As I understand it, substance dualism is a position that holds that current physics and neuroscience cannot account for certain properties of qualia and the mind, implying the existence of some other kind of substance unlike matter or energy, carrying out processes and interacting with human brains. It was developed in large part by René Descartes and is closely related to his proposition cogito ergo sum.
An argument in favor of it is the
knowledge argument, which emphasizes that no matter how long a color-blind scientist studies the properties of light, the human eye, and the neurological processes behind sight, they will not gain knowledge of the qualia that a different person experiences when they see colors. Some other arguments are based on the ideas of the philosophical zombie, solipsism, and the nature of perception.
In my personal experience, common arguments against and blunt dismissals of substance dualism seem to commit one or more of three fallacies:
- A basic misunderstanding of the position itself.
- Erroneously lumping whoever holds the position with some other, perhaps 'discredited', position (religion and spirituality, anti-science, pseudo-science, solipsism, etc.) or a straw man.
- Misapplying the burden of proof.
With regards to this third type of argument, I'd like you to think about dark matter and dark energy. Physicists readily believe these phenomena exist and indeed compose most of the known universe, and yet the fields of physics and cosmology cannot yet account for them. No existing theory predicts them. Similarly, substance dualism is not necessarily put forth as a complete theory but rather as an observation of phenomena that science has yet to explain. And yet, it seems that substance dualists are expected to explain how their position might conform to current understanding of physics and the brain.
I'd be interested to hear any arguments against (or for) substance dualism which avoid these pitfalls.