Tag Archives: Time

Determinism and Free Will

In the Stanford Encyclopedia of Philosophy entry on Causal Determinism, Carl Hoefer suggests in the concluding section (Determinism and Human Action) that there is hope for those who want to believe in free will:

There is a long tradition of compatibilists arguing that freedom is fully compatible with physical determinism; a prominent recent defender is John Fischer (1994, 2012). Hume went so far as to argue that determinism is a necessary condition for freedom—or at least, he argued that some causality principle along the lines of “same cause, same effect” is required. …

Physics, particularly 20th century physics, does have one lesson to impart to the free will debate; a lesson about the relationship between time and determinism. Recall that … the fundamental theories … if they are deterministic at all, are time-symmetrically deterministic. That is, earlier states of the world can be seen as fixing all later states; but equally, later states can be seen as fixing all earlier states. …

Nor does 20th (21st) -century physics countenance the idea that there is anything ontologically special about the past, as opposed to the present and the future. In fact, it fails to use these categories in any respect, and teaches that in some senses they are probably illusory. So there is no support in physics for the idea that the past is “fixed” in some way that the present and future are not, or that it has some ontological power to constrain our actions that the present and future do not have. It is not hard to uncover the reasons why we naturally do tend to think of the past as special, and assume that both physical causation and physical explanation work only in the past present/future direction (see the entry on thermodynamic asymmetry in time). But these pragmatic matters have nothing to do with fundamental determinism. If we shake loose from the tendency to see the past as special, when it comes to the relationships of determination, it may prove possible to think of a deterministic world as one in which each part bears a determining—or partial-determining—relation to other parts, but in which no particular part (region of space-time, event or set of events, …) has a special, privileged determining role that undercuts the others. Hoefer (2002a) and Ismael (2016) use such considerations to argue in a novel way for the compatiblity of determinism with human free agency.


In a science brief, The Economist covers the mystery of time.

In 1887, Albert Michelson and Edward Morley found to their surprise that the speed of light traveling in different directions relative to the movement of the earth’s surface is constant. In 1905, Albert Einstein provided an explanation—his special theory of relativity—for the constancy of the speed of light. Time is “malleable, passing differently in different places, depending on how those places are moving with respect to one another. Indeed, at the speed of light, it stops altogether.” In 1915, Einstein argued in his general theory of relativity that space and time are connected and that they interact with mass.

As a consequence of the second law of thermodynamics (temperature differences tend to vanish, Ludwig Boltzmann, 1877) “any system will become more disordered as time passes. That applies as much to two gases mixing as it does to a teenager’s bedroom.” In 1927, Arthur Eddington drew the conclusion that time is unidirectional: There is a fundamental asymmetry between a system moving towards the future (increasing disorder) or the past (decreasing disorder).

Time travel is possible—in particular if one has easy access to “wormholes”—or so it appears. But the grandfather paradox lurks: Can one travel back in time and kill one’s ancestor in order to render one’s one birth impossible …?