The general argument is that Kant was not a materialist but a transcendental idealist. However, that is not an argument but more like a conformation to Kant’s really twisted view. Prefix “trans-” means “on the other side.” What is on the other side of idealism? A transcendental idealist is a non-idealist. Kant was indeed a non-idealist, and he criticized idealists for their being removed from empirical reality. Moreover, he rejected realism and believed that mysticism was meaningless. That’s an eliminative way to figure that Kant was really a materialist. Another way is to look at what he advocated.
Kant advocated to not perceive reality as it is (that’s mere appearances to Kant) but to go beyond forms and find particles (“quantum” or “manifold”) on the other side. So, he first superseded perceptions and then conceived of individual sensations and thus laid the ground for atomist and particle physics (atoms were discovered after Kant). Kant had also greatly influenced the philosophy of pragmatism. Matter that only consists of particles is what Kant was calling the noumenal reality, and it was his ultimate goal to reach it by the means of his ideas. Thus, Kant fed his consciousness, as every materialist does, to primal matter. This way, possibly subconsciously, Kant was going against consciousness toward Nonexistence. The scary thing is that, because of Kantian influences, most philosophers did (and are still doing) that, including Rand.
Seemingly, most philosophers only look at the secondary side of Kant, while his primary side–materialism–stays in the shadows. I have read Kant’s Critique of Pure Reason (COPR-link), and I have to say that he fed his “transcendental ideas” to primal matter.
The following are my approximate definitions:
- Materialism is a scientific philosophy that feeds consciousness to matter. Materialists believe that only particles exist and everything else is an opinion. In addition, quantum physicists believe that Particles Are Energy, which is the metaphorical definition of annihilation.
- Mysticism is a spiritual philosophy that feeds consciousness to a greater consciousness. Mystics believe that we have emotional souls that help us connect with God and that our main purpose is to bring God to our physical reality.
Materialism and mysticism are incongruent. Master mystics like Jesus Christ have idealized and realized genuine emotional love. Kant (a master materialist, in my view), on the other hand, never even mentioned the word “love” in COPR, except once, in the form of “beloved,” when he talked about metaphysics (p. 473). Kant decides to “transcend” the meaningless (for him) belief in the soul and God and ends up in primal matter:
[I]t must not be supposed that any beginning can take place in reason; on the contrary, reason, as the unconditioned condition of all action of the will, admits of no time-conditions, although its effect does really begin in a series of phenomena—a beginning which is not, however, absolutely primal (COPR, p. 326).
An exact corollary of materialism is mereological nihilism, which is practiced by some schools of Buddhism. It claims that “‘wholes’ themselves only exist at the subatomic level.” For instance, take the following: “Nihilists typically claim that our senses give us the (false) impression that there are composite material objects” (wiki). And compare this to Kantian phenomenology:
I understand by the transcendental idealism of all appearances the doctrine that they are all to be regarded as mere representations and not as things in themselves, and accordingly that space and time are only sensible forms of our intuition… (COPR, A 369, cited in wiki).
So, Kant makes “transcendental” reason into a phenomenal property (also meaning “things” sensed) and things-in-themselves into irreducible parts like atoms, and he sets the second primary. Do you still doubt that Kant was really a materialist? I bring up this article in support rather than in contradiction to what I am claiming, as some of you may think. Read it carefully.
This and this article try to make Kant seem anti-materialist, but they are wrong. A disagreement on some idea is meaningless even in the Kantian sense; their overall materialist philosophy is the same. In other words, while the direction (toward matter) does not change, minor changes in position or scope do not affect the core of this philosophy.
For a more complete analysis of Kantianism and comparisons to Platonism and Aristotelianism, see my original post on Kant. For more on Rand’s view on Kant, read her article “Causality Versus Duty” (1974). Kantian materialist ethics of duty directly opposes virtue-based inclinations of idealists and (progressive) realists. Those who match the philosophical position of reality but still reduce reality to matter shall hereby be known as regressive (or reductionist) “realists.” An example of those is V.I. Lenin, whose literal interpretation of Society Is Nature metaphor was at the core of his philosophy that led to the establishment of the well-known technocratic society. To those Americans who like to deceive themselves by thinking that the chaotic trends of the 20th century are behind us should look closer to reality. For example, they could find that Alan Watts’s literalization of Organism Is Environment metaphor is still a vibe with some today.
 Some misintegrating, subjective idealist/materialists–of Cartesian variety–take this one step further and claim that “everything is energy,” calling matter by what it’s not. Their way of hiding materialism under idealism traps them until they realize that energy qua energy doesn’t have spin, charge, mass, wavelength, or impulse.
 The Urantia Book defines mysticism as “the technique of the cultivation of the consciousness of the presence of God” (p. 1097) and warns that if “such practices lead to social isolation and culminate in religious fanaticism, they are all but reprehensible” (ibid.).
 Although the contemporary cognitive linguist George Lakoff found the Platonist Essences are Ideas (conceptual) metaphor, he conveniently ignored the Kantian Essences Are Matter, maybe because he also shares its frame subconsciously. The conflict between these two frames can also be seen in today’s written communication landscape: the process methodologists view reality as process, and the (anti-foundationalist) post-process methodologists view language as a reality. Their views of reality are vastly different: the first is linear from private to public, and the second is triangulated and connected to situation ad hoc.
 In “What the ‘Friends of the People’ Are and How They Fight the Social-Democrats” (1894)
 In “The Book: On the Taboo Against Knowing Who You Are” (1989)