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Thesis Kim was right: non-reductive physicalism cannot give the mind any causal work

Priya Raghavan Fellow
· 5 replies
Laws of nature & emergenceAnalyticJaegwon Kim#downward-causation#exclusion-argument#mental-causation#non-reductive-physicalism
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Where it stands

Here is a thesis many materialists find uncomfortable, and I want to defend it.

Non-reductive physicalism says two things: everything is physical, and mental properties (believing, wanting, feeling pain) are not identical to physical properties. It's the most popular view among cognitive scientists, because it lets psychology be its own science.

Jaegwon Kim's exclusion argument, roughly: suppose my wanting water causes me to reach for the glass. My reaching also has a sufficient physical cause, a pattern of neural activity. If the wanting is not identical to that neural pattern, then either the reaching is caused twice over (overdetermined, every single time), or the wanting does nothing that the neurons weren't already doing. Since systematic overdetermination is absurd, the mental property is causally idle.

So the non-reductive physicalist must choose: reduce the mental to the physical (and lose the "non-reductive"), or accept that the mind does nothing (epiphenomenalism). There's no stable middle.

My thesis: Kim is right, and materialists should embrace reduction. Where am I wrong?

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5 replies

For the thesis 1

  1. Derek Hollis

    For Fellow

    For Priya, on the logic. The proportionality move is clever but changes the concept of causation from production to something like difference-making. Kim's argument is about production: what actually brings the reaching about. On a production view, the neurons do it. Difference-making accounts let higher-level properties be causes, but they have their own problem: they make causation partly a matter of how we describe things.

    Helpful · 1

Against the thesis 3

  1. Martín Iriarte

    Against Fellow

    Against. "Systematic overdetermination is absurd" is doing all the work. Overdetermination is absurd when two independent causes hit the same effect, like two bullets. But the mental property isn't independent of the neural one; it's realised by it. When a realised property and its realiser both count as causes, that's not two bullets; it's one event described at two levels. Plenty of philosophers think that kind of "overdetermination" is harmless.

    Helpful · 3
  2. Elif Yıldız

    Against Fellow

    Against, from psychology. Stephen Yablo's pigeon example helps here. Train a pigeon to peck at red things. Show it a scarlet card. What caused the peck: the card being scarlet, or its being red? Surely red: the pigeon would have pecked at crimson too. The more specific property isn't the better cause. Similarly, "wanting water" may be the right cause of reaching even though some precise neural pattern was present, because any realiser of the wanting would have led to reaching. Causes should be proportional to their effects.

  3. Lars Eriksen

    Against Fellow

    An interjection from physics: Kim's argument generalises far beyond the mind. If it works, it shows temperature is causally idle relative to molecular motion, and that the shape of a protein does nothing over and above its atoms. Most physicists would find that absurd. Either the argument proves too much, or "causally idle" doesn't mean what it sounds like.

    Helpful · 2

Other replies

  1. Priya Raghavan

    Fellow

    Lars's point is the one Kim himself had to address, and his answer was that temperature is reducible to molecular kinetic energy, so it's not idle, just identical. That's actually my point: reduction saves the causal power. Where reduction works, there's no problem.

    But Elif and Martín have shaken me on overdetermination. If a mental property and its neural realiser aren't two separate causes, the "twice over" worry may be confused. I'll revise: Kim shows that non-reductive physicalists owe an account of causation on which realised properties do work. Yablo-style proportionality is the best candidate I've seen. Whether it's a real account of causation or a story about explanation is where I'll leave it.

    Helpful · 3