From biology to physics and the unknown: What would it mean to understand consciousness?

None of the three classical theories of the mind–brain relation—Cartesian dualism, epiphenomenalism, and brain–mind identity theory—are based on explicit biological or physical mechanisms and are therefore not scientific. The Penrose–Hameroff orchestrated objective reduction theory does make testable biological predictions, but recent experimental tests require cautious interpretation. The neural correlates of consciousness do not support or falsify any of the three main ideas. To make the mind–brain problem scientific, conscious states must be measured directly, like electric current or blood pressure, with such measurements termed 'conscions' causally linked to neural activity. Even then, a deep gap remains, illustrated by Tyndall's point: knowing a molecule's handedness associated with love or hate does not explain why those feelings occur.

Study at a glance

Abstract

The three main ideas of the relation between the brain and the mind, Cartesian dualism, epiphenomenalism and brain–mind identity theory are critically reviewed. The point is made that none of these ideas, or their numerous variants, are based on explicit biological, or physical, mechanisms and are therefore not scientific in nature. By contrast, the Penrose–Hameroff orchestrated objective reduction theory does make testable biological predictions. I do not discuss the theory per se, but review two of its recent experimental tests for the purpose of urging caution in the interpretation of their results. A brief review of the neural correlates of consciousness follows. It is concluded that such experiments neither support nor falsify any of the three main ideas on the relation between brain and mind. First and foremost, science is experimental. Consequently, to bring the mind–brain problem in the realm of science requires that we directly measure conscious states the way that we measure electric current, or blood pressure, as examples. The entity of conscious state measurements will be referred to as ‘conscions’, and these must be causally linked to neural activity. If this were ever realized, a deep gap of understanding would persist. This is because of what I will refer to as Tyndall’s point. It can be summarized with a simple example as follows: if love were found to be associated with a right-handed turn of a given molecule and hate associated with its left-handed turn, then the question ‘why we have these feelings’ would remain unanswerable.