Can Kant's Ethics Survive His Metaphysics?
by Diana Mertz Hsieh

Date: 5 May 1995
Forum: Washington University in St-Louis, Kant and 19th Century Philosophy class
Copyright: Diana Mertz Hsieh

Section 1: Introduction

One of the explicit purposes of Kant's Copernican Turn in metaphysics was to provide a solid foundation for his ethics, and so the principles and methods of analysis laid down in Kant's metaphysics presumably serve as the indispensable premises of all of his work on ethics. By far, the most important metaphysical conclusion for Kant's system of ethics is the possibility of the freedom of the will, which is rendered possible by the dualism between the realm of experience and the realm of things in themselves of Kant's metaphysics.

Due to the dependence of Kant's ethics on his metaphysics, if any serious contradictions arise in the metaphysics, then the veracity of the ethics must also be brought into question. Indeed, such serious obstacles do exist, and they directly bear on the primary connection between metaphysics and ethics -- the possibility of the freedom of the will. The first contradiction arises in claiming that the realm of things in themselves both exists and is unknowable, for claiming that something exists is a claim to knowledge. The second contradiction is a result of the claim that the realm of things in themselves is the cause of the realm of appearances, when the law of cause and effect ought not be applied to things in themselves (because it is an a priori principle). Both of these problems pose serious threats to Kant's project in metaphysics, and thus to the entirety of his ethics.

So in this paper I wish to explore the connection between Kant's metaphysics and his ethics, in order to determine whether the contradictions in Kant's metaphysics ultimately undermine his ethics. Because of the interdependence of his system, we cannot simply divorce Kant's ethics of duty from his metaphysics, and if the metaphysics cannot serve as an adequate enough foundation, then Kant's ethics will have to be discarded until a more solid foundation can be found (if such is possible).

Section 2: Existence of the Realm of Things in Themselves

The fundamental principle of Kant's metaphysics is that the objects of awareness must conform to our mode of awareness, rather than the mode of awareness conforming to the objects, as previous philosophers had assumed. This method of analysis immediately leads to a form of dualism, in which there is one realm untouched by awareness, and other that has been molded by awareness. This worldly dualism -- the split of existence into a realm of things in themselves and a realm of appearances -- in turn necessarily implies that we cannot know anything about the realm of things in themselves, because in order to do so we would have to step outside of our means of awareness, which is impossible.

This dualism allows Kant to establish the possibility of freedom of the will, for with it he is able to assert of freedom in the noumenal realm, even though in the realm of appearances "there is no freedom, but all is nature." (Prolegomena 339) The realm of appearances is necessarily determined because the law of cause and effect is an a priori idea which applies to all possible experience. But freedom is possible in the noumenal realm, precisely because the law of cause and effect is a priori and because noumena is not constrained by the a priori concept of time, as appearances are. The possibility of freedom is the crucial connection between metaphysics and ethics, for the whole subject of ethics is irrelevant to any predetermined entity who simply reacts to outside forces. In other words, given Kant's premise that the objects of experience are completely determined, the postulation of the realm of things in themselves is a necessary requirement for any of his work in ethics.

Upon examining Kant's own derivation of these views, a gaping inconsistency arises. Although Kant does explicitly agree with this conclusion that it is contradictory to assert anything about the realm of things in themselves, he repeatedly makes unjustified claims to knowledge about the realm of things in themselves. Kant attempts to reconcile these claims by asserting that although "we cannot indeed, beyond all possible experience, form a definite notion of what things in themselves may be," that we must still speculate as to the nature of things in themselves because "experience never satisfies reason fully." (Prolegomena 351) But this claim presupposes the most fundamental claim to knowledge about the realm of things in themselves -- that it even exists.

Claiming that the realm of things in themselves exists, even while denying knowledge of any of its attributes, since it is a form of knowledge of which humans are supposed to be incapable. Since this claim about the unintelligibility of the realm of things in themselves necessarily follows from Kant's view that the objects of knowledge must conform to the means of awareness, I believe that the self-contradiction of asserting an unknowable realm of things in themselves must also lead us to question the fundamental principle of Kant's Copernican Turn.

But regardless of how much of Kant's metaphysics this contradiction overturns, it is clear that Kant cannot even arrive at the possibility of the freedom of the will without the existence of the realm of things in themselves. And without the freedom of the will, Kant cannot derive the Categorical Imperative, the central principle of his ethics.

One possible means of escaping this apriora would be to argue that just as it is not necessary to prove that the will is free once the possibility is established, it is not even necessary to prove the possibility of freedom of the will. Kant states that we do not have to prove that the will is free once we have shown its possibility, but rather just have to show that freedom is a regulatory "idea posited by all rational beings as a basis for their actions," i.e. that all rational beings must consider themselves free. (Foundations 448, note) So perhaps we don't even have to indicate how freedom of the will is possible, as long as we know that freedom is a regulatory idea that all rational beings must employ. This solution is not as effective as one might hope it to be, since a direct contradiction arises in any attempt to say that freedom and thoroughgoing determinism can exist in the same realm. Kant's demonstration that freedom is possible in the realm of things in themselves is necessary to conclude that freedom can be a regulative idea because no rational agent could operate under two contradictory principles. Thus the attempt to ignore the difficulties that arise when even the existence of the realm of things in themselves (i.e. the possible realm of freedom) is truly deemed unknowable cannot yield any fruitful results.

Another means of escaping this apriora would be to claim that the realm of things in themselves is actually knowable through Reason. But such an attempt must eventually deny Kant's dualism of world-as-processed-by-Reason and world-as-unprocessed-by-Reason, because there is no way to gain knowledge without using Reason and also employing a priori ideas, according to Kant. For example, if knowledge of whether space and time exist as things in themselves (as well as a priori ideas) were possible, it would still be impossible to discern whether any awareness of space and time as things in themselves was due to knowledge of the realm of things in themselves or was simply produced of a priori ideas. But beyond the contradictions in Kant's own system, this solution would be committing the very same errors that Kant criticizes in other philosophers -- conflating the nature of the noumenal and the phenomenal realms.

Section 3: Causality in the Realm of Things in Themselves

The particular causal relationship between the realm of things in themselves and the realm of appearances is a central principle of Kant's metaphysics, and yet it undermines his later conclusions about the law of cause and effect. Kant must assert that there is some causal relationship between these two realms because appearances are simply the product of the processing of things in themselves by a distorting consciousness. But saying that there is an actual causal relationship between these realms contradicts Kant's claim that the law of cause and effect cannot apply to things in themselves because it is an a priori principle.

It is clear from Kant's writings that he wants to avoid idealism, the view that "there are none thinking beings; in all other things we believe are perceived in intuition are nothing but representations in the thinking beings, to which no object external to them in fact corresponds." (Prolegomena 288-289) And so Kant holds that a realm of things in themselves exists, that "things as objects of our senses exist outside us, but we know nothing of what they may be in themselves, knowing only their appearances, i.e the representations which they cause in us by affecting our senses." (Prolegomena 289) Although this positions avoids idealism, it undermines the very purpose of the inquiry itself: the establishment of the universal validity of the principles of metaphysics.

Kant can only establish metaphysics as a universal science through an appeal to a priori ideas, i.e. by asserting that "the understanding does not derive its laws (a priori) from nature, but prescribes them to nature." (Prolegomena 320) And so the law of cause and effect can only be derived by appealing to the nature of Reason, which necessarily makes appearances obey the law of cause and effect. But Kant has already assumed, in saying that the realm of things in themselves causes the realm of appearances, that the law of cause and effect has a universal validity beyond the scope of human understanding, i.e. that it exists out in nature.

Kant could respond to this criticism that because his understanding is constituted in a certain fashion, he must postulate a causal relation between the noumenal and the phenomenal realms, even if there is no such relation exists. But Kant can only reach the idea that a priori ideas regulate consciousness by the whole construction of the two realms (including the connection between them), and so to argue thusly so would be using a conclusion of an argument to invalidate the very premises that the conclusion rests upon.

Kant could also circumvent this contradiction by denying that there is a causal connection between the two realms, and thus essentially denying the existence of the realm of things in themselves. But this would clearly place Kant into the idealist tradition that he is attempting to avoid, as well as give rise to the exact same problems in simply denying the existence of the realm of things in themselves, as previously discussed. Also, without some causal connection between the realm of things in themselves and the realm of appearances, the actions of the will would be totally irrelevant and ineffectual in the realm of appearances.

Section 4: Kant's Conception of the Will

Kant's conception of the will, as has been indicated previously, serves as the metaphysical foundation for all of his ethics, particularly the categorical imperative. The positive conception of the will is that it is not just lawlessness, but rather a causality of a particular kind -- autonomy, i.e. "the property of the will to be law to itself." (Foundations 447) The essential nature of the will is determined to be autonomy because it is in opposition to natural necessity, which is "a heteronomy of efficient causes." (Foundations 446) Kant then states that "the proposition that the will is a law unto itself in all its actions, however, only expresses the principle that we should act according to no other maxim than that which can also have itself as a universal law." (Foundations 447) Thus Kant establishes the basis for the Categorical Imperative, the principle that one ought never act in such a way that one could not will that the maxim of the action should be a universal law.

Kant states that the Categorical Imperative follows from a mere synthetical analysis of the concept of the freedom of the will, and that method is precisely the difficulty with Kant's grounding of the Categorical Imperative, for there is little reason to accept the conception of the will that Kant then synthesizes into his fundamental principle of morality. Certainly other coherent conceptions of the will have been proposed which do not yield the Categorical Imperative. This objection is just an application of the wider objection to innate or a priori ideas on the grounds that their existence is not necessary to explain knowledge.

In his own elaboration of the freedom of the will, Kant actually partially provides the answer to how to ground causality without resorting to a priori or innate ideas. Kant states that the will is "a kind of causality of living beings so far as they are rational," and hence that "freedom is by no means lawless." (Foundations 446) So the freedom if the will can be viewed as one type of causality, while the deterministic cause and effect of the material world is simply another. Thus to say that freedom and nature are opposed is false, for they are both variants on a wider principle of causality, which is simply the principle that an entity can only act in accordance with its nature. But regardless of which explanation of causality is correct, there is still little reason to accept Kant's particular conception of the will.

Section Five: Conclusion

The two fundamental contradictions in Kant's metaphysics -- that the realm of things in themselves exists and that it causes that the realm of appearances -- undermine the very foundation of Kant's ethics, the possibility of the freedom of the will. Given his conception of the law of cause and effect, Kant cannot move beyond the immediate contradiction of freedom in a realm where he thinks that determinism reigns. And even if we grant the possibility of freedom of the will, there are few compelling reasons to accept Kant's particular conception of it, and thus accept the Categorical Imperative as binding on all rational animals.

Thus, because of the strong connections between Kant's metaphysics and his ethics, the contradictions in Kant's metaphysics must necessarily undermine the principles of his ethics. Although it is possible that another means of grounding his ethics exists, until such a metaphysical foundation is discovered, we cannot accept the categorical Imperative as binding on the behavior of rational beings.

Works Cited

Kant, Immanuel. Prolegomena to Any Future Metaphysics. Indianapolis: Hackett Publishing Company. 1977.

Kant, Immanuel. Foundations of the Metaphysics of Morals. New York: Macmillan Publishing Company. 1990.

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