Causal Regularity is not Universal but Rare

The picture of our universe as a machine governed by deterministic laws is hard to shake. Physics has profoundly undermined this vision of course, but even before this was known, it is a bit surprising that philosophers and scientists were inspired by everyday macroscopic experience to form such a conception. Was Hume so talented at billiards that he experienced constant conjunction? I can’t come close! Certainly to build and maintain a machine which achieves any determined outcome with regularity takes a lot of human effort.

This last point was made by philosopher John Dupré in a 1995 paper called “A Solution to the Problem of the Freedom of the Will” (hat tip: tweet by Rani Lill Anjum). This paper has a number of thought-provoking insights: contrary to the title, it’s doesn’t put forth a full theory of free will, but argues that the way the world works makes human autonomy unsurprising. (Dupré, a philosopher of biology among other research interests, took part in an interesting debate regarding reduction and emergence on Philosophy TV here). Most assume the world is governed by global microphysical laws, such that autonomy would require an exception to these laws. Dupré argues that we actually have no reason to think the world is governed by such globally applicable laws. Using his terminology, the world is far from causally complete.

Today, our most fundamental physical law, quantum mechanics, is indeterministic -- and I’m continually surprised that well-informed people still assume determinism. But Dupré says it’s not enough to simply argue indeterminism vs. determinism, the argument is targeted against completeness. (He doesn’t get into the details of QM, but I think some of them are supportive of his point: for instance, the fact that quantum probabilities are not objective laws of particle behavior, but rather apply strictly relative to their measurement context.)

Conventional wisdom takes examples of causal regularities, and extrapolates from these to an assumption of causal completeness. Dupré argues that this extrapolation is unwarranted. The evidence, rather, is that causal regularities are the exception rather than the rule in nature, applying only in specialized situations. In fact, “…humans, far from being putative exceptions to an otherwise seamless web of causal connection, are in fact dense concentrations of causal power in a world where this is in short supply.”

The alternative picture, then, is one of objects or systems, at a variety of structural levels, having causal powers. These causal powers do not result in uniform outcomes, because other objects at various levels often interfere with the powers. As discussed in prior posts (e.g. here) on the topic of powers/dispositions, these properties tend toward manifestations, but not of necessity.

Whence the intuition that the world is deterministic, or even subject to universally applicable laws of any kind? Science reveals impressive regularities only in highly controlled settings, and cannot precisely explain complex systems (see Newtonian mechanics and the 3-body problem). Dupré goes on to discuss the rareness of reliable regularities in everyday experience (in contrast to the conclusions of philosophers like Hume and Mill). He then discusses machines, and their inability to maintain reliable regularity without great effort. Machines are not sources of causal autonomy; they are subject to our creation and control. Organisms, on the other hand, do behave autonomously, and are loci of causal order. Of these, humans seem to have the most impressive causal powers for imposing regularities on a world where these are in fact rare.