How can one readily determine that the reality one experiences is real, not virtual - perhaps through Turing machine logic?
I haven't read through all this yet, but it looks interesting. The situation Putnam has created seems to be applicable to religious versions of reality in which there is a god that creates everything, and thus we are no more 'real' than what that alleged god has imagined. I'll have to do some more reading on this topic later if you're interested in discussing.In a famous discussion, Hilary Putnam has us consider a special version of the brain-in-a-vat hypothesis. Imagine that you are a brain in a vat in a world in which the only objects are brains, a vat, and a laboratory containing supercomputers that stimulate the envatted brains. Imagine further that this situation has arisen completely randomly, and that the brains have always been envatted. No evil neuroscientists or renegade machines have brought about the brains' envatment. Call such a special brain in a vat a ‘BIV’. A skeptical argument just like that above can be formulated using the BIV hypothesis. Putting things now in the first person, Putnam argues that I can establish that I am not a BIV by appeal to semantic considerations alone — considerations concerning reference and truth. This will block the BIV version of the skeptical argument.
Gelsamel Epsilon said:If we are indeed in a vitual system then we'd be living under vitual rules and any logic of ours would be restricted under those rules and hence could not predict or speculate about 'outside' the system.
Not sure what you mean here. I think the term "brain" is preferred over "mind" when referring to a "brain in vat" (ie: as opposed to a "mind in vat") because we think of a brain as being a material thing which can be physically inside another material thing (vat) whereas a mind is not. A mind is had by the brain, or is supervenient on the physical 'brain' so the phrase "mind in a vat" doesn't make as much sense. It's not the vat that has a mind, it is the brain that has a mind.How would BIV differ from "mind in a vat"? Does not the duality between scientist and brain, or god and mind assume a tangible horizon?
In other words, if your reference to the tree is not based on actually seeing a tree, you can't have the same meaning as someone who has seen the tree. That's basically Putnam's argument against BIV's having the same experience as a brain that actually exists outside a vat.Call these considerations about reference and truth semantic externalism. This view denies a crucial Cartesian assumption about mind and language, viz., that the BIV's sentences express systematically mistaken beliefs about his world, the very same beliefs had by a normal counterpart to the BIV, with matching experiences. On the contrary: the BIV's sentences differ in reference and truth conditions (and, accordingly, in meaning) from those of his normal counterpart. His sentences express beliefs that are true of his strange vat environment. The differences in the semantic features of the sentences used by the BIV and those used by his normal counterpart are induced by the differences in the beings' external, causal environments.