Quantum theories of mind and decoherence

Abstract

Two principle concerns prompt some theorists to link quantum mechanics and theories of mind or theories of consciousness. On the one hand, it is commonly thought that conscious minds play some important role in processes of quantum measurement and that any good theory of mind ought to explain how a mind can play such a role. On the other hand, a few people think that the framework of classical physics is not, by itself, sufficiently powerful to explain the myriad remarkable properties of minds and that a good explanation must rely on some special features of quantum mechanics. Usually, these features include either state vector reduction-the collapse of the wave function-or special capabilities, often computational or super-computational ones, allegedly displayed by physical substrates while existing in hypothesised coherent states of linear superposition. Two questions summarise the author's misgivings about both the above motivations for linking quantum mechanics and theories of mind. First, does the process of quantum measurement really require a conscious observer? Second, does quantum mechanics underwrite any special effects in, say, intraneuronal protein lattices, which could play a role in instantiating consciousness in biological systems? It turns out that the particular character of the negative answer suggested for the first question also prompts a negative answer for the second. He summarises these negative answers after describing briefly some popular attempts to forge quantum theories of mind.