[zcarter]

I find Terrence McKenna's argument that consciousness is demonstrably entangled in the material world at a quantum mechanical, atomic level convincing. To summarize, it is known that two similar chemical compounds, differing only in the placement of a single atom on the carbon ring structure of a molecule, when administered in doses at the order of micrograms will either be psychoactive and result in a massive disruption to the human subject's baseline consciousness or be inert beyond our ability to measure an effect.

[XorNot]

That provides precisely no evidence that consciousness is somehow related to events on the quantum level. We know why drugs have the effects they do - because the brain has receptors specifically calibrated to accept or reject molecular inputs. But those inputs are chemical, not quantum - they are not indeterminate, they are lynchpins in chains of chemical reactions.

You omit that if you give a much larger dose of the same thing you'd kill a person, and a smaller dose might fall below any threshold of activity at all.

And for that matter, a microgram is a huge quantity of matter.