Does it feel any different to be reverse-chiral life? – Unstable Ontology

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I will examine the concept of chirality (the difference between a right hand and a left hand, generalized) and its relevance to philosophy of mind. Philosophy of mind often deals with colors: colors of worldly objects and of mental representations of them. Chirality, like color, can be experienced: it feels different to look at a left hand compared with looking at a right hand. Physics treats chirality more directly than it treats color.

Parity symmetry is a feature of some physical universes, but not our own. A parity symmetric universe (assuming it is, like ours, 3D in spatial coordinates) has the property that a universal parity inversion (which negates x, y, z coordinates of everything) makes no physically detectable difference. Parity symmetry is broken in our universe; this was shown in 1957. As a science fiction exercise, I imagine a universe much like ours, but with parity symmetry.

In another universe…

In this parity-symmetric universe, physicists fail to detect any parity violation, concluding that parity symmetry really does hold. They conclude that a possible cosmic state of affairs, and its parity inversion, are physically equal. There is no physical difference between them, only a change in coordinates. The universe needs no absolute chirality, any more than it needs absolute spatial coordinates: chirality is not an intrinsic physical feature of objects.

Philosophical attitudes differ. Physicalists believe the physicists’ parity-invariant ontology is correct: absolute chirality exists neither in objects, nor in mental perceptions. This ontology is counter-intuitive, because the experience of looking at a normal clock seems different from the experience of looking at a backwards clock.

Chiral materialists believe that physicists have left something out of their description of the universe. They believe that objects really do have absolute chiral properties: a forwards clock is intrinsically different from a backwards clock. Chiral materialists hold that, while chirality is not strictly speaking a physical property, it is a material property of objects, and not an intrinsically mental one. Chiral materialists are attracted to a Newtonian or 3D cellular-automaton picture of the universe, in which chirality really exists at the fundamental level, even if physicists cannot detect it.

Chiral materialists disagree about how human perception of chirality works. Direct realists say that humans directly perceive the material chirality of objects they look at, at least in the good case of veridical perception. Indirect realists say that humans create internal mental replicas of objects, and then directly perceive the (material) chirality of these replicas.

In cases of veridical chirality perception, there is not a good way to tell the difference: any internal replica of the object would have the same chirality as the object itself. But hallucination is, in principle, possible. A human could look at a normal clock, and by physical miracle, receive a retinal image as if looking at a left/right flip of that clock. Indirect realists reason that the human’s internal replica of the clock now has reversed chirality, and the human perceives this replica, which is why they see the clock as backwards. Direct realists say this is a case of false perceptual belief, and should not be taken too seriously as ontology.

Direct and indirect realist chiral materialists agree that, if there is a planet out there that is an exact chiral inverse of Earth, then reverse-chiral humans are having chirality-reversed experiences. Both the material objects they look at, and any internal replicas (if those exist), have reverse chirality. The reverse-chiral humans’ veridical perception of what they would consider a normal clock is, according to humans, a backwards clock.

Chiral dualists point out an “epistemic gap” for chiral materialism. Even granting that material objects (and any internal replicas of them) have intrinsic chiral features, why must phenomenal experiences of them take on the chirality of the objects or the replicas of them in the brain? Chiral dualists argue that a “phenomenal chiral invert” is conceivable: someone could be physically (and material-chirally) identical with a normal human, yet have a consistent left/right mirroring in their entire experience (visual, auditory, tactile, and so on). Their visual experience of seeing a normal clock is like a typical person’s visual experience of seeing a left/right inverted clock; they’re just used to it, so they act normal about it.

Chiral materialism gives no easy way of ruling out this scenario; it’s really a guess that experiences track the material chirality of external or internal objects. Chiral dualists infer, from the conceivability of chiral inverts, that there must be a non-material feature which fixes chirality. Perhaps humans have souls, which contain...