Hume and Kant: The Synthetic A Priori Problem

Illustration of analytic and synthetic statements.

Illustration of analytic and synthetic statements.

[Note: This is an old paper I wrote that still holds up.  It shows the need modern philosophy has for metaphysics and exemplarism.]

By: Jay

The famed skeptic-empiricist, David Hume (1771-1776), concluded his An Inquiry Concerning Human Understanding by declaring:

When we run over libraries, persuaded of these [his] principles, what havoc must we make? If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask; does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion.1

The arguments from Hume’s Inquiry admittedly forced Immanuel Kant to awaken from his “dogmatic slumbers” of uncritical metaphysical assumptions.2 The purpose of this paper will be to examine the reasons for these bold statements and to consider the chief epistemological and metaphysical point of contention between both philosophers.

Hume’s project is one of critical analysis. His goal is to question the assumptions philosophers had hitherto utilized in order to construct elaborate metaphysical systems. His principle example of criticism, possibly the most foundational assumption of speculative theorists in his day, is the concept of causality. Causality had been taken as a foundational axiom of reality: from Aristotle to the Schoolmen to Leibniz, causality was assumed to be a self-evident, universal, necessary law of reality.

Hume posits, however, that causality is not grounded in any rational, a priori argumentation: it is entirely unfounded. He writes,

In a word, then, every effect is a distinct event from its cause. It could not, therefore, be discovered in the cause, and the first invention or conception of it, a priori, must be entirely arbitrary. And even after it is suggested, the conjunction of it with the cause must appear entirely arbitrary; since there are always many other effects, which, to reason, must seem fully as consistent and natural. In vain, therefore, should we pretend to determine any single event, or infer any cause or effect, without the assistance of observation and experience.3

There is no basis in experience for one event following necessarily upon another, Hume argues, and thus causality cannot be rationally justified. In other words, no contradiction is involved in denying the supposed necessity of causality; but a statement’s denial is what proves it to be necessary, if the denial results in a manifest contradiction. Thus, because there is no contradiction involved in denying the supposed necessity of causality, its denial does not amount to a contradiction. If no contradiction is involved in denying the necessity of causality, then causality is not a priori.

If causality is not a priori, Hume thinks our belief in the necessary connection between two events must be a posteriori, and therefore a product, not of rational justification, but of psychological custom or habit. As Runes’ Dictionary of Philosophy notes,

As knowledge [for Hume] consists in relations of ideas in virtue of resemblance, and as the only relation which involves the connection of different existences and the inference of one existent from another is that of cause and effect, and as there is no resemblance necessary between cause and effect, causal inference is in no case experientially or formally certifiable…the necessity of causal connection must be explained psychologically.4

Hume can then declare, “that the sun will not rise tomorrow is no less intelligible a proposition, and implies no more contradiction than the affirmation, that it will rise.”5 Causality and similar believed-to-be a priori maxims had been the very foundation upon which previous metaphysics and foundationalist epistemology had relied: without a priori judgments of experience, metaphysics as a science would appear impossible. It is this apparently irresolvable dilemma which drove Hume to declare that the volumes of the speculators and schoolmen are only worthy of flames. Metaphysics, for Hume, is an impossibility, which landed him in full skepticism. Further, Hume’s removal of the previously assumed inductive and causal principles seemed to destroy the rational justification for doing natural science: it is here that Kant picked up the issue, seeking to save science.

Immanuel Kant, as mentioned, was awakened by Hume’s critique somewhat late in life and began a project he would title a “Copernican revolution” in philosophy. Kant would seek to solve the problem of metaphysics by constructing his system of critical or transcendental idealism by which the pitfalls of skepticism could be avoided. He restates Hume’s question in a more formal fashion by asking how are synthetic a priori judgments possible? That is, how are a priori statements that contain expansive information about experience not contained in the subject itself, justifiably held to be universal and necessary? Following Hume’s devastating critique, Kant admits they appear to be impossible: it is here that Kant proposes a brilliant solution to Hume’s question.

Rather than considering causality as an organizing principle of nature, something metaphysical, causality is a universally and necessarily existing category, imposed by the mind upon reality. As such, it is a precondition for the intelligibility of experience. Synthetic a priori judgments are shown to be rationally justified by the fact that they are preconditions for intelligibility. Kant writes,

“This is, therefore, the result of all our foregoing inquiries: ‘All synthetic principles a priori are nothing more than principles of possible experience’ and can never be referred to things in themselves, but only to appearances as objects of experience. And hence pure mathematics as well as pure natural science can never be referred to anything more than mere appearances, and can only represent either than which makes experience in general possible, or else that which, as it is derived from these principles must always be capable of being represented in some possible experience.”

In other words, certain mental categories must characterize objects of experience for the entirety of one’s experience to be coherent. These a priori intuitions, such as space and time, for example, are presupposed in any knowledge-act, and are demonstrated by being principles of all possible experience. To deny the pure intuitions of space, time, and/or causality would be to make experience unintelligible.

In this way, then, Kant believes he has found a method for the natural sciences, which utilize metaphysical assumptions, to be saved from Hume’s devastating critique. Where Hume had offered only a negative criticism without any attempt at solving the issue, Kant posits a solution. The question that remains is whether Kant’s answer is entirely sufficient: while providing undoubtedly brilliant insights, does his construction ultimately provide a salvation for science, or is it merely psychologized?

Yale religion professor Louis Dupre makes an excellent point on the difficult intellectual position post-enlightenment man is left in, writing:

This removal of transcendence fundamentally affected the conveyance of meaning. Whereas previously meaning had been established in the very act of creation by a wise God, it now fell upon the human mind to interpret a cosmos, the structure of which had ceased to be given as intelligible. Instead of being an integral part of the cosmos, the person became its source of meaning. Mental life separated from cosmic being: as meaning-giving “subject,” the mind became the spiritual substratum of all reality. Only what it objectively constituted would count as real. Thus reality split into two separate spheres: that of the mind, which contained all intellectual determinations, and that of all other being, which received them.7

Alhough this would seem to be only a commentary on the state of man, post-enlightenment, I believe there is also a powerful argument implicit therein, which hints at the solution to the chief epistemological problem of Hume and Kant.

Numerous problems arise when the individual’s mind is made the final reference point of predication. In other words, if the individual is cut off from the the totality of reality, including what he refers to as “transcendence,” meaning and predication cannot be coherent. If existence preceeds essence, to use the existential dictum, meaning loses all meaning, outside the individual subject. Kant believes that he can speak meaningfully about appearances, but not about the in-itself, the noumenal realm. I am in full agreement, then, with Hegel on this point of critique; the epistemological turn in enlightenment philosophers ends up only giving a semblance of knowledge.

Kant assumes, first of all, that all other minds naturally work in the way his Prolegomena and Critique of Pure Reason explain. I realize that Kant gives what he conceives to be necessary categories for the possibility of experience. At first glance, this seems beyond critique. My insight, however, is that Kant seems to be overstepping the bounds of the phenomenal/noumenal distinction at this very point. His position presupposes that all minds work according to the structure proposed by his system: nature simply constitutes the mind to so operate.

However, do we not have here a synthetic a priori statement that cannot be justified? For, to say “all minds work in this fashion,” is to make an a priori statement that expands upon the idea of minds and their actions. Has Kant not boldly stepped over into the noumenal realm when he speaks of “minds,” assuming other minds to work in this same fashion? Remember that Kant conceives of his pure intuitions and categories as necessary. My point is therefore proven by the fact that another’s mind can never be given to Kant in his experience of appearances. But according to Kant, the realm of absolute certainty is the realm of appearances (the phenomenal).

Another way to take this criticism is the path that Hegel takes. I said above that to cut the individual off from the totality of existence is to eliminate meaning. Such is precisely the criticism that Hegel gives of a Kantian-type approach. How can we make sense of a statement of fact if we cannot attain to the in-itself? How can conceptual meaning be correctly attributed to, and predicated of, an object of experience without relating it to the universal concept? But when one is dealing in universal concepts, one is stepping outside the realm of appearances only. Language itself seems to presuppose universals, as does mathematics. Hegel is absolutely correct that we must return to metaphysics and the in-itself if we are to make sense of our experience. In fact, the Kantian enterprise even presupposes this point when it attempts to speak about the noumenal at all. Even a purely negative statement, such as “the noumenal cannot be known,” is still a universal truth-statement about the noumenal. It at least assumes the noumenal exists.

I do not follow Hegel into a pantheistic, dialectical monism, however. I agree that we need the Absolute Mind to “stand behind,” if you will, the objects of experience, giving them underlying meaning. For experience to be meaningful, it must have essence precede existence, or else our experience loses itself in an endless sea of unconnected, meaningless events. The human self cannot be the unifying principle, since the self cannot attain to the omniscience necessary to say anything meaningful about a thing (to the universal, that is). It seems to me, then, that philosophy has come full circle from the ancients and scholastics. Hegel realized this, but I do not think his answer is coherent. The solution is likely to be found in a return to the approach of St. Anselm’s project of attempting to find a necessary proof for God.8 I do not say this merely because of personal preferences for religious philosophy, but because I think this move of Hegel to seek to return to metaphysics and his insight into the need to relate the particular to the whole to say anything meaningful about an object is the right approach.

It is here that I see something unique in the traditional conception of a revelation-based epistemology that hints at answering the dilemma that even Hegel leaves us with. In God there is an ultimate unity and an ultimate plurality, but rather than an impersonal thought of Aristotle or Hegel, the omniscient absolute is also personal. I believe this is key, because it seems that meaning presupposes personality, as opposed to impersonal, brute factuality that somehow gives rise to “meaning,” and I suspect this relates to the idea of the “logos.”
The problems presented by Hume and Kant (and Hegel) point us to the following needs: It seems we assume many philosophical issues relating to linguistics and meaning in order to predicate anything at all, and this prior meaning seems to need to emanate from beyond ourselves. We need to relate it beyond ourselves because the finite needs to relate the concept to the infinite to make its predication “stick” to the object, if you will.

We seem to need this ultimate universal to contain the universals in a personal, mental way, and not merely as an impersonal force. We also need to return to analogy in speaking of this Absolute in order to be able to know about this Absolute. Indeed, when I say “absolute,” in the realm of linguistic and interpersonal discourse, as you read this paper, it seems to assume a kind of analogical mode, whereby you seem to understand what I mean by “absolute,” and yet you and I are both finite.9 In doing this, however, we would be reversing the project of the nominalists and re-introducing, at least to some degree, the chain of being model, which is bound up with the notion of predicating things of God on the basis of a via negativa analogy. We must return to the external transcendent, but the transcendent must be accessible to the finite mind.


Works Cited

Dupre, Louis. Passage to Modernity: An Essay in the Hermeneutics of Nature
and Culture (Yale University Press: London, 1993).

Hume, David. An Enquiry Concerning Human Understanding in The Empiricists:
Locke, Berkeley, Hume (Anchor Books: New York, NY, 1974).

Kant, Immanuel. Prolegomena to Any Future Metaphysics (Hackett Publishing: Indianapolis, IN, 1977).

Runes, Dagobert. Dictionary of Philosophy (Littlefield, Adams & Co.: Ames,
Iowa, 1958).

4 thoughts on “Hume and Kant: The Synthetic A Priori Problem

  1. At the risk of exposing my own puerility as I am philosophically challenged; I suspect that everything existing is integral to infinity and further that infinity is made up of intelligent energy manifested in various interchangeable forms. Should this be the case, it would follow that the cause of everything in existence is thought. Some energy forms are individualized entities capable of self perception within the whole of space and a time construct as we tend think of it; having some ability to engage in creative thought – though this power is largely unrecognized. Human spiritual nature falls into this individualized category, though we seldom act like it -I suppose because we are typically addicted to gravitational limitation.

    At any rate I enjoy your thought process immensely. Thank you so much.
    Bruce K.

  2. good stuff. Do you have any good reference materiel that discusses the philosophical meaning and implications behind John, chapter 1? (the Logos passage about God).

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s