Do all brains have neurons? Metaphysics and neutrality in <i>The Brain Abstracted</i>

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.