Why causality (and free will) are dead

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Something caused you to click on this post. Or, at least, it’s likely you can identify a clear, well-defined origin to your current state of reading these words. Perhaps you were compelled from the title. Maybe it appeared in your inbox and you decided to give the first paragraph a go. Failing all of that, perhaps you slipped on a perfectly positioned banana skin, executing a flawless mouse click that only the most comedically-inclined cartoon could contend with.

Whilst equations in physics don’t explicitly reference causality, there’s a good case to be made for some type of causal relationship between events. Einstein’s relativity forces a more nuanced take on this, but there is still a persistent intuition that (speed of light permitting) objects influence each other through cause and effect.

Whilst I think a macroscopic definition of causality is helpful, even necessary, for a lot of uses, the mathematical elephant in the room cannot be so easily dismissed. In addition to the absence of causality, equations also eschew any reference to the arrow of time. The two are, of course, infrangibly linked.

Furthermore, there is a special case of causality resulting from conscious agents, better known as free will. To impose causal realism on our universe, we should either construct a satisfactory mechanism for volitional actions or be forced to dismiss it. Whilst intuitively it is hard to give up the idea of free will, the latter is much more easily unified with our understanding of reality. I accept that, in isolation, removing free will is not a sufficient condition for getting rid of causality, but I do think its uprooting naturally fits into the model of causal scepticism that arises when we reduce the universe down to its essentials.

It’s easy to dislike reductionism for its lack of imagination, and a move towards treating emergent phenomena as entirely distinct is becoming more mainstream. Nevertheless, if reductionism contradicts an emergent property, then we should give it precedence. For example, we can set out how thermodynamics works at a microscopic level and a macroscopic one but claiming pressure is anything but the increased collision of particles with the surface of a container would simply be incorrect.