different subjects, or the same subject at different times, might choose to focus on different features of the world and thereby create different edges, does not change the requirement of non-contradiction. Our point is simply that there can be more than one set of non-contradictory identifications for any given collection of data. Failure to recognize this fact is one of the reasons that traditional approaches to metaphysics go awry--not only in the opinion of Objectivists, but in the opinion of scientists generally. Whenever the object of physics is confused with the object of metaphysics, unjustifiable constraints on existence itself can result. It is our contention that some of Rand’s contentions regarding entities go awry in this way.

Epistemology addresses the question: What constitutes knowledge? The definition of the concept

KNOWLEDGE (RD) is identifications consistent with the laws of identity, non-contradiction and causality, made by a knowing subject whose purpose is to understand reality.

There is no identity without identification. Things are the way they are. There are metaphysical conditions that we identify. But there is no set of terms of identification that are a priori preferable to every other possible set of terms of identification. We identify things for the purpose of categorization and for the purpose of re-identification of individuals, not for the purpose of determining how they "really are" in some sense divorced from any subject.

Because we identify things by means of the edges we create by our acts of attention, and we have shown that there is in general more than one choice of edges depending on the purpose of the subject, we know that there is more than one way of identifying things. This does not mean that we can identify things any way at all. Whatever our specific purpose is, it has to be some form of "to know reality", and we have to conform to the metaphysical constraints laid out above.

There may be other constraints as well, depending on the specific purpose. For re-identification a different set of edges may be more efficient than for categorization, because we may want to focus on the peculiar features of the individual we want to re-identify rather than the features that make it an instance of a given category.


We included, in an appendix to this essay, several excerpts from the second edition of Introduction to Objectivist Epistemology to illustrate Rand’s ambiguities regarding the term ‘entity’. Here, we raise several more related issues that arise in the excerpts, with the hope of anticipating some questions and stimulating further thought. It is our conjecture that Rand’s discussions with the professors represent, not a finished system of epistemology, but rather a system in progress. If this is true, then it lends support to the contention that Objectivist epistemology is not a closed system, and that refinements and corrections are urgently needed, in addition to extensions and applications. And if the epistemology is not a closed system, then neither is the entire Objectivist philosophy.

On Entities as Material Objects:

Question 1: If, as Rand says, the term ‘one’ is the concept ‘entity,’ and this is a statement of identity, rather than a predication (which would seem to be supported by the further qualification “ ‘Entity’ means ‘one’.”), then is it the case that anything that may be counted is justifiably classified as an entity? In other words, if she really means this to be an equivalence, or an identity, then not only do we take each entity that we circumscribe to be one thing; but we can also say that we can consistently classify anything that we count as one thing, as an entity.

Question 2: And if it is the case that anything that may be counted can be classified as an entity, then it seems that there is justification for loosening or eliminating the restriction that Rand places on the concept ENTITY, such that all entities are physical objects that can exist on their own. It seems reasonable to divide the category of entities into physical entities and non-physical entities; her restrictions would then apply to some, but not all, entities. This would allow for the classification of the referents of common nouns such as ‘problem,’ ‘issue,’ ‘fictional character,’ etc., as entities, while still making sense of her other comments about entities as material objects. In other words, her own better doctrine allows for non-material entities.

On Metaphysical Vs. Epistemological Terms

Question 3: “Prof. E.” notes that “ ‘one’ and ‘many’ as concepts, are metaphysical, while ‘unit,’ as a concept, is epistemological,” and Rand agrees. This claim seems highly dubious, even ignoring the parenthetical “as concepts,” the meaning of which is unclear or at best unhelpful to the distinction attempted here. What does the claim mean? Maybe Rand and her interlocutor are attempting to fill out the view, emerging in this discussion, that the referents of the term ENTITY are material objects, while the concept UNIT refers to that which can only exist in the mind. This seems unlikely, since according to the rest of IOE, entities may be regarded as units of a concept, and those units in such a case are exactly the referents of the concept, which are entities. Or maybe the distinction is between entities, as material objects, and units, as anything that can be abstracted in thought; for example, the color of this computer can be abstracted in thought and serve as a unit for the concept GRAY. But if the latter is what is meant, then it is difficult to see why the distinction would be between metaphysical and epistemological, rather than physical and non-physical. All concepts are epistemological. All concepts are abstract and hence not in any sense metaphysical.

This issue is important for our view, because Rand’s better doctrine does not seem to make this sort of distinction-or at least, it does not make the distinction in this way. In our view, both the concept ENTITY and the concept UNIT are epistemological, in that the referents of both require the attention of a conscious subject; their referents do not have metaphysical existence independent of a conscious subject.

On Mental Entities, and Identity

Question: Rand insists on using the phrase ‘mental entity’ to refer to concepts and other aspects of cognition and psychology. Yet she also insists that “we can call them ‘mental entities’ only metaphorically or for convenience” (p. 158). She makes a similar claim about the pile of dirt: “…we can only call it a ‘pile’ for convenience of identification,

One might ask what “convenience of identification” is, if it is not identification. On our view, the identification of an entity involves circumscribing some portion of reality. Why does she not consider an identification of convenience, to be an identification? Certainly, the pile is some way; in fact, it even has something to tell us about the way it is. And again, a “mental entity” or concept is also some way, rather than no way; the concept itself has identity. What is the distinction that Rand wants to draw, by the modifier ‘convenience’? (One might also ask what else identification is for, if not for our convenience?)

Question: What does Rand mean by “the whole ground” in “The entity would be the whole ground; you delimit it and examine one square inch of it.”? Does she mean the earth’s whole crust? Just the dry part of the crust? And since she uses the measurement “square inch” rather than “cubic inch,” is she pointing to a two-dimensional objection, or a three-dimensional one?

On Distinguishability vs. Primary Existence

Question: What is the difference, in Rand’s mind, between a valley and built-in closet? Of the valley, Rand says that it is not an entity; the primary existents that make it possible are mountains, and these are entities. Of the closet, Rand says that it is an entity, because “you distinguish it from the room.” Again, we claim that Rand’s view of the closet represents her better doctrine; her view of the valley does not seem consistent with the rest of her system.


Objection 1:

Your examples of scientific progress, namely the move from epicycles to ellipses in the description of orbits, and the move from ether to relativity, don’t seem to illustrate your point. Take the case of epicycles and ellipses. Exactly the same edges and entities are being picked out at all times; but, mathematically, different constructs are being used to calculate the motion. But a mathematical construct is not the same as an edge, is it? You say that yourself in the paper. In fact, these examples seem to prove the realist point: that no matter how many different ways you can come up with to describe the phenomenon, the orbit of a planet is real, it has a real edge, and that edge is not created in the mind. It is an independent existent, and we’ve got two different ways of describing it, both of which pick out exactly the same edge, and then do calculations on it differently. So what do these examples have to do with the idea that entities and edges are creations in the mind?

Reply to Objection 1:

There are two issues raised by this objection: the difference between mathematical descriptions and edges, and the ontological status of planetary motion. The distinction between a mathematical construct and an edge is subtle: mathematics is a way of describing the world, and seeing different edges in the world requires different mathematics to describe it. To object that the different edges created by taking different views of an orbit are nothing more than different mathematical constructs is to reverse cause and effect: different mathematics is used because different edges are picked out. For example, one starts by seeing all motions created from circles, and then develops the mathematics to describe what is seen. Each epicycle is an entity, so there are many more entities involved when epicycles are used to describe the motion than when ellipses are.

The second issue raised here illustrates how easy it is to forget that all truths are contextual. The various views of planetary motion that we describe are all set in the context of Earth-bound subjects. Today we know that we can also view the motions of the planets from different standpoints. Viewed in the context of galactic dynamics, for instance, the motion of the planets is primarily about the galactic center, with their motion about the Sun being a small, irregular perturbation on this motion. It is only when we choose the context appropriately that the edges identified by “epicycle” or “ellipse” are created.

Objection 2:

Your view seems to ignore the fact of natural kinds. The old hackneyed example of whales being formerly classified as fish and now as mammals isn’t the end of the natural kind story. What about the fact that fertile offspring is only possible when produced by intra-species fertilization? What about the fact that hydrogen atoms only have one electron? We don’t make that stuff up; these are real, mind-independent entities that are exactly the same whether there’s an observer or not.

Reply to Objection 2:

The concept KIND, which refers to any set of individuals collected conceptually on the basis of similarity, arises from our ability to group individuals based on omitted measurements. The concept NATURAL KIND arises from the appearance that some entities are naturally of the same kind, that we apparently do not need to do any conscious differentiation or integration to come up with concepts like PEBBLE or HORSE. The distinction is a spurious one: what seems natural to integrate will change with context. All kinds are equal.

The examples raised in the objection are interesting in this regard. The nature and status of biological species is hotly debated. Only in a non-dimensional context (that is, at a given point in space and time) is there an unequivocal boundary between species. Because this is the context organisms are ordinarily observed in, it is easy to forget that other contexts exist. (Mayr, pp. 313 - 357) And while hydrogen atoms all have the same number of electrons (this is the definition of hydrogen) they do not all have the same number of neutrons. To a nuclear physicist, tritium (a form of hydrogen containing one proton and two neutrons) may be considered “of the same kind” as helium-3 (a form of helium containing one neutron and two protons) because both of them contain three nucleons. The chemical nature of hydrogen, as determined by the number of electrons, does not have any special metaphysical status.

Objection 3:

But, a wave either is an entity or it is an action of the medium (or it is something else). It has to have a nature, an identity. You seem to be saying that it has no identity. What about that?

Reply to Objection 3:

A conceptualist is happy to categorize a wave as either one or the other, depending on context and purpose. The claim that a wave must “really be” an entity or an action is a terrible problem for realists, because neither perspective tells the whole story. Most waves are actions of the underlying medium, but when viewed as entities they can be considered to have properties qua wave. Realists sometimes say that it is either metaphor or an error of convenience to treat a wave as an entity. We consider this a strength of our view that we don’t have to make this sort of claim: a wave is what it is, and we are free to view it in any non-contradictory way.

Objection 4:

Well, then, couldn’t it be anything at all, on your view? This sounds like subjectivism.

Reply to Objection 4:

True, a subjectivist would say it could be anything at all. The thing that distinguishes conceptualism from subjectivism in this regard is that subjectivists take the lack of a single “real” nature of the wave to mean that all identifications are equally good, whereas we, as conceptualists, recognize that understanding reality is the guiding principle of philosophy, and this limits the range of acceptable identifications. It wouldn’t make sense, for instance, to identify a wave as a brunfelsia, or as a mammal, or even as a photon, given the rest of the conceptual scheme; and recall that fitting into the rest of the conceptual hierarchy is one of the requirements.

Objection 5:

Then what counts as knowledge, on your view? It seems that, according to you, as long as I have some purpose, I can draw my edge anywhere, create an entity in my head that no one else could ever be aware of, and start deriving conclusions about it, without even the requirement that I check to see whether I’m justified in drawing such an edge. And you’d count those conclusions as knowledge. But that really does sound subjectivist, or Kantian, or something.

Reply to Objection 5:

We define knowledge to be the identifications of a subject whose purpose is to understand reality that are consistent with the laws of non-contradiction, identity and causality. On this basis, you would only be justified in drawing an edge if you were doing so for the purpose of understanding reality, and could do so in a way that did not contradict any other knowledge that was relevant in the same context. A celestial navigator who treats the motion of the Sun as being about the Earth rather than the other way around can be said to know that the Sun moves about the Earth in the very limited context of those calculations. In many other contexts, this would contradict other relevant knowledge, and so would not count as knowledge in those contexts.

When this sort of situation exists, where contradictory views may be held by the same subject in different contexts, it is necessary that the subject not forget the existence of the broader context, and never try to extend conclusions from a narrow context into a broad one.

Objection 6:

If we can create entities any way we want, then how can we tell the difference between what is real and what is unreal? How can we tell what exists and what doesn’t? Do these terms have any meaning left, on your view?

Reply to Objection 6:

These terms are still meaningful in two senses. To begin with, the concepts REAL and EXIST arise because most of our experiences occur with things outside our imaginations. Imagined objects exist, of course, as the contents of our minds. But we consider them to be in a different category than things that exist outside our minds and persist in our absence. We tell the difference between that which is real and that which is only imagined the same way that we always have.

In the second sense, things that are real and exist obey the laws of non-contradiction, identity and causality, and can be integrated into the full context of our knowledge. When we say something exists we are committing it to the care of metaphysics; we are claiming that it does not lead to any contradictions in our knowledge, or violations of the metaphysical laws. If someone were to claim that by an act of selective attention she had created an entity that was at once entirely red and not entirely red, you would know she was mistaken, because such a thing is a contradiction. But there is a stronger condition: if someone were to claim that he had found a way to make hydrogen undergo nuclear fusion using electrolysis in palladium, you would equally well know he was mistaken, because such a thing contradicts a vast range of other knowledge and requires all sorts of things-from neutrons to gamma rays-to behave in ways that they don’t.


Some quotes from Introduction to Objectivist Epistemology

“The first concepts man forms are concepts of entities-since entities are the only primary existents. (Attributes cannot exist by themselves, they are merely the characteristics of entities; motions are motions of entities; relationships are relationships among entities.)” (p. 15).

“Prof. E: Would it be fair to say that a concept qua concept is not a concrete but an integration of concretes, but qua existent it is a concrete integration, a specific mental entity in a particular mind?

AR: That’s right. But I kept saying, incidentally, that we can call them ‘mental entities’ only metaphorically or for convenience. It is a ‘something;. For instance, before you have a certain concept, that particular something doesn’t exist in your mind. When you have formed the concept of ‘concept,’ that is a mental something; it isn’t a nothing. But anything pertaining to the content of a mind always has to be treated metaphysically not as a separate existent, but only with this precondition, in effect: that it is a mental state, a mental concrete, a mental something. Actually, ‘mental something’ is the nearest to an exact identification. Because ‘entity’ does imply a physical thing. Nevertheless, since ‘something’ is too vague a term, one can use the word ‘entity,’ but only to say that it is a mental something as distinguished from other mental somethings (or from nothing). But it isn’t an entity in the primary, Aristotelian sense in which a primary substance exists.” (p. 158) [emphasis supplied]

“… the term ‘one’ is the concept ‘entity’. And the concept ‘entity’ is the base of your entire development. It has that great epistemological significance.” (p. 198)

“AR: Of course, and here is where we have to be Aristotelian: everything that exists is one. ‘Entity’ means ‘one’. But we couldn’t have the distinction between what we mean by ‘one’ vs. what we mean by ‘entity’ if we didn’t have the concept of numbers more than one….


Prof. E: Am I correct in saying that ‘one’ and ‘many,’ as concepts, are metaphysical, while ‘unit,’ as a concept, is epistemological?

AR: That’s right.” (p. 199)


Rand speaks here as though parts must be physically separated from the whole, in order to be considered entities. Parts of entities are entities-once they are separated. Note that she also says here that an entity is “that which you perceive.”

“Prof K: ….in speaking of perceptual entities, you state, ‘entities are the only primary existents.’ Now, does this imply that you grant that there is a metaphysical status of entity apart from whether or not something is a perceptual entity?

For example, is it in principle possible for a perceptual entity to be composed of constituents which are metaphysically themselves also entities, such as a brick wall with the individual bricks also retaining their status as entities?

AR: Certainly. What about human beings? Heads, arms, and legs can be cut off and they are entities….

An entity is that which you perceive and which can exist by itself. Characteristics, qualities, attributes, actions, relationships do not exist by themselves.


…parts of an entity can exist separately; but if they are separated, the entity is no longer the same kind of entity.


…if you regard a television set as an entity, then if you remove that which makes it a television set-the works-what remains is no longer a television set, even though the parts exist separately…..In that sense, you could regard parts as an attribute of a given entity-as that without which it would no longer be the same kind of entity. But, metaphysically, you must always remember that the parts can exist separately, whereas attributes and actions cannot exist apart from the entity.

Included in the very concept of attributes is the fact that they are parts which you can separate only mentally, but which cannot exist by themselves. That is the difference between ‘part’ and ‘attribute’.” (pp. 264-5)

“…If it can be separated for a split second it is a part, it is not an attribute. An attribute is that which cannot be physically separated. Now, what is an entity? It is a sum of [it is] characteristics….

….the attributes are the entity, or an entity is its attributes.” (pp. 266)


Here, Rand speaks as though the mere possibility of a part being separated is both a necessary and sufficient condition for being considered an entity:

“Prof. E: You’re not bothered at all about the fact that the mountain is not spatially separable from the earth? You don’t regard spatial separability as intrinsic to an entity?

AR: What do you mean by spatial separability?

Prof. E: The mountain is stuck to the earth.

Prof. B: So is a tree.

Prof. E: Yeah, but you could uproot a tree.

Prof. B: You could uproot a mountain, if you were strong enough.


Prof. B: But on the other hand, if you look at the earth’s surface, it is continuous-the surface goes across, and up, and down.

AR: And that which goes up is what you define as a mountain.”


And here, Rand seems to take our view: that an entity is within whatever edge you happen to draw:

AR: …It’s the same issue as inbuilt furniture in a room, like a desk which is built into the room, it doesn’t become entity-less by being attached to the wall; it’s still a separate entity, only it’s attached to the wall.

Prof. F: So is a built-in closet an entity?

AR: Yes, certainly. Because you distinguish it from the room; it’s not the room. [emphasis supplied]

Let me give you the arch-example of this type of consideration. What about a square inch of ground? Is that an entity or not? You can, from an epistemological viewpoint, regard any part of an entity as a separate entity in that context. And a square inch of ground would be just that….” [emphasis supplied]

But with the next sentence, we are back to the other view again:

“The entity would be the whole ground; you delimit it and examine one square inch of it. In the context of your examination, it’s a specific entity, that particular inch, even though metaphysically, in reality, it’s part of many, many other inches like it.”

And back again, in the next paragraph, except there is an explicit statement about physical being:

“The concept of ‘entity’ is an issue of the context in which you define your terms. So that an entity has to be a material object, but what you regard as an entity in any given statement or inquiry depends on your definitions. You can regard part of an entity as a separate entity.”


RD: real definition, provided where the concept is valid and definable

CG: chronological genesis, sometimes given in place of a real definition, especially if the concept is not definable.

LG: logical genesis, provided where the chronological genesis is different from how a philosopher should form a concept.

EX: explanation (not intended as a definition)

ATTENTION, RD: an act of conscious, deliberative awareness taken by a conscious subject whose object is to know reality. (The subject may be conscious of many things in the environment without paying attention--i.e., without deliberately attempting to gain knowledge of reality.).

SELECTIVE ATTENTION, RD: attention that is directed by some specific purpose, such as discriminating the edge of an entity. See also, FOCUS.

DISCONTINUITY, RD: a large change in the value on one dimension over the range of a small change in another dimension, where "large" and "small" are taken relative to the context of the observer.

COMPARISON, RD: an act of consciousness whereby some portion of reality is measured against another.

DIFFERENCE, CG: a concept arising from our experience of perception, from the fact that we can perceive at all.

DIMENSION: any determinate, observable feature of a given portion of reality.

EDGE, RD: a particular way of viewing a discontinuity. See also, DISCONTINUITY

ENTITY, RD: a mind-dependent creation produced by a conscious subject's focusing on some portion of reality in such a way as to proscribe an edge.

EXIST, CG: a concept that arises first from an awareness of the difference between objects of the imagination and objects in mind-independent reality, and then comes to imply that something is consistent with the laws of non-contradiction, identity and causality, and is consistent with the full context of our knowledge.

First-class entity (and second-class entity): a spurious distinction that refers to the alleged fact, disputed in this work, that some entities are more metaphysically significant or real than others.

FOCUS, RD: To deliberately direct the attention. See also, ATTENTION, SELECTIVE.

IDENTITY, CG: a concept that arises in every act of awareness, and expressing the idea that things are what they are and are some way (rather than no way).

KIND, RD: a category into which we sort the entities that we discriminate.

Logical genesis of a concept, EX: the location of a concept within the rest of the conceptual hierarchy.

Natural kind theory, RD: the metaphysical doctrine that some existents are members of kinds that are not the cognitive creations of conscious subjects. CG: arises because some entities seem to us to be perceptually pre-discriminated, independent of any input by our consciousness. See also REALISM, CONCEPTUAL.

Necessary condition, RD: a set of circumstances that must obtain if another circumstance is to obtain.

OBJECTIVE, RD: a property of the interaction between a conscious subject and reality

REAL, CG: arises as the conscious subject learns to differentiate between objective fact and unadulterated creations of the mind.

Real definition, RD: a proposition that locates a given valid concept within the wider genus to which it belongs, and differentiates it from the other species of the same genus. It will be noticed that this definition differs from traditional ones, in that the genus is not taken to indicate a metaphysically real essence, but rather to locate the concept defined within the rest of the conceptual hierarchy.

Realism, conceptual, RD: the metaphysical theory that our concepts are caused and justified by the real, metaphysically existing essences that they name. CG: arises because of an apparently natural inclination of human subjects to consider all words to be names of things, and to attempt to match every name to a real, existing entity. LG: refers to a spurious theory that takes the mere existence of names to be evidence for the existence of entities allegedly named.

Scale of observation, RD: the level of measurement of interest to (or available to) a conscious subject for a given purpose. EX: The normal scale of human observation includes that which we can perceive with our unaided perceptual apparatus. This scale is sometimes taken as an indicator of what is "real," rather than the limiting factor of what we happen to be interested in or what we are able to observe at the time. The scale of observation can also be a subset of the scale of human observation, or it can be some extension of it.

SEPARABILITY, RD: able to be discriminated and circumscribed by a conscious subject, given a particular scale of observation.

SEPARATED, RD: intentionally circumscribed by a conscious subject. CG: arises originally because some objective discontinuities appear to us as given; LG: refers to the objective property of entities whereby those entities stand out against the background of the rest of reality.

SIMILARITY, CG: arises from our awareness of degrees of difference -- that some things are less different from a given object than others.

SMALL, RD: of more limited range along a particular dimension, relative to the scale on which the subject is interested in observing.

Sufficient condition, RD: a set of circumstances that make another circumstance possible.

UNITY, RD: an object of knowledge that is treated as a single thing, bounded by an edge.

Works Cited

Kelly, David, THE EVIDENCE OF THE SENSES: a realist theory of perception (Louisiana State University Press, Baton Rouge, 1988)

Mayr, Ernst, TOWARD A NEW PHILOSOPHY OF BIOLOGY: observations of an evolutionist, (Belknap Press, Cambridge MA, 1988)

Rand, Ayn, INTRODUCTION TO OBJECTIVIST EPISTEMOLOGY, 2nd ed. (Meridian, New York, 1990) Harry Binswanger and Leonard Peikoff, eds.

Works Consulted

Locke, John, AN ESSAY CONCERNING HUMAN UNDERSTANDING, (Penguin, London, 1997) Roger Wollhouse, ed.

Kuhn, Thomas, THE STRUCTURE OF SCIENTIFIC REVOLUTIONS, 2nd ed. (University of Chicago Press, Chicago, 1970)

Newton-Smith, W.H., THE RATIONALITY OF SCIENCE (Routledge & Kegan Paul, London, 1981)

Segre’, Emilio, FROM FALLING BODIES TO RADIO WAVES: classical physicists and their discoveries, (W.H. Freeman, New York, 1984)

Segre’, Emilio, FROM X-RAYS TO QUARKS: modern physicists and their discoveries, (W.H. Freeman, New York, 1980)