John Donaldson

Mazviita Chirimuuta’s The Brain Abstracted (2024) is a fascinating intervention into the philosophy of mind and neuroscience, containing deeply interesting ideas and arguments. Our aim is to critically probe whether Haptic Realism is neutral on some substantive issues which Chirimuuta would like it to be neutral on. Firstly, it is unclear whether Haptic Realism is compatible with Chirimuuta’s metaphysical neutrality. Causal notions feature heavily in Haptic Realism, including construction and interaction, without which it is unclear what the haptic component of Haptic Realism amounts to. We argue that the interpretation of these causal notions forces a choice that jeopardises metaphysical neutrality, since it is doubtful that there are any relevantly neutral theories of causation. Secondly, we ask the question ‘Do all brains have neurons?’ Haptic Realism trades on the idea of ideal patterns, patterns that are coaxed into existence by the interaction between practitioners and the world. If ideal patterns only exist within the confines of the lab, and neurons are idealizations, then brains out in the wild do not have neurons. Worryingly, this commitment of Haptic Realism undermines our ability to project neurological knowledge that we gain from studying particular brains to what is happening inside the everyday human beings.

I examine the debate between reductive and non-reductive physicalists, and conclude that if we are to be physicalists, then we should be reductive physicalists. I assess how both reductionists and non-reductionists try to solve the mind-body problem and the problem of mental causation. I focus on the problem of mental causation as it is supposed to be faced by non-reductionism: the so-called overdetermination problem. I argue that the traditional articulation of that problem is significantly flawed, and I show how to articulate it properly: what I call the ‘super-overdetermination problem’. In doing so, I demonstrate that the problem of mental causation faced by non-reductionism is in fact a special case of the mind-body problem, as faced by non-reductionism, and that the former can’t be solved independently of the latter. I then assess the prospects for a particular family of non-reductive views that I call immanentism, and show that they fail to solve the super-overdetermination problem. Finally, I put forward two arguments to support the conclusion that physicalism entails reductionism. Both arguments establish, via distinct reasoning, the proposition that mental property instances are identical to physical property instances; and then each argument employs the inference, which I also defend, that if mental instances are physical instances, then mental properties are physical properties; hence, reductionism follows.