Kant & the Problem of Metaphysics (23 March 2023; Kant)

    In this essay, I’ll discuss Kant’s objection to the way metaphysics has existed in philosophy, as it too frequently over-extends itself into speculation beyond the realm of possible experience, attempting to answer questions that cannot be answered. This revelation drastically changed the field of metaphysics, in defining what it cannot address. I’ll primarily reference Kant’s Prolegomena in this essay, in addition to a few references to his Critique of Pure Reasoning. First, I’ll recount how Kant calls the field of metaphysics into question, and what necessarily constitutes metaphysics. Next, I’ll specify what the problem with metaphysics is. Finally, using one of the ideas of reason as an example, I’ll further explicate the problem of metaphysics, aiming to show that Kant provides sufficient evidence that traditional metaphysics is flawed and that pure reason over-extends itself.

Kant calls the very existence of metaphysics into question early in the Prolegomena; in addressing those whose aim it is to study metaphysics, he poses the question, “‘Whether such a thing as metaphysics is at all possible?’” (Pro 225), as its history is troubled and seems to make little progress as a science, lacking a solid structure. He argues that its status as a science itself is questionable, writing that “to ask whether a science is possible presupposes doubt to its actuality… it cannot exist unless the demands expressed here on which its possibility depends are satisfied” (Pro 256). 

Having established that he aims to address the possibility of metaphysics, he delves into what exactly constitutes metaphysics itself. Metaphysics is distinct from other sciences as it concerns a priori cognition, in that it operates independently from empirical or a posteriori things: “Its principles must never be derived from experience. It must not be physical but metaphysical cognition, namely cognition lying beyond experience” (Pro 265). Metaphysics itself contains judgments pertaining to metaphysics, as well as metaphysical judgments, which he points out, are not the same. Judgments of metaphysics can be analytic, operating as axioms of metaphysical judgments, which are inherently synthetic. As to the whole of metaphysics, he says that “Generation of a priori cognition according to both intuitions and concepts, finally, also of synthetic a priori propositions in philosophical cognition in particular, constitutes the essential subject matter of metaphysics” (Pr 269). In his critique of pure reason, he clarifies this definition, writing that “Metaphysics is a speculative cognition by reason that is wholly isolated and rises entirely above being instructed by experience. It is cognition through mere concepts (not, like mathematics, cognition through the application of concepts to intuition), so that here reason is to be its own pupil” (CoPR Bxiv). What he’s saying here is that cognitions belonging to understanding give concepts pertaining to and confirmed by experience, but in metaphysics, reason appears in ideas, not experience. Given a basic understanding of what metaphysics entails, he turns towards the problem associated with it: “Is metaphysics at all possible?... this question must be answered… on the basis of a conception of a science of this kind, which is currently merely problematic” (Pr 274).

Essentially, the problem with metaphysics overextending its reach is centered around the fact that it cannot turn towards experience for validation of its judgments. He argues that those making metaphysical assertions are doing so in vain, utilizing hopelessly indefensible assumptions (at least, in the current state of the science): “You speak through pure reason and presume… to create a priori cognitions not only by dissecting given concepts but also by asserting connections which do not rest upon the principle of contradiction and which you believe you conceive quite independently of all experience, how do you discover this and how will you justify your pretensions?” (Pr 277). Cogniziation in a field which exists only in an a priori  sense leads to inherent problems, which he points out again in the Critique of Pure Reason: “our faculty of a priori cognition produces a disturbing result that seems highly detrimental to the whole purpose of metaphysics… namely, that with this faculty to cognize a priori we shall never be able to go beyond the limits of possible experience, even though doing so is precisely the most essential concern of this science” (CoPR Bxix). Though the idea of metaphysics is to draw a priori conclusions removed from experience, it faces the difficulty of not being able to go beyond the limits of possible experience. He questions any possible method of metaphysics, wondering how, when given a concept, one can go beyond that concept and synthetically connect it with another (thus making a metaphysical judgment), “that is not contained in it in such a manner as if the latter necessarily belonged to the former[.] Nothing but experience can furnish us with such connections… all cognition assumed to be a priori is nothing but a long habit of accepting something as true and hence of mistaking subjective necessity for objective” (Pr 277). Given these problems, until a solution of some sort is reached, he believes metaphysics should be put on hold until it can be discovered how synthetic a priori cognitions are even possible. In its unresolved state, metaphysicians cannot even presume what exists beyond the limits of possible experience, and can only “assume the existence of something that is possible and even indispensable for the guidance of the understanding and the will in life” (Pr 278).

After the problem has been established, Kant ventures into what is known for certain to be a priori, concluding that mathematics and natural science meet this criterion, through the usage of the a priori intuitions of space and time. Synthetic a priori knowledge must be based on space and time in order for objects to be given to us. However, space and time do not give us any of the three ideas of reason, so we cannot have synthetic a priori knowledge of any of the three ideas. Reason always searches for completeness, which leads it to mistakenly seek beyond the realm of possible experience. He claims that “Concepts of reason aim at completeness… thereby [transcending] every given experience, and [becomes] transcendent” (Pr 328). The problem with these concepts is that the objective reality of them “and the truth or falsity of metaphysical assertions cannot be discovered or confirmed by any experience” (Pr 327). Because they’re confined to the empirical realm, metaphysical judgments made by reason as synthetic a priori are non-falsifiable and invalid. Because falsity cannot be confirmed by experience, “this part of metaphysics… is precisely what constitutes its essential end” (Pr 327). Reason cannot satisfy its desire for completion because the connection between ponderance of its own concepts cannot be directly connected to objects of experience.

I’ll now venture into Kant’s ideas of reason. Reason “contains in itself the source of ideas, by which I mean necessary concepts, whose object cannot be given in any experience” (Pr 328). The lack of objectivity from experience in the ideas of reason is what constitutes reason itself as being the crucial foundation for a priori cognition to take place. The ideas “represent the idea of a complete subject, complete series of conditions, and the determination of all concepts in the idea of the complete sum of what is possible” (Pr 330). To exemplify an instance in which reason over-extends itself beyond its end, I’ll look at Kant’s dissemination of the Psychological Idea. Both the psychological and cosmological ideas begin in experience and only encounter difficulty when they try to increase their reach in pursuit of completion. He claims that pure reason demands we need a subject for every predicate (states something about the subject) of a thing. We tend to search for subjects indefinitely, delving deeper and deeper, until eventually (ideally) finding an ultimate subject which cannot be a predicate for any other subject. However, the concept of an ultimate subject cannot be conceived, as substance cannot be thought of in and of itself (Pr 333). Predicates of the inner sense refer to I as a subject, which seems to be an ultimate subject, as it is not the predicate of any other subject. This concept seems to be provable in experience as concepts from the understanding give this impression (from time). The I is not a concept, however, rather it is the thought-of object of the inner sense that happens to have no further predicate. I cannot be the predicate of any other thing and exists only as the relation of inner appearances to their unknown subject. This misunderstanding infers the nature of the I, as our knowledge of it is outside the sum of experience. Though we think the substance soul (or thinking self) is the ultimate subject of thought, permanence cannot be proved (Pr 334). The synthetic a priori proposition: “a subject not existing itself as the predicate of another thing with permanent existence,” can only be proved in reference to objects of possible experience. If the concept of the soul is to be thought as substance to its permanence, such an assertion is valid only for possible experience and not of the soul as a thing beyond all possible experience. This means we can infer the permanence of the soul only in life, as death is the end of all experience which concerns the soul as an object of experience. It is not possible for the contrary to be proved.

Thus, permanence of the soul can be proved only during life, but not after death. Because of this, the concept of substance being combined with that of permanence is only possible according to the principles of possible experience (Pr 335). The same can be said for something real existing outside of us: that fact can only correspond to our outer perceptions, and cannot be proved as a connection of things in themselves. There’s something empirical, or an appearance in space that admits a satisfactory proof. We have nothing to do with objects other than the ones that belong to possible experience. We’re conscious of the actuality of bodies in space as outer appearances through means of experience, just as we are conscious of the existence of our own soul through means of inner experience (Pr 336). The cognization of soul as an object of inner sense through appearances constituting inner sense, and the essence underlying these appearances cannot be known. Therefore, the I is the object of inner intuition and the subject of consciousness. I is also the thing itself that underlies the appearance; questioning whether bodies (outside sense) exist apart from ourselves can thus be dismissed (Pr 337). 

Essentially, the search for an ultimate subject performed by the Psychological Idea is a misguided pursuit. In order to have knowledge, each subject we think of must have a predicate. We can’t know anything about the nature of I. We frequently refer to I as the subject, but rather than existing as the ultimate subject, it is only (as aforementioned) the thought-of object of the inner sense with no further predicate attached to it. Though we are conscious of objects through the outer sense, we cannot know anything about the nature of them in and of themselves. The same is true for the soul, pertaining to inner sense rather than outer sense (time vs space). Everything we claim to know about the soul must come from the inner sense, thusly experience, so questions about the soul existing in death cannot be answered. 

Kant’s arguments clearly demonstrate the problem with metaphysics, a field which stood uncontested for too long. In his conclusion, he writes that, 

“it would be absurd for us to hope that we can cognize more of any object than belongs to the possible experience of it or lay claim to the least cognition of anything not assumed to be an object of possible experience… For how could we determine anything in this way, since time, space, and all concepts of the understanding, and especially all the concepts derived from empirical intuition or perception in the sensible world have and can have no use other than to make experience possible… if this condition is omitted from the pure concepts of the understanding, they do not determine any object and have no significance at all” (Pr 350).

Thus, any attempt to think of an object beyond possible experience is futile; we cannot even remotely form a concept of things in themselves beyond possible experience. And if no concept of experience can learn about what the soul is in and of itself, we find ourselves asking the question by assuming a concept of reason, one which “we cannot at all prove its objective reality” (Pr 352).