Such knowledge of goals and such standards for judging better and worse are not easily had, and they certainly cannot be provided by science itself. In the scientific view of the world, there can be no knowledge, properly speaking, about the purpose or meaning of human life, about human flourishing, or even about ethics: opinions about good and bad, justice and injustice, virtue and vice have no cognitive status and are not subject to rational inquiry. These, as we are fond of saying, are values, merely subjective. As scientists, we can, of course, determine more or less accurately what it is different people believe to be good, but as scientists we are impotent to judge between them. Even political science, once the inquiry into how men ought to live communally, now studies only how they do live and the circumstances that move them to change their ways. Man’s political and moral life is studied not the way it is lived, but abstractly and amorally, like a mere physical phenomenon.
The sciences are not only methodologically indifferent to questions of better and worse. Not surprisingly they find their own indifference substantively reflected in the nature of things. Nature, as seen by our physicists, proceeds without purpose or direction, utterly silent on matters of better or worse, and without a hint of guidance regarding how we are to live. According to our biological science, nature is indifferent even as between health and disease; since both healthy and diseased processes obey equally and necessarily the same laws of physics and chemistry, biologists conclude that disease is just as natural as health. And concerning human longing, we are taught that everything humanly lovable is perishable, while all things truly eternal – like matter-energy or space – are utterly unlovable. The teachings of science, however gratifying as discoveries to the mind, throw icy waters on the human spirit.
Leon R. Kass – Life, Liberty, and the Defense of Dignity: The Challenge for Bioethics p. 44