Kant's Idealism and the Problem of the Thing-In-Itself
ESSAY BY BRAEDEN GIACONI
Abstract
Kant’s Transcendental Idealism, when it was first explained in the Critique of Pure Reason, immediately provoked comparisons to the idealism of George Berkeley and the skepticism of René Descartes. Kant himself was attentive about rebutting these comparisons, using both the B edition of the Critique and his Prolegomena to differentiate himself from Berkeley and Descartes. In this paper I explain Kant’s arguments against Cartesian skepticism in the Refutation of Idealism and then move to review Kant’s scattered attempts to show how he was different from Berkeley, given in the Prolegomena. I then move to considering these arguments within the wider context of Transcendental Idealism as a whole, arguing that they reveal fundamental problems with the idea of the Thing-in-Itself and display the difficulties in limiting metaphysics, the project at the core of Kant’s Critical Philosophy.
In his Prolegomena to Any Future Metaphysics, the German philosopher Immanuel Kant restates his revolutionary metaphysics from the Critique of Pure Reason. His postulating of a world in which we only know appearances and not things-in-themselves instantly created controversy and criticism when the Critique was first published in 1781. In this paper, I will argue that Kant’s discussion about the thing-in-itself in the Prolegomena results in inconsistencies and raises fundamental questions about the feasibility of the thing-in-itself in general. In doing so I aim to get to the heart of the idea of the thing-in-itself and by extension the Kantian metaphysical system as a whole. I will begin by giving a basic overview of what transcendental idealism is, and then lay out the objection that Kant’s idealism is similar to René Descartes’s skepticism, as well as Kant’s response in the Refutation of Idealism. Then I will reconstruct the objection that Kant’s idealism is similar to George Berkeley’s, and then detail how Kant responds to this.
The essence of Kant’s philosophy as it is given in the Critique of Pure Reason is a doctrine called transcendental idealism. Kant’s revolutionary position held that the conditions of experience are on the side of the individual’s cognitive structures rather than out in the world (Kant 1783/2004, 4:375). Kant places the conditions of experience in the structures of our minds. Cognition for Kant begins with the sensibility, which passively receives sensations (Kant 1783/2004, 4:318). The a priori (non-empirical) aspect of sensibility that structures the faculty of sensibility are the a priori intuitions of space and time (Kant 1783/2004, 4:291). All that is received by the sensibility will be spatial and temporal because our a priori intuitions structure the way we sense things. The other faculty necessary for cognition to Kant is the understanding, which contains concepts, the general rules by which we categorize intuitions (Kant 1783/2004, 4:300). Like intuition, understanding has an a priori aspect that structures it. The a priori form of understanding is made up of a priori concepts, which give the structure that all concepts have to take (Kant 1783/2004, 4:302). According to Kant these two faculties, intuition, and understanding make experience possible (Kant 1781/1787/2004, A50/B74). For example, if I sense a red cup, my sensibility will perceive it totally unconceptualized, but my intuition of it would be in space and time. Then the understanding with its concepts would subsume the individual intuition under the empirical concepts of cup and redness, creating the representation of a red cup. The consequence of this view is that our experience is only of appearances because we impose our cognitive structures on the world. Things without these structures are things-in-themselves, which we can’t know (Kant 1783/2004, 4:289).
Reviewers of the Critique compared Kant’s metaphysics with Descartes’s doubt about the existence of the external world from the First Meditation in his Meditations on First Philosophy. The argument of Kant’s critics at the time was that his position that we only know appearances creates a type of skepticism by preventing us from knowing the world as it is outside of our experience. Rather than his response to the comparison between his and Berkeley’s philosophy, Kant gives one comprehensive answer to his critics. In the Refutation of Idealism, which was published in 1787 in the revised B edition of the Critique of Pure Reason, Kant first defines Descartes’s skepticism as “problematic idealism”, which holds the existence of the external world to be doubtful and only our existence to be certain, and then argues that this position presupposes that the external world exists (Kant 1781/1787/2004, B275). In arguing that Cartesian skepticism actually does necessitate the external world’s existence he aims to dispel concerns that his own metaphysics leads to a similar type of doubt.
The argument of the Refutation starts with the premise that I am conscious that my existence is “determined in time” (Kant 1781/1787/2004, B275). He means that the contents of our consciousness are in a temporal order and that this order is necessary in the sense that they can’t be arranged however we like but have to be in the sequence that they are in fact in. Empirically we know that we feel ourselves having one experience after the other and that this experience is of a necessary and objective ordering. The ordering can only be objective though, Kant says, if there is something persistent throughout change to ground the time-determination of our consciousness (Kant 1781/1787/2004, B275-B276). This is because a non-subjective ordering would just be imagination: when I imagine events, I can order them in any way I like, but when events happen in time, I cannot choose their order, they happen in a necessary sequence. Kant believes that to make temporal ordering objective and thus distinct from imagination I need something that persists throughout change. The basis for the temporal ordering of my consciousness must be some persistent thing, and this is the basis for my awareness of my existence.
The persistent thing must be outside me according to Kant because my internal states are just representations that always are changing (Kant 1781/1787/2004, B275). This persistent thing outside me that grounds the time-determinations of my consciousness is substance, which could be a clock or even just my surroundings which give me something to reference the changes in my internal states to. However, the precise sense in which Kant speaks of substance here is a matter of scholarly debate insofar as Kant means substance either in the sense of interaction in the Third Analogy or in the sense of a metaphysical essence. So, I must posit the existence of something persistent that is external to me to give an objective ordering to my internal states. This means that the supposition that we are only certain of our existence but that the external world may not exist is contradictory because the former is only possible if the latter is assumed (Kant 1781/1787/2004, B276).
The result of the Refutation is that both our existence and the existence of the external world are not only linked but are made to be equally immediate (Kant 1781/1787/2004, B277). Kant’s argument establishes that the external world is in fact the condition for our inner consciousness because it is ordered in time and that as a consequence problematic idealism is impossible (Kant 1781/1787/2004, B277). It also serves the secondary purpose of differentiating Kant from Descartes and responding to the reviewers of his book who said that his view that we only know our appearances and not things-in-themselves leads to a Cartesian skepticism about the external world. In doing so Kant firmly distances himself from problematic idealism and secures his philosophy from the label of skepticism. I will not analyze Kant’s argument in the Refutation because I think he successfully differentiates himself from Descartes.
Initial reviewers of the Critique also interpreted Kant as advocating for a type of idealism similar to that of Berkeley, for whom only ideas and minds exist. They reasoned that if space is only a property of appearances and not things-in-themselves, then only our representations exist, which they thought meant that ideas rather than actual objects exist according to Kant. Kant’s interpretation of Berkeley’s metaphysics, which he called “dogmatic idealism”, was that it asserted that all perception is only of representations, which did not have a corresponding object (Kant 1781/1787/2004, B274). In response to this objection, Kant reaffirmed the distinction he makes between appearances and things-in-themselves. Rather than holding Berkeley’s view that we only experience ideas that have no object outside the idea, Kant reminds us that the world does exist apart from us according to his system, but we can’t know it because it is the thing-in-itself, that which isn’t filtered through a priori intuitions and concepts (Kant 1783/2004, 4:289). There are objects outside of us, Kant says, we just don’t know anything about them besides how they are experienced by us (Kant 1783/2004, 4:289). Still, the thing-in-itself does exist, which separates him from Berkeley, who did not posit an object that corresponds to the ideas we experience; for him, there is only appearance and no thing-in-itself.
Now I will proceed to argue that Kant’s attempt to distinguish his idealism from Berkeley’s based on things-in-themselves is unsuccessful because of Kant’s lack of a warrant to speak about things-in-themselves. On Kant’s own premises we cannot know anything about things-in-themselves or say anything about them without engaging in fruitless metaphysical speculation. Things-in-themselves, Kant says, “are not cognized at all,” (Kant 1781/1787/2004, A30/B45). In his reply to the objection that his idealism is like Berkeley’s, however, he says the following: “There are things given to us as objects of our senses existing outside us, yet we know nothing of them as they be in themselves, but are acquainted only with their appearances, that is, with the representations that they produce in us because they affect our senses,” (Kant 1783/2004, 4:289, emphasis added). Kant makes two claims in these respective quotes: first, he claims that things-in-themselves are totally unknown to us, second, he asserts that things-in-themselves affect our senses. Further, in what way is affection distinct from causation except in the plain fact that they’re different words? Any application of the category of causality to things-in-themselves is a misapplication according to Kant.
In the Critique of Practical Reason, Kant’s major work on moral philosophy, he asserted that we could have beliefs about things-in-themselves and that we can think about it without knowing it. Given that we cannot know anything about things-in-themselves, Kant’s philosophy gives us two choices: we can either believe that things-in-themselves are the source of our appearances, or we can claim agnosticism about it, but then Kant would be very similar to Berkeley concerning appearances. In Kant’s defense though we must remember that to Berkeley the existence of things outside of us is a “manifest repugnancy,” (Berkeley 1710/1982, Part I §23). However, insofar as this contradiction remains unresolved, the strength of Kant’s attempt to distinguish his idealism from Berkeley’s seems to fall back on his separate arguments given in the Appendix to the Prolegomena, but these are not being analyzed here.
This paper explained Immanuel Kant’s transcendental idealism and then examined the claims that his position was similar to the thought of René Descartes and George Berkeley. After reviewing Kant’s Refutation of Idealism, I concluded that his attempt to distinguish his own idealism from Descartes’s was successful. However, after reconstructing Kant’s reply to the objection that his idealism is similar to Berkeley’s I argued that Kant’s position that the thing-in-itself distinguishes his idealism from Berkeley’s is precarious because of the inconsistencies it is involved with. This may lead to the conclusion that Kant’s idealism is not quite as distinct from Berkeley’s as one would initially think. Ultimately, however, I think that the concerns that I raised in the analysis have to do with the obscurity of the very idea of the thing-in-itself. The thing-in-itself, however, revealed itself in the Critique of Practical Reason to be the key to Kant’s moral philosophy, and as such has remained an enduringly fascinating, if enigmatic, aspect of the Kantian system.
WORKS CITED
Berkeley, George, and Winkler, Kenneth. A Treatise Concerning the Principles of Human Knowledge ... Hackett Pub. Co., 1982.
Kant, Immanuel, et al. Critique of Pure Reason. Cambridge University Press, 1998.
Kant, Immanuel, and Hatfield, Gary C. Prolegomena to Any Future Metaphysics That Will Be Able to Come Forward as Science: with Selections from the Critique of Pure Reason. Cambridge University Press, 2004.
Braeden Giaconi is a sophomore at the University of Washington, majoring in Philosophy. You can reach him at braedeng@uw.edu.