Hume and Kant on the Limits of Naturalism
Descartes came to rely on God for his understanding of reality. God became the guarantor of his work as a natural philosopher who tries his best to utilize his faculties to understand the world. However, Descartes comes to his reliance on God by engaging in a circular epistemological argument by which he needs to rely on clear and distinct ideas to prove God’s existence, and Descartes needs God’s existence to be able to prove that he can rely on clear and distinct ideas. Hume, out of his naturalistic empiricism, rejects any such arguments with reliance on God and is left with a field of conscious experience as the sole basis for understanding anything. The conscious mind remains a mystery for him. Let us again remind ourselves of what he says of the mind:
The mind is a kind of theatre, where several perceptions successively make their appearance; pass, re-pass, glide away, and mingle in an infinite variety of postures and situations. There is properly no simplicity in it at one time, nor identity in different, whatever natural propensity we may have to imagine that simplicity and identity. The comparison of the theatre must not mislead us. They are the successive perceptions only, that constitute the mind; nor have we the most distant notion of the place where these scenes are represented, or of the materials of which it is composed. (Hume 1978, p. 253)
Hume does what no other Western philosopher has done before him: he attempts to push thought up against its own limits, without religious or commonsense presuppositions. Hume is saying we cannot understand our minds in any ultimate sense, because we can neither view them in a perspicuous manner nor make immediate contact with anything apart from appearances. Even the very idea of reality would, for Hume, have to be but an idea to which we do not know what might correspond. For Hume, in his radical empiricist philosophical mode, mental life is enigmatic. Yet we—or, rather, the natural philosopher within us—wants to understand it all. So what do we do? We must ultimately rely on a kind of faith, albeit in a secular, naturalist form. Human reason cannot provide us with an ultimate understanding of reality, no matter how much it wants or purports to do so. This realization of the futility of human reason strikes Hume as a kind of revelation that will help him out of melancholic deliriums of reason. Only his secularized faith in nature can show him the light. Hume tells us how he comes back from playing backgammon with his friends only to find his cold natural philosopher’s writings:
Most fortunately it happens, that since reason is incapable of dispelling these clouds, nature herself suffices to that purpose, and cures me of this philosophical melancholy and delirium, either by relaxing this bent of mind, or by some avocation, and lively impression of my senses, which obliterate all these chimeras. I dine, I play a game of backgammon, I converse, and am merry with my friends; and when after three or four hours’ amusement, I would return to these speculations, they appear so cold, and strained, and ridiculous, that I cannot find in my heart to enter into them any farther. (Hume 1978, p. 269)
Hume is not opposed to science. Indeed he is all for it. However, if we are to rely on science, it cannot be because of reason; we have no rational reasons for relying on science. Hume must then rely on science because of something else—nature:
Nature is always too strong for principle. And though a Pyrrhonian may throw himself or others into a momentary amazement and confusion by his profound reasonings; the first and most trivial event in life will put to flight all his doubts and scruples, and leave him the same, in every point of action and speculation, with the philosophers of every other sect, or with those who never concerned themselves in any philosophical researches. When he awakes from his dream, he will be the first to join in the laugh against himself, and to confess, that ah his objections are mere amusement, and can have no other tendency than to show the whimsical condition of mankind, who must act and reason and believe; though they are not able, by their most diligent enquiry, to satisfy themselves concerning the foundation of these operations, or to remove the objections, which may be raised against them. (Hume and Beauchamp 1999, p. 207)
Hume finds his own philosophical speculations about ultimate reality as cold. The reason he finds them cold is easy to see. They are cold because they are—no matter how well thought out—done by a mind that is inherently lost, like a Pyrrhonian, and usually without knowing it. There is, however, a part of Hume that realizes that what reason has produced is cold, but also that he is more than reason; he is also one who lives in accordance with nature or lived experience. The reasoning part of himself that engages in speculative philosophy about the ultimate nature of reality is cold because it ends up in a place beyond nature and lived experience. It is, in a sense, tragically lost. There is no ultimate metaphysical ground for science and philosophy that reason can help us discover. Kant reaches a similar conclusion in a discussion of metaphysics. For Kant, metaphysics has been nothing but a series of mock combats:
So far, too, are the students of metaphysics from exhibiting any kind of unanimity in their contentions, that metaphysics has rather to be regarded as a battle-ground quite peculiarly suited for those who desire to exercise themselves in mock combats, and in which no participant has ever yet succeeded in gaining even so much as an inch of territory, not at least in such manner as to secure him in its permanent possession. This shows, beyond all questioning, that the procedure of metaphysics has hitherto been a merely random groping, and, what is worst of all, a groping among mere concepts. (Kant and Smith 1950, p. 21)
Kant’s approach to metaphysics is to delimit it from human understanding. For Kant, reason is what drives metaphysics in the Humean sense. Reason seeks answers to ultimate questions about reality that it cannot answer; in this sense it is, like Hume’s reason, incapable of solving the problems it sets out for itself within the domain of metaphysics. The only way to come to terms with reason is to accept that it will always continue to ask questions it cannot answer. From Kant’s perspective, this is not necessarily a bad thing, as reason can push us in the direction of attempting to understand more and more about reality.
Neither Kant nor Hume can be seen as committed to realist foundationalism in its ultimate sense. It is true that Kant attempts to build a foundation for science in his Critique of Pure Reason, but it is a foundationalism based on the elegant assumption that the postulation of a real world requires comprehensibility on our part. As we saw earlier, Einstein realized this:
One may say “the eternal mystery of the world is its comprehensibility.” It is one of the great realizations of Immanuel Kant that the postulation of a real external world would be senseless without this comprehensibility. In speaking here of “comprehensibility,” the expression is used in its most modest sense. It implies: the production of some sort of order among sense impressions, this order being produced by the creation of general concepts, relations between these concepts, and by definite relations of some kind between the concepts and sense experience. It is in this sense that the world of our sense experiences is comprehensible. (Einstein and Seelig 1960, p. 292)
Einstein credits Kant for having understood that the very idea of an external world requires that it is comprehensible. Einstein does not agree, however, with the way in which Kant sets up the comprehensibility:
The fact that it is comprehensible is a miracle. In my opinion, nothing can be said a priori concerning the manner in which the concepts are to be formed and connected, and how we are to coordinate them to sense experiences. In guiding us in the creation of such an order of sense experiences, success alone is the determining factor. All that is necessary is to fix a set of rules, since without such rules the acquisition of knowledge in the desired sense would be impossible. One may compare these rules with the rules of a game in which, while the rules themselves are arbitrary, it is their rigidity alone which makes the game possible. However, the fixation will never be final. It will have validity only for a special field of application (i.e., there are no final categories in the sense of Kant). (Einstein and Seelig 1960, p. 292)
For Einstein, human understanding of reality is not to be based on a system of fixed and indubitable cognitive structures, such as those Kant derives in the Critique of Pure Reason (the forms of intuition and the categories of understanding). Kant’s mistake was, according to Einstein, an underestimation of the role that science would come to play in informing us about the nature of reality. Kant thought he could delimit the fundamental nature of any empirical experience or scientific activity but, according to Einstein, his system of philosophy was incorrect. Indeed the whole project of attempting to establish any such fundamental system would fail, and it would be evident with the natural progression of science—a dynamically evolving, pragmatic activity that takes precedence over speculative philosophy in our claims of knowledge.