Dan Henderson

The All-Destroying Kant

Immanuel Kant contributed to the Enlightenment Period by introducing a Copernican Revolution in philosophy. Kant’s Transcendental Idealism, first presented in The Critique of Pure Reason, played a pivotal role in the rationalist-empiricist dialogue of the period. His counterpart, Moses Mendelssohn, referred to him as “der Alleszermalmende Kant,” or the All-Destroying Kant, because his innovations were destructive to both the empiricist and rationalist traditions. In this paper, I will explain how Kant’s methodology was so radical. I will begin with a discussion of analytic and synthetic knowledge, and then I will explain how Kant’s forms of intuition allow for synthetic a priori knowledge. Next, I will describe Kant’s argument for the permanence of substance and his argument against permanence of the soul. Finally, I will explain why I find Kant’s arguments against the rationalists and the empiricists to be convincing. I will argue that Kant’s Transcendental Idealism undermines both Hume and Descartes positions, but also preserves some important philosophical notions.

In the Prolegomena, Kant begins his critique by explaining the distinction between analytic and synthetic judgments. He states that analytic judgments “say nothing in the predicate that wasn’t already thought—though less clearly—in the concept of the subject” (Kant 7). For example, if one says that “all bodies are extended,” he or she is only making explicit what was already implicit in the concept of a body—extension. The truth value of an analytic judgment “rests wholly on the principle of noncontradiction” (7). In the case of synthetic judgments, the predicate is not already contained within the concept of the subject. For example, if one says that “a body is heavy,” then he or she adds a genuine predicate to the concept of a body. The concept of heaviness cannot be found in the definition of a body. The truth value of a synthetic judgment does not rest on the principle of noncontradiction but is usually (I will soon discuss some important exceptions) grounded in experience (8).

Also critical to this discussion are the notions of a priori and a posteriori knowledge. Kant states that a priori knowledge is based on “pure understanding and pure reason” (7). It is knowledge that is independent (but not necessarily prior to) experience. On the other hand, a posteriori knowledge is always empirical. It is gained through our senses. A priori knowledge is the kind that is necessary for metaphysics. Kant says, “The very concept of metaphysics ensures that the sources of metaphysics cannot be empirical” (7). Prior to Kant, philosophers believed that all knowledge was either analytic a priori or synthetic a posteriori, and that “never the twain shall meet.” Analytic a priori knowledge is independent of experience and applies with necessity because it is a logical truth, but knowledge of this type is destined to be trivial because these judgments are true by virtue of their definitions. Synthetic a posteriori knowledge is contingent on empirical verification and can never apply with necessity, but does provide a substantive truth about the world. Analytic a priori and synthetic a posteriori knowledge are generally considered unproblematic because they remain modest in their scope. Analytic a priori knowledge does not purport to add matters of fact to our body of knowledge but only to analyze the relations of our ideas. Synthetic a posteriori knowledge does not attempt to achieve necessity by assuming the uniformity of nature, but only to put forward contingent matters of fact (Hume 16). A third type of knowledge, synthetic a priori, is a much more contentious topic.

Synthetic a priori knowledge attempts to assert matters of fact that apply necessarily and are verified independent of experience. In the Meditations on First Philosophy, Descartes explains how he believes this to be a valid form of knowledge. He uses the example of a piece of wax to illustrate that the sensible world is understood by the intellect alone. The senses indicate that the wax is cold and firm, but when heated the wax loses the sensible qualities that we previously ascribed to it (Descartes 6). The senses now reveal the wax to be hot and liquid. Since the senses identify two distinct sets of properties, Descartes argues that we do not understand the identity of the wax by means of our senses (7). We have no direct sense of an underlying substance that endures change, so by what means do we understand the wax? Descartes considers that imagination could be responsible for this knowledge, but dismisses this hypothesis because “the wax can be extended in many more ways than I will ever bring before my imagination” (7). Having ruled out sense perception and imagination, Descartes concludes that the wax is known purely by the scrutiny of the mind alone (7). Experience only provides us with the changeable secondary qualities of the wax, but by the penetrating intellect we gain an understanding of the primary quality of the wax as an extended substance. Descartes’ understanding of the wax as an extended substance is an example of synthetic a priori knowledge. David Hume is a radical empiricist who takes critical stance against synthetic a priori knowledge.

In his Enquiry Concerning Human Understanding, Hume attacks synthetic a priori knowledge, claiming that all knowledge is intuited by the senses. Hume believes that the concepts of substance and cause and effect are fallacious inventions of habit. He argues that because there is no direct impression of either substance or cause and effect, these concepts are (literally) nonsense. He maintains that people assume, out of habit, that similar causes will be followed by similar effects. It is merely the constant conjunction of events that leads to our concept of cause and effect (Hume 16). Even if we empirically discover what we believe to be laws of nature, we cannot apply these laws to future events without assuming the uniformity of nature throughout time. In Hume’s words, “However regular the course of things has been, that fact on its own doesn’t prove that the future will also be regular” (17). Hume believes that synthetic a priori knowledge is impossible because we cannot apply our knowledge of matters of fact to future events with necessity.

Kant enters this dialogue with by taking a step back and asking, “How is metaphysics possible?” (Kant 16). For metaphysics to be possible, one must establish the possibility of synthetic a priori knowledge. Analytic a prior knowledge only results in trivialities and synthetic a posteriori knowledge is merely knowledge of physics. Kant demonstrates that mathematical judgments are one type of synthetic a priori knowledge (8). He explains that the truth values of mathematical propositions do not rest on the law of noncontradiction, but are instead found in a priori intuitions (17). According to Kant, “an intuition is the representation…that ordinarily depends directly on the presence of an object” (17). Our intuition represents things not as they are in themselves but as they appear to us, framed by human consciousness. We cannot make synthetic a priori judgments about intuitions, because they depend on experience to furnish an object. However, we can make synthetic a priori judgments using the form of sensible intuitions. The forms of the sensibility are space and time. Every sensible intuition must be mapped onto our consciousness in space and time. Part of Kant’s Copernican Revolution is the assertion that space and time are contributed “from our side of the transaction—which means that [they] can be had a priori rather than empirically” (19). To support the claim that the form of space is contributed by us, Kant gives the glove example. He demonstrates that if space was a property of things in themselves, then a left-handed and a right-handed glove could occupy the same space, because their internal relations are identical. However, in our experience, they cannot occupy the same space; a left-handed glove cannot cover a right hand (20). Kant explains that there are no differences between the gloves that can be expressed in concepts, yet they are not congruent. The gloves must be shown to be different (20). The difference between the gloves is only made comprehensible when they are intuited with respect to an observer who applies an absolute perspective. In Kant’s words, “the intrinsic nature of any region of space is fixed by how that region relates to space as a whole” (20). In this way, space is absolute and intuited. The ideality of space implies that every object of possible experience will conform to the geometer’s grid. The form of space can be used to make synthetic a priori judgments about geometry because our sensibility is hardwired to map every perception with regularity (19). Geometric truths, such as the proposition that the closest distance between any two points is a straight line, do not need to be continually verified empirically because the sensibility necessarily structures the world in that way (19). So, contrary to Hume, Kant argues in favor of synthetic a priori knowledge. Kant believes that this knowledge is limited in that it only applies to the world of appearance, but it is sufficient to establish the possibility of metaphysics.

After establishing the pure forms of the sensibility, Kant proceeds to uncover the a priori concepts of the understanding. Kant establishes the permanence of substance through the transcendental and metaphysical deductions of the categories. Kant, once again employing the analytic method, begins the transcendental deduction by asking, “what are the [necessary] conditions for experience?” (26). For Kant, judgments of experience are objectively valid. They are subjective perceptions made intelligible to every conscious being by the application of pure concepts of the understanding (27). An example of a judgment of perception would be the assertion that a stone is warm. This judgment only asserts a matter of fact about how an object affects the senses. An example of a judgment of experience would be “the sun warms the stone” (29). This statement unifies two events in time by applying the concept of causation. It asserts an objective truth about nature as the world of possible experience. Self-consciousness requires that an agent perceive objects, in space, as being distinct from herself, and also that she recognize that she affects change, through time, in her environment. The forms of the sensibility and the concepts of the understanding are the a priori software that make this possible. In the metaphysical deduction, Kant looks to logical functions to derive the pure concepts of the understanding (31). For example, a categorical proposition is a statement that predicates a quality onto a subject. This function implies that humans have an a priori concept of an underling substance to which qualities adhere. As Kant says, substance is the “subject that cannot itself be the predicate of anything else” (34). Similarly, the logical function of the conditional implies that we have an a priori concept of cause and effect (35). These two pure concepts of the understanding are essential for self-consciousness and the unification of time. In the First Analogy of Experience, Kant asserts that the concept of substance is must be permanent. He believes that we can conclude its permanence because “the understanding doesn’t draw its laws from nature, but prescribes them to nature” (40). Since our understanding uniformly applies the a priori concepts to nature, we can know that substance will underlie any object of our observation. In this way, substance is permanent. However, we can only assert the permanence of substance in the world of appearances. Concepts of the understanding cannot be applied to things in themselves because they are not objects of possible experience. This leads us to Kant’s rejection of the rationalist argument for the permanence of the soul.

Rationalists like Descartes believe that the soul is the absolute subject of consciousness of ourselves, or the ‘I’ (50). Descartes believes that the soul is a simple substance and therefore incorruptible and immortal. Furthermore, Descartes asserts this about the soul as a thing in itself. In the Paralogisms, Kant presents his argument that we cannot conclude the permanence of the soul. He attacks the claim from several angles. I will briefly present three of his arguments here. First, Kant points out that simplicity does not necessarily imply incorruptibility, unless we assume that incorruptibility is only possible by means of spatial division, and not some other means such as a “loss of intensive magnitude” (Wuerth 31, 45). Kant believes that this assumption is unwarranted. Kant’s second argument involves revealing a bad syllogism in the rationalist’s reasoning. Kant accuses the rationalists of “slipping between the two concepts of substance by means of an ambiguous middle term” (40). The syllogism proceeds as follows:

(1)What cannot be thought otherwise than as the subject does not exist otherwise than as a subject, and is therefore substance.

(2) A thinking being, considered merely as such, cannot be thought otherwise than as a subject.

(3) Therefore it also exists only as a substance. (40)

Kant argues that there is an equivocation of the term “substance.” In the major premise, it means “a being that can be thought of in every respect [including an intuition], while in the minor premise it only refers to a being capable of thought and consciousness” (40). Kant’s disambiguation reveals the faulty reasoning the rationalists use when they assert that the thinking thing is a substance. Kant’s third argument invokes his thesis of Transcendental Idealism. He explains that since the soul is a thing in itself, we cannot properly apply the concept of substance to it. The concepts of the understanding only apply to the world of possible experience. And as Kant makes very clear, “all [of] our possible experience requires us to be alive; so the only permanence-of-the-soul result we can establish is that the soul is permanent throughout one’s life” (Kant 51). So, unfortunately for the rationalists, Kant has demonstrated that claims about the permanence of the soul are not justified. However, we also cannot rule out the possibility of the permanence of the soul for the same reason— it is an unknowable thing in itself. Next I will discuss the degree to which I believe Kant’s arguments against Hume and Descartes to be convincing.

Kant’s disagreement with Hume centers on synthetic a priori knowledge. Hume failed to consider that humans apply a priori concepts to the world, rather than develop them as a posteriori habits. Hume was wary of making necessary judgments about the world because it required him to assume the uniformity of nature through time, which may be subject to future change for all we know. Kant’s Copernican Revolution allowed synthetic a priori knowledge by revealing that humans contribute the forms of sensibility and concepts of the understanding to the world of appearances. Because we play an active role in organizing nature, we can know synthetic truths about the world (for example, that the shortest distance between two points is a straight line) independent of experiencing particulars. I believe that Kant’s account is convincing, but I do have some lingering questions. For instance, how is Kant justified in asserting that humans apply the pure forms of intuition and the concepts of the understanding with uniformity? I anticipate that his response would be that the fact of self-consciousness requires that these faculties are applied with uniformity. However, this raises the question: is self-consciousness possible under any other configuration of a priori faculties? Next I will discuss why I believe Kant’s argument against the rationalists to be convincing.

Kant’s disagreement with rationalists centered on the scope of synthetic a priori knowledge. Descartes believed that the intellect could achieve genuine understanding of things in themselves, as shown in the wax passage. Kant, however, argued that objects of experience can never accurately depict the noumenal world, “for a thing’s properties cannot migrate into [a] mind” (17). Accordingly, Kant makes the distinction between the phenomenal world (world of experience or world of appearances) and the noumenal world (world removed of time and space). He concludes that synthetic a priori knowledge is possible, but only of things as they appear, not of how they are in themselves. To some, this conclusion is unsatisfying, because it says that we can never gain an understanding of the noumenal world, to others, this conclusion can be a source of hope. This leads me to my conclusion.

Kant’s Transcendental Idealism dismantles both Hume’s and Descartes’ theories. The All-Destroying Kant annihilates our understanding of things in themselves and creates a realm of the unknown. But by creating the noumenal world, Kant also preserves the possibility of the permanence of the soul and the existence of God. Paul Guyer eloquently states that “he denies knowledge in order to make room for faith” (34). This is why I believe, contrary to Mendelssohn, that Kant can be viewed as The Preserver, rather than The Destroyer.

Works Cited

Descartes, Rene. Meditations on First Philosophy. EarlyModernTexts.com. ed. Jonathan Bennett, April 2007. Web.

Guyer, Paul. Kant. Routledge: New York, New York. 2006. Print.

Hume, David. An Enquiry Concerning Human Understanding. EarlyModernTexts.com. ed. Jonathan Bennett, January 2008. Web.

Kant, Immanuel. Prolegomena to Any Future Metaphysics that can Present Itself as a Science. EarlyModernTexts.com. ed. Jonathan Bennett, April 2007. Web.

Wuerth, Julian. “The Paralogisms of Pure Reason” The Cambridge Companion to Kant’s Critique of Pure Reason. Cambridge University Press: New York, New York. 2010. Web.