Coel has put up a post on one of philosophy’s favourite topics: Brain in a vat (BIV). I’ll try to get to other sources, such as the Massimo Pigliucci post Coel refers to, but for now I’ll respond to Coel’s post only.
So, “[the BIV problem] supposes that we are a brain kept alive in a vat, being fed with a stream of inputs generated by an Evil Genius. Everything that we experience as sense data is not real, but is artificially simulated and fed to us.”
First, a quick comment on the Tatsuya Ishida cartoon. There should have been one brain in a vat, and both speech bubbles should have come from the same brain: one taking the part of the brain that is supposed to be the main character, and the other is the internal auditory perception of what the brain presumes to be the other character. Of course it could be that two brains in vats are being manipulated in conversation, but that then seems too much like an actual conversation between brains, and sort of misses the main point of BIV: all perceptions, whether thoughts of the lone BIV, or stimulated auditory perceptions that convince the BIV that it has heard another speak (and visually aware of the other, etc.). But that’s just nit picking.
Back to the problem. How can you tell if you are a BIV?
You can’t. Or rather I should say that so far we don’t know if you could tell or not. The significant point is that we can’t positively know we could tell the difference, between being a real brain in a human body, situated in the physical world we perceive, or being a BIV being stimulated to so perceive the world.
Coel’s parsimony point is right, but I disagree with his use of it. Parsimony is merely a pragmatic tool in an epistemically uncertain world. It assures us of nothing. The proper use of parsimony is that if there are two explanations (or theories) that fit the same evidence then we might as well use the simplest. Since both theories fit the evidence then by definition we can’t tell which is correct, and at that point it doesn’t actually matter.
Example: Theories X and Y fit evidence A, B, C. X is simpler than Y, so use X.
New evidence D also supports X and Y, so continue to use X.
Then, new evidence E comes along that supports Y, but not X. All of a sudden Y is looking interesting. E might be so convincing that it clearly falsifies X and supports Y. Then Y is the theory to use.
Later, evidence F, G might come along, some of which shows that the experiments that affirmed E were faulty, and F and G also support X and not Y. X is back on the front foot.
That’s how it works. In the case of the BIV problem we have zero evidence either way. We have no evidence supporting BIV, and not supporting the falsity of BIV. We cannot resolve it with any evidence we have.
So, what should we do?
Well, think about the consequences of perceiving the real world and being a BIV perceiving a stimulated fictional world.
What if we really are brains in vats? Or, following my criticism of the cartoon above, what if I really am a BIV, and you and everyone else I perceive are stimulated fictions? What can I do about it?
Bear in mind that I can’t even be sure I’m an actually brain in an actual vat either. I might be merely a computer simulation: of a BIV being stimulated to perceive a real world.
This scenario is so fucked up compared to my perception of a real world that there really isn’t much I can do about it. I might want to get all revolutionary on the Evil Genius’s ass; but really, if he’s controlling my brain (or simulating the control of a brain) then he’s controlling my revolutionary thoughts too. He’s actually making my brain wonder if it’s a BIV! The cruel bastard!
In the end I’m left with the correct use of parsimony. It seems like I’m perceiving a real physical world containing other real physical people, so why not simply use that as a working conclusion? Work in progress. Just like all the rest of science.
Note that this has nothing at all to do with thinking about a finite subset of infinite possibilities, or any of that crap.
“Any statement not supported by evidence is most likely to be wrong and thus should be discarded.”
No! This is not how it is. Any statement not supported by evidence is NOT most likely to be wrong! We simply can’t say if its true or false at all. We can’t say anything much about it at all, except that if we don’t have evidence to support it then it’s indistinguishable from a statement that is false, and as such is as useless as a statement that is false. Using terms like ‘most likely’ is totally inappropriate.
Take the statement, “Praying to Jesus gets results, sometimes.” Well, people pray often, and most times they get no result. Sometimes people pray and get the result they pray for. This is true for many sports competitions, since many people seem to pray to Jesus for victory in sports. But since someone wins and someone loses (barring the anathema of US sports – a draw) the actual result is indistinguishable from coincidence. Prayer, as a determiner of sports results might actually work. Maybe Jesus really does dish out results according to prayer and some other very complicated cosmic data he uses. But to us the use of prayer is indistinguishable from useless. [Note, that's not to say there are not other psychological consequences of prayer.]
“Regardless of whether the “world” is real or simulated, the standard scientific “real-world model” gives the greatest parsimony and predictive power in describing that world.”
Not so. The BIV, if that is the state of affairs, only ‘thinks’ the real-world model gives predictive power at all. The actual laws of the universe that the Evil Genius inhabits might be quite different from the one that the BIV thinks it inhabits, with very different laws. Of course the BIV can’t imagine what those laws might be, because the BIV is only aware of the ones it is programmed to perceive. All the ‘predictions’ the BIV thought it observed never happened. Have you ever noticed in a dream how natural and obvious some of that weird shit appears to be, how convincing it is, when in the dream? Well, why should that not be the case for the BIV? If you are a BIV then you haven’t ‘woken up’ yet to observe how false all your perceptions are; you are still in the ‘dream’ believing you can make predictions.
“Any departure from that standard model would result in a worse account (one that is less parsimonious and less predictive about that stream of experiences). That’s because science’s models do work very well about our world and are the best that we have.”
Not they don’t, if you are a BIV! They only appear to work very well.
“One might object that in a “brain in vat” scenario the Evil Genius could feed us any stream of experience he liked, with no rhyme or reason to it, no regularities and no predictability. That is indeed possible, but then the stream of experiences could only be described essentially as a streamed video tape, which is the most information-hungry type of model and one that would be totally useless at predicting anything.”
It doesn’t matter how information hungry the theory is from the perspective of the brain, real or BIV. This has nothing to do with it at all. The computer simulation of rolls of a dice are more information hungry than rolling an actual device since computer simulations are built on information hungry computers. But that doesn’t mean we should make a statement, “All simulations of dice in computers are actually real dice, since simulating a dice is more information-hungry, and by the rule of parsimony we should not believe that computers are ever simulating dice.”
“In contrast the “real world” model is very compact in that all one needs are the basic laws of physics and all else follows from that. This model has a vast amount of predictive power, as we know from the fact that engineering works, and planes we build fly, and predictions we make for solar eclipses come true.”
No! You, the BIV, only THINK planes fly, if indeed you are a BIV.
“The brain-in-vat model has no capacity to make any predictions at all about the stream of experiences, unless we make all sorts of assumptions about the Evil Genius and why he is feeding us the stream of experiences.”
Well, where in the BIV notion does it require us to be able to say anything at all about the Evil Genius? If I am a BIV then any assumptions I might presume to make are untestable bollocks.
But, the BIV model does make predictions. It predicts that the brain so programmed can make predictions. It can make predictions about its imaginary world, and it can make predictions about being a brain in a vat. They simply aren’t testable predictions.
“Yet, ex hypothesis, we can never have any information about the Evil Genius or his doings.”
Exactly. Including never having the information to know that you are not a BIV.
“The only way of regaining any degree of parsimony or predictive power…”
No, no, no! If you are a BIV you get only the predictive power that the system controlling you, or simulating you, gives you; which, if you are a BIV, is this very prediction that you are or could be a BIV. And it may all be fake. As a BIV you don’t get any say in anything! You don’t get to know anything. The very fact that you are wondering if you’re a BIV is a consequence of being that very BIV, but only because the stimulations or simulations produced by the Evil Genius allow it. That you are predicting the consequences of being a BIV is predicted by being a BIV, if you are a BIV.
Even if the Evil Genius attached some physical eyes onto the brain and allowed you to see him waving at you from outside the vat, you would have not way of knowing which of the following just occurred:
1) You are a BIV and just saw the actual Evil Genius.
2) You are a BIV hallucinating.
3) You are a real embodied brain in a real physical world hallucinating.
This is just like revelations from God that some religious people report, or when some ‘crazy’ person hears the voice of Jesus and neurologists see his auditory cortex buzzing away as if hearing real voices. Religious personal revelations might be real or they might be imagined. These are indistinguishable events. We reject them only because they don’t seem convincing to us most of the time, and because there is not convincing evidence. Though remember, to many religious people, belief is the parsimonious result.
And this is how we deal with the BIV.
Imagine I am a BIV. I am stimulated to perceive a physical world. That fake physical world model results in me learning some physics (maybe fake physics) and evolution (maybe fake evolution) and I conclude that I am evolved from animals that didn’t have brains and animals that had simple brains. With all that I conclude that I am a human animal. one of many, that has a brain that has quite a fertile imagination, and imagines it might be a brain in a vat.
Or, imagine I’m a real human in a physical world. That physical world results in me learning some physics and evolution and I conclude that I am evolved from animals that didn’t have brains and animals that had simple brains. With all that I conclude that I am a human animal. one of many, that has a brain that has quite a fertile imagination, and imagines it might be a brain in a vat.
These are truly indistinguishable. Otherwise we wouldn’t be having this debate. But note that one is a subset of the other. The simpler one, the latter, seems to work in just the same way as the former, except that the former has some features (me being a BIV) that I can’t actually observe or test. So, according to the principle (i.e. suggestion, recommendation) of parsimony I might as well go along with the latter.
Note that this is almost an arbitrary choice; but not quite. I could live my life as if I’m a BIV. Suppose I did so in one of two ways:
1) I live my life as if I’m a BIV, but I keep it to myself. I never tell anyone. I even try to fool myself that I don’t believe it. Other than a few personal psychotic moments how would this be different from believing I’m a real person in a real world?
2) I live my life as if I’m a BIV, but I try to tell everyone? But hold on, why would I? Since I’m a BIV what good would it do telling my imaginary fellow humans that don’t actually exist except as figments of my BIV? But suppose I did, and those very same figments of my BIV locked me up in an asylum. Well, it’s only an imaginary asylum.
The problem with the BIV perspective is not that it’s not real, but that it’s fucked up to think it is real. It just seems to add a layer of complexity that is unevidenced and unnecessary. I might as well go along with the apparent reality I perceive, whether it’s a real reality or a stimulated one or a simulated one.
Note that this is also how I see religion: an unevidenced and unnecessary level of complexity added to our experienced life; pretending we are God’s brains in his vat of a universe. So fucked up that it’s no wonder we get the craziness. But note also that it could all be true – all of it! Islam AND Christianity – all true but we poor brains in God’s vat simply don’t get the big picture; and William Lane Craig is right that all the dead children have been done a great favour. Religion is as exactly as fucked up as imagining we’re brains in vats. Once you start adding imaginary stuff on top of evidenced stuff, anything goes.
“The in-a-vat wrapper to the real-world model is along the same lines, a vast and needless complication that doesn’t in any way improve the model’s fit to evidence. We could just as well imagine any number of other parallel meta-realities that make no difference to what we experience.”
That’s right. That’s all it boils down to. A rather arbitrary choice, made because it makes life simpler, even if only apparently so.
“Since there are an infinite number of such possibilities the chances of any random one of them being actually true is infinitesimal.”
This is totally irrelevant. It wouldn’t matter if there were only two possibilities: 1) real world, as we actually perceive it; 2) BIV, stimulated to perceive the world as we actually perceive it.
“Thus, by the adoption of the usual scientific method, invoking Occam’s razor and principles of parsimony and the need for predictive power, we can reject brain-in-a-vat scenarios.”
No. Only the principle of parsimony is necessary. Predictive power is of no use, since a BIV makes the same predictions. We cannot reject the BIV with any conviction. Instead we simply choose to reject it because that’s easier. There is no other convincing reason.
“That, of course, does not mean that they can be absolutely ruled out, any more than we can rule out any other hypothesis designed to leave no discernible trace at all on our experience of the world (apophatic theologians are particularly good at inventing these), …”
“… but the chances of any such suggestion being true is too low to merit taking it seriously.”
No. It’s nothing to do with chance, probability, possibilities, or anything else. It’s simply taking the simpler option that doesn’t require that we sustain belief in things (Evil Genius, vat, disembodied stimulated brain) that we cannot test.
Coel refers to Descartes and his Cartesian Doubt, whereby Descartes digs deep into a reasoned sceptical investigation to figure out what lies at the bottom when all our uncertainties are stripped away. His working conclusion is cogito ergo sum, I think therefore I am. From there Descartes cocks it all up, because he already believes in God and he just can’t drum up enough doubt about that.
But his Cogito is about the only place I can see we can start from. Coming up from there I can’t see any difference between our perceived reality and solipsism, or a BIV. That’s the only starting position I have, and that’s were I take it from here: Contingency of Knowledge.