HOW, IF AT ALL, CAN YOU KNOW THAT YOU ARE NOT A BRAIN IN A VAT
[How can we know we are not a Brain in a Vat]
The primary goal of the philosophical skepticism is offering arguments that conclude in the fact that we do not have as much knowledge of the world as we believe. Hence, to understand and address those concerns regarding the things we cannot be sure about, skepticism proves to be an excellent tool to show how biased and incomplete our vision of the world can be; opening the door for myriads of interpretations of the reality, adding to our comprehension of world’s phenomena. Therefore, the question about whether our senses fail us or not has been a cornerstone in Western philosophical thought. Nevertheless, in this discussion we shall refer to two particular philosophers, René Descartes and Agustine of Hippo, who have a direct influence in the argument of being a brain in a vat.
On one hand, in his earlier works, Augustine, focuses on the differences between the sensible and intelligible worlds, reaching the conclusion that our senses depend directly on the intelligible as sensations are related only to those things we can feel. Conversely, the intelligible realm contains what is “truly real”. (Mendelson 6). In Augustine’s words.
“If physical objects please you, praise God for them, but turn back your love to their Creator, lest, in those things that please you, you displease him. If souls please you, let them be loved in God; for in themselves they are mutable, but in him firmly established–without him they would simply cease to exist.” (Augustine IV, xii, 18)
Thus, according to Augustine, these physical objects on which we lean on are nothing but a creation of God and have to be considered transitory objects different than those existing outside of the temporality of the sensible objects. This proposes its share of problems as its thought places a great deal of importance on the soul in the thought process of how our senses imprint on us, leaving the possibility of an empiricist knowledge derived from the sensation and experience as sensation is a quality that depends on the soul, not the body. Thus, the soul feels through the body, the body itself is incapable of feeling. (Miethe 257). Nevertheless, in Augustine’s thought there is a sort of interdependence between mind and senses, since:
“… Apart from the mind-dependence on the senses, how few feelings remain which we know as surely as we know they are alive? … this assurance does not come to us in the way of impressions from the outer world … as when the oar in water appears as broken, towers on the land seem to men on shipboard to be in motion and some many cases of difference between appearance and reality” (Augustine 149).
For this reason, there is in Augustine a dichotomy between appearance and reality, stemming from the fact that our senses can deceive us on the grounds that perceptions are not entirely real and that knowledge is not gained through the senses but thanks to a subject’s rational abilities and its ability of passing judgment about what it sees, understanding them as copies of a greater copy that serve us to approach the world’s phenomena.
On the other hand, Descartes proposes a hypothesis to understand the relation between our mind and our perceptions: the evil demon hypothesis, on which he says that:
“… some malicious demon of the utmost power and cunning has employed all his energies to deceive me. … the sky, the air, the earth, colors, shapes, sounds and all external things are merely delusions of dreams that he has devised to ensnare my judgment.” (Descartes 15).
Accordingly, Descartes considers that this “evil demon” or deceiver, messes with his cognitive faculties, making impossible for him to contemplate things as they are. Hence, Descartes goal is not to consider himself instantly flawed, but establishing that is possible to doubt in the simplest and most evident matters. However, unlike Augustine, Descartes tries to offer a non-theistic option, considering that it might be possible that humans do not come from an all-powerful being, but if that were the case, our inherent imperfection would make us deceivable as well, turning doubt into something necessary and a state of mind. Hence, the evil Genius can be seen as a construction that serves him to doubt of the human’s rational nature, considering human beings prone to error instead of bodies with infallible minds (Newman 3).
“I further notice that the mind does not receive the impressions from all parts of the body immediately, but only from the brain, or perhaps even from one of its smallest parts, to wit, …whenever it is disposed of in the same particular way, conveys the same thing to the mind.” (Descartes 28)
Finally, Descartes opens the contemporary discussion on the labor of the brain as the source of these perceptions, paving the way for a more rational and less ontological consideration regarding the cause of our perceptions.
Consequently, modern epistemology decided to carry the torch Descartes and Augustine left and wondered whether the idea we have constructed for ourselves and our corporality comes from the reality or it is just a series of induced stimuli meant to resemble and reconstructing reality. Hence, Putnam’s experiment can be seen as a revamped version of Descartes’ evil genius argument as intends to ask the possibility of self-recognition even in an environment that supplies the body with all the stimuli it would find in the sensible world.
“… imagine that a human being … has been subjected to an operation by an evil scientist. The person’s brain … has been removed from the body and placed in a vat of nutrients which keeps the brain alive. The nerve endings have been connected to a super-scientific computer that causes the person whose brain it is to have the illusion that everything is perfectly normal. There seem to be people, objects, the sky, etc.; but all the person … is experiencing is the result of electronic impulses traveling from the computer to the nerve endings.” (Putnam 5).
Thus, stemming from its premises, understanding the argument of being a brain in a vat (BIV) can seem hard at the beginning since it seems impossible to define right from the beginning our position in such situation. For instance, if the body grants us perceptions and those perceptions grant are nothing but electric impulses than can be replicated by machines that mean we are living a false reality on which our experiences correspond with being a brain in a vat, which renders impossible the idea of changing that self-reference. Thus, from a non-philosophical perspective, it is impossible to know if we are a BIV.
Moreover, Putnam’s experiment considered that the brains in a vat would be identical to those unvetted, which means they would have the same conceptual frameworks of those in bodies. The only difference between the BIV and a human strives in the fact that to BIV there would be no external objects, which means that even if a vatted brain considers there is an object in front of it, it would not be real, just a simulation of an actual tree that offers no connection between the simulated trees and their real counterparts. Therefore, the solution Putnam proposes heavily on semantics since it relies on the principle of the causal constraint that states that a term refers to an object only when there is an appropriate casual connection between the term and the object it tries to reference (Hickey 2). This means that these BIV, in fact, lack real counterparts to the stimuli they feel which mean that although, they think and say they are not brains in a vat, they will not know for a fact whether they are BIV or not. Therefore:
“The answer is going to be … this: although the people in that possible world can think and ‘say’ any words we can think and say, they cannot … refer to what we can refer to. In particular, they cannot think or say that they are brains in a vat (even by thinking ‘we are brains in a vat’” (Putnam 8)
Conversely, Nozick’s approach to the subject tries to challenge traditional theories of knowledge on which a subject knows the prepositions only if said subject regards them as true, justifying their knowledge in their belief (Fesser 1) Regarding the BIV problem, this would mean that to believe itself human, a subject has to believe in his humanity and the preposition self-justifies itself. Therefore, a subject cannot know he is not a BIV only basing on its belief that it is not. In Nozick’s words:
“A drunk who hallucinates a pink elephant does not know there is a pink elephant there. The elephant being there is not the cause of his believing it there … Since on this view, the causation … of our beliefs is necessary for us to have knowledge.” (Nozick 170)
Hence, the subject relies on a belief related to a situation to assess it situation as a brain in a vat, effectively considering that to be the truth it still will not know it is a BIV since said belief relies on belief-forming processes that might be flawed. Consequently, Nozick’s argument rejects the closure principle by saying that if it were not true that the subject is not a brain in a vat, the subject would still believe he is not. Furthermore, Nozick’s problem can be regarded because the BIV scenario is not based on a justified true belief, but in the reliabilism.
Although differently, G.E. Moore also denies the probability of humans being brains in a vat using his “Here is one hand” argument on which he intends to give an argument against skepticism by raising one hand and then the other.
“… How? By holding up my two hands, and saying, as I make a certain gesture with the right hand, ‘Here is one hand’, and adding, as I make a certain gesture with the left, ‘and here is another’” (Moore 166).
What Professor Moore intended to say is based on an argument of causation, given the fact that he shows one hand, compelling us to believe there is another hand, and then showing it, reaffirming his belief. For this reason, Moore defends the proof of external objects considering them points of reference, using them to demonstrate the existence of the world, rather than doubting of their properties, or their “realness.” In this sense, by stating that if know S, P must be true Moore seems to believe in the worldly references rather than in the philosophical intuitions that accompany skepticism. Consequently, Moore’s response to the BIV argument can seem deceptive since it would accept it is in fact not a BIV basing on the knowledge we have of the world (Black 9). Likewise, in situations on which we are not able of using our knowledge of the reality, the situation changes, since using the body as a form of measurement could not result in beliefs that do not resort to skeptical explanations to work. Therefore, to thoroughly know that we are not a BIV we have to have perceptual experiences regarding the situation as these perceptions for our beliefs, which gives us the ability to represent possible outcomes of the experiences.
To sum up, since the dawn of the philosophical thought, men has wondered about the reality of their perceptions. This has resulted in attributing the decisions of our perceptions to different agents, rather than considering these perceptions are part of the reason. That is why Augustine used the soul as the base of the perceptions since he felt the senses could deceive us, giving us false information about the world surrounding us. Moreover, the same happens with Descartes, who considers that although it is possible that our senses deceive us, we must have a faculty in the body that permits us understanding and using our perceptions. In his case, the brain. This opened a new series of explanations regarding the nature of our thought processes, opening the door for inquiries such as the one we studied today. While Nozick, Putnam, and Moore differ in key points, they all share the position that even if we were brains in a vat, we would not be able to know it since it is not possible to use the body, causal beliefs or semantic references to assess the identity of our perceptions, which leads to the ancient question of whether or senses deceive us or not.
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