Getting back to my demonstration of why philosophical materialism undermines human reason, I want to discuss briefly Immanuel Kant. Recall that the dilemma posed to human knowledge by materialism was keenly felt by Hume, a problem that has become especially acute in our own day now that many scientists and philosophers have come to argue that human consciousness is reducible to physical brain processes.
If consciousness is just brain activity, how could it reveal to us a world that is external and other? Our neural activity exists entirely in the spatial confines of our own brains. Given that this is so, the best that our brains could do for us is to give to us representations of the world external to us, but they cannot give us the world as it is in itself.
Hume saw that reductionism of the sort that is prevalent in contemporary brain science should lead us to deny the objective reality of all so-called secondary qualities, which is to say of our entire perceptual experience. Our perceptions of color, sound, taste, etc. could only be innate ideas or internal representations that tell us nothing about reality in itself, if we presume philosophical materialism. In itself, reality would be a flux of material processes wholly other from our experience. Hume saw that the materialist account of perception also requires us to doubt the objective reality of our ideas of uniform causal influence and therefore of universal logical, mathematical, and scientific laws. If constant material flux or process is the only objective reality, then there is no “place” in the world to situate universal, uniform, unchanging laws of reason — except in the human mind. Our ideas of universal natural laws, then, can tell us nothing about the world in itself but only about our own psychology and ultimately about our own neural structure (Noam Chomsky has in fact reached this conclusion, albeit inconsistently, with his postulation of a “universal grammar” of the brain). All that we directly experience is the constant, contingent flux of matter striking our sense organs, and this can come to us only in point-instants of material process from which it is impossible to deduce universal causal influence in nature. Any universal laws of logic, math, or science, then, would have to be abstract or purely mental realities.
Hume, in drawing these consequences, was simply bringing a tradition of thought stemming from Descartes and Galileo, and consolidated on seemingly unimpeachable grounds by Isaac Newton, to its inevitable conclusion. In doing so, he unexpectedly shattered the logical foundations of modern science. No one understood the earth-shaking consequences of Hume’s conclusions better than Immanuel Kant, who sought to refute Hume and put science on a surer foundation of reason. But, in the end, all that he ended up doing was to give birth to a fantastic idealism that has given philosophy a bad name in the modern world. At least this is so in England and America, which have never been able to embrace fully the post-Kantian idealist strand of continental philosophy. Though, one could argue that this is largely to the discredit of Anglo-American philosophy, whose proponents are mostly shallow and ignorant of history.
Kant started his career as a science teacher and a physicist. He wrote a treatise in 1755 entitled The Universal History of Nature that anticipated many of the scientific cosmological theories that would be explored in astronomy in the next two hundred years. Kant was thoroughly Newtonian in these early stages of his career, but his reading of Hume in the 1760s called the whole Newtonian project into question for him. The question that Hume raised, that Kant realized was unavoidable, was how Newton’s purely empirical, contingent, and natural science could correspond to the necessary and universal dicta of formal and mathematical demonstration. Mathematical explanation was the ultimate goal of modern science for Newton and Kant (as it is for science today). But how could such universal descriptions fit the radically contingent structure of physical nature as it presents itself to our fleeting experiences?
Kant (and Newton) sought for universal and necessary axioms of nature, a goal that presupposes the conviction that nature is governed by uniform systems of cause and effect. As noted above, Hume called this conviction into question, and rightfully so, given the “sensationism” to which he was committed by virture of his materialism. The presupposition of uniform causal influence has no basis in reason because we have no access to it by experience. If matter is the only reality, there is no way that we could truly be said to know of the existence universal laws of causality. In fact, such laws could not even exist, though Hume himself did not reach this latter conclusion.
Kant, understanding the fundamental truth in Hume’s objection, tried to refute Hume and to establish the reasonableness of the Newtonian project by laying out a highly complex “transcendental” argument that presumed to show the basis in the human subject of all knowledge and experience. Jonathan Robinson, in his wonderful little book detailing the effects of bad philosophy on modern liturgy, summarizes Kant’s argument in support of the universality of science.
Beginning with the fact that physics is possible, because after all we in fact do it, he [Kant] then asks what the necessary conditions for the possibility of physics are. He then argues that among these conditions is the truth of the proposition that every event has a cause; and, if every event has a cause, then this establishes the reign of law in nature. The reality of this reign of law is what makes it possible for us to do physics. His position is that natural necessity constitutes the objective world we all experience, but we have no way of knowing whether or not this necessity also characterizes the world lying behind the objective world of experience. (The Mass and Modernity, 81)
Kant “rescues” or “saves” the reality of science, then, not on the basis of a correspondence between human experience and physical nature as it is in itself but on the basis of our own inner or “transcendental” experience. He remains committed to the materialist axiom that physical nature comprises nothing more than contingent material flux, whose importance for the problem of knowledge was made clear to him by Hume. But he refutes Hume by arguing that there is universality to our experience, as a result of the universality of human nature, and therefore that there is universality to science. In other words, the universal structure of physical laws is not found in nature but in the organizing capacity of the human person or subject.
Kant worked out a list of formal structures of the human subject that he held to be responsible for the ordering of our experience of contingent physical nature and which thereby make universal scientific deductions possible. These are known as Kant’s a priori categories of understanding. He establishes twelve such categories under four headings (quantity, quality, relation, and modality), each with three categories of its own. Kant also absorbed universal space and time entirely into the human subject. As for space, Kant says:
Space is not an empirical concept which has been derived from outer experiences. For in order that certain sensations be referred to something outside me (that is, to something in another region of space from that in which I find myself), and similarly in order that I may be able to represent them as outside and alongside one another, and accordingly as not only different but as in different places, the representation of space must be presupposed. The representation of space cannot, therefore, be empirically obtained from the relations of outer appearance. On the contrary, this outer experience is itself possible at all only through this representation. (Critique of Pure Reason, New York, 1958, 43)
As for time, Kant has this to say:
What we have meant to say is that all our intuition is nothing but the representation of appearance; that the things which we intuit are not in themselves as they appear to us, and that if the subject, or even only the subjective constitution of the senses in general, be removed, the whole constitution and all the relations of objects in space and time, nay space and time themselves, would vanish. As appearances, they cannot exist in themselves but only in us. What objects may be in themselves, and apart from this receptivity of our sensibility, remains completely unknown to us. We know nothing but our mode of perceiving them. (Critique of Pure Reason, New York, 1958, 46)
Space and time, Kant argues, are intuitions or forms of our innate sensibility, but not realities of the objective world itself. They must be presupposed in our experience and not derived from empirical encounter with physical nature. It can be no other way, once again, if we presume that the process, contingency, and flux of matter is the only reality of physical nature. We have to impose our mental life on physical nature in order to establish physical science, not understand nature in itself. If we want to save science, Kant realized, and yet maintain our commitment to philosophical materialism, we have to place the uniformity or universality of science entirely within our own mental life.
Indeed, Kant, through the influence especially of Ernst Mach, had an impact on Albert Einstein’s revolution of modern physics in his formulation of the relativity of time and space, though Einstein, who was not a competent philosopher, did not take things in the purely subjective direction that Kant did.
Can the universality of science really be rescued on a purely subjective basis? Postmodern thought has called the Kantian “rescue operation” into question by stressing the radically historical and contingent constitution of human nature itself. Nowadays, there are many who argue that science is an artifact of a particular historical mentality and not an expression of universal human nature. Indeed, human nature does not, for these postmodernists, even exist. So, the findings of science are not universally true for them in either an objective or a subjective sense. The postmodern turn will be the topic of my next post.
What is missing in the Humean/Kantian analysis? In the end, Kant does not succeed in saving science from Hume. If we truly want to affirm that science tells us about the universal laws of nature and not about our own psychology or history, we have to affirm (as Hume and Kant did not) the reality of formal causality in physical nature. In other words, we must affirm the presence of spirit in physical nature in order to account for the objective correlation of physical nature and human reason. But that will be the subject of my final post in this series.