This is the weekly Q & A blog post by our Research Professor in Philosophy, Dr. William Lane Craig.
People talk about time having a direction, but we really cannot experience time without also observing objects within it. Perhaps the arrow of time is a property of the particles that "stuff" is made of and the direction seems universal because virtually all the particles around us have that same bias. (sort of like the fact that virtually all matter aound us is matter rather than antimatter) Is this a reasonable perspective?
Dr. William Lane Craig’s Response
Your question serves to draw our attention to perhaps the most important feature of contemporary philosophy of time, namely, its having been almost thoroughly “naturalized.” That is to say, philosophers of time work almost exclusively under the unspoken (and perhaps even unconscious) assumption of so-called “naturalized epistemology.” According to this perspective, philosophy is not an autonomous discipline but must be pursued within the framework of our best theories of physics. As a result, any investigation of the philosophical assumptions of modern physics is off-limits. Physics has a ring in the nose of philosophy and leads it wherever it wills.
There is (and can be) no justification for this naturalized epistemology, for that would require a perspective independent of modern science, which that epistemology prohibits. It can be adopted only as a personal methodological assumption by an individual philosopher. I flatly reject the assumption of naturalized epistemology. The question of the nature of time is a metaphysical question which cannot be answered by physics alone.
As a theist I have a knock-down argument that time is a reality which transcends physics. For we can conceive of God in the absence of any physical universe as having a succession of thoughts (or creating an angel with a succession of thoughts), say, counting “1, 2, 3,. . . .” Such a succession of mental events is sufficient for time, wholly independently of any physical reality.
So it is false when you say, “we really cannot experience time wthout also observing objects within it,” unless you include mental events under “objects.” So the arrow of time cannot be identified with any physical property (like the direction of increasing entropy) such as you suggest. Such reductionistic accounts also turn out to be viciously circular, since they presuppose that the direction in which, e.g., entropy increases is the later than direction.
So I think that any right-thinking philosopher should recognize a distinction between metaphysical time and physical time (or times, since there is no unified concept of time in physics). The former is time itself, while the latter is those various physical measures of time which we use more or less successfully to measure time itself. Time and its arrow are independent of our physical measures thereof.
If you’re really interested in pursuing this, take a look at my Time and the Metaphysics of Relativity (Dordrecht: Kluwer, 2001).