Nevertheless, despite its universality, its quest for certainty, its reliance on reason purified from all distortions of sensation and prejudice by the use of mathematical method, and the reproducibility of its findings, science does not – and cannot – provide us with absolute knowledge. The reasons are not only methodological but also substantive, and not merely substantive but also intrinsic and permanent.
The substantive limits of science follow from certain fundamental aspects of scientific knowledge and from science’s assumptions about what sorts of things are scientifically knowable. they stem from science’s own self-proclaimed conceptual limitations – limitations to which neither religious nor philosophical thought is subject. This is not because, since being rational, it is incapable of dealing with the passionate or subrational or spiritual or supernatural aspects of being. It is, on the contrary, because the rationality of science is but a partial and highly specialized rationality, concocted for the purpose of gaining only that kind of knowledge for which it was devised, and applied only to those aspects of the world that can be captured by such rationalized notions. The peculiar reason of science is not the natural reason of everyday life captured in ordinary speech, and it is also not the reason of philosophy or of religious thought, both of which are tied to the world as we experience it, even as they seek to take us beyond it.
Consider the following features of science and their contrast with the realm of ordinary experience. First, science at its peak seeks laws of nature, ideally expressed mathematically in the form of equations that describe precisely the relationships among changing measurable variables; science does not seek to know beings or their natures, but rather the regularities of the changes that they undergo. Second, science – especially in biology – seeks to know how things work and the mechanisms of action in their workings; it does not seek to know what things are, or why. Third, science can give the histories of things but not their directions, aspirations, or purposes; by self-definition, science is non-teleological, oblivious to the natural purposiveness of all living things. Fourth, science is wonderful at quantifying selected external relations of one object to another, or an earlier phase to a later one; but it can say nothing at all about inner states of being, either of human beings or of any living creature. Fifth, and strangest of all, modern science does not care much about causation; it can often predict what will happen if certain perturbations occur because it knows the regularities of change, but it eschews explanations in terms of causes, especially ultimate causes.
In short, we have a remarkable science of nature that has made enormous progress precisely by its metaphysical neutrality and its indifference to questions of being, cause, purpose, inwardness, hierarchy, and the goodness or badness of things, scientific knowledge included.
Let me illustrate these abstract generalizations with a few concrete examples. In cosmology, we have seen wonderful progress in characterizing the temporal beginnings of the universe as a “big bang” and elaborate calculations to describe what happened next. But from science we get complete silence regarding the status quo ante and the ultimate cause. Unlike a normally curious child, a cosmologist does not ask, “What was before the big bang?” or “Why is there something rather than nothing?” because the answer must be an exasperated “God only knows!”
In genetics, we have the complete DNA sequence of several organisms, including man, and we are rapidly learning what many of these genes “do.” But this analytic approach cannot tell us how the life of a cockroach differs from that of a chimpanzee, or even what accounts for the special unity and active wholeness of cockroaches or chimpanzees, or the purposive effort each living thing makes to preserve its own specific integrity.
Leon R. Kass – Leading a Worthy Life: Finding Meaning in Modern Times p.299