Did someone need an evil dream demon? Descartes?
Amazing coincidence has found me simultaneously working on a paper/presentation on Descartes’ Second Meditation–the infamous treatise that suggests the solution to hyperbolic-doubt-blues is the indubitable, positive affirmation “cogito ergo sum” (I think therefore I am)–and Hilary Putnam’s classic analytic philosophy essay Brains in a Vat–which is usually taken to be the hip-hop remix of Descartes’ argument.
In Descartes’ hit single the knowledge gained through sensory inputs is problematic in that it might be the result of an experience in a dream–as opposed to an experience of a world outside the observer–or the result of an evil demon with nothing better to do than implant false sensory data. Since, even under the influence of Freddie Kruger–an evil dream demon–we can always be certain that we are thinking–even if what we are thinking about is false–Descartes argues that we can be certain we are thinking things. In the brain in a vat version, Robert England’s role is taking by some amazingly complex computer (HAL 9000) that can present brains soaking in nutrient solution with false experiences normally reserved for folks with limbs and such. These experiences are so perfect that they cannot be discounted as dreams–as they have just the sort of continuity and causality one would expect from waking experience and the brains have no other experience of the world to compare them to–so it is argued that one cannot know whether it is the spoon that bends or you who bend. Syllogistically, the Brain in a Vat argument goes something like this–where P is anything I could know:
1. If I know P, then I know that I am not a brain in a vat
2. I do not know that I am not a brain in a vat
3. Thus, I do not know that P.
Hilary Putnam’s argument suggests that the resemblance between the experience of a brain in a vat and the experience of an actual meat-puppet is merely accidental. What is necessary to understand is that a brain in a vat’s experiences do not actually refer to anything–as they can’t because neither the brain nor the computer actually knows what a tree is when it feeds the experience of seeing a tree to a person and the person seems to experience it. This lack of necessary connection between visual image or mental speech means that even if a person called themselves a “brain in a vat”–they still wouldn’t have the necessary reference for what a “vat” and “brain” to actually be accomplishing any cognitive work. That is to say, the terms “vat” and “brain” refer to an object only if there is an appropriate causal connection between that terms and the vat and brain objects in the real world. Through some more analytic sleight of hand Putnam finally argues that since–even if one did accidentally identify its plight correctly–the “I am a brain in a vat” statement uttered by a brain in a vat wouldn’t actually have the necessary referential quality to be true and so–is false.
1. Assuming we are brains in a vat
2. If we are brains in a vat, then the term “brain” does not refer to (real) brain, and the term “vat” does not refer to (real) vat
3. If the sentence “brain in a vat” does not refer to (real) brains in a vat, then the sentence “we are brains in a vat” is false
4. Thus, if we are brains in a vat, then the sentence “We are brains in a vat” is false.
Having addressed Descartes’ demon in HAL 9000 garb, Putnam puts on a little celebration in honor of the occasion and writes this most striking passage near the end:
There is a ‘physically possible world’ in which we are brains in a vat — what does this mean except that there is a description of such a state of affairs which is compatible with the laws of physics? Just as there is a tendency in our culture (and has been since the seventeenth century) to take physics as our metaphysics, that is, to view the exact sciences as the long-sought description of the ‘true and ultimate furniture of the universe’ (…) Truth is physical truth; possibility physical possibility; and necessity physical necessity, on such a view. But we have just seen, if only in the case of a very contrived example so far, that this view is wrong. The existence of a ‘physically possible world’ in which we are brains in a vat (and always were and will be) does not mean that we might really, actually, possibly be brains in a vat. What rules out this possibility is not physics but philosophy.
The dominant-since-the-seventeenth-century tendency Putnam refers to is none other than the Copernican Revolution–that paradigm that argues that naive experience must be disregarded in favor of scientific process and the narratives of folk wisdom must give way to the–often counter-intuitive–theories of science. Putnam’s claim to have done nothing less than demonstrate that philosophy ought to redecorate the “true and ultimate furniture of the universe” was first published in his monograph Reason, Truth and History in 1981–no less than thirty years ago. One would think that in thirty years someone would have noticed.
(NOTE: For the hardcore philosophers: 1) why are you reading my blog?–and 2) yes, I know how contested the causal constraint of reference is and Brueckners’ argument that the most the argument proves is that a) if we really are brains in a vat, then the sentence “We are brains in a vat” (as uttered by a BIV) is false, and b) that if we are not brains in a vat, then “We are brains in a vat” is false (now expressing a different false proposition). My post is really a somewhat tongue-in-cheek dig at natural science based conceptions of reality in general rather than a rant that the world needs to get some philosopher-kings up in here. )