Elisabetta Falcone

Do you know you're not a brain in a vat? If you don't, should you be troubled?

The Brain in a Vat (BIV) theory encourages one to suppose that an ‘evil scientist’ has put your brain in a vat filled with nutrients and connected your neurons to a super-computer, therefore, all that you are experiencing  is the result of electrical impulses fed by the evil scientist through the computer. One must also suppose that the evil scientist is able to erase any memory of you having your brain removed from your body. Hence, you are completely unaware that you could be living in a matrix. Once we have established the grounds for this theory, we can firmly state that, there is no way one can conclude if this theory is true or false. This is where we see the argument being founded upon academic scepticism. The BIV theory is particularly related to Cartesian scepticism as it descends from Descartes’ Evil Demon hypothesis (Meditations on First Philosophy 1641) which can be simply put in terms of: an evil demon of "utmost power and cunning has employed all his energies in order to deceive me." In this case the sceptic plays on our fear that our brains may be deceived, the argument is evidently founded upon epistemology: is our knowledge real?                  


If we briefly consider the question on the grounds of academic scepticism, we can conclude that the BIV scenario is not something that we should be troubled by, simply due to the fact that we are unable to reach a definite conclusion regarding it; it is futile to be distressed over it. Now that I have established this view, I will consider this theory under multiple fields of reasoning. Ranging from Hilary Putnam’s argument that we cannot doubt the reality we are living in; to more straightforward arguments proposed by Bertrand Russel and G E Moore who consider the certainty of the external world as proof that we are not BIVs. Both David Chalmers and Putnam attempt to explore the idea of separating scepticism from the theory, Putnam further encourages the idea that the theory is self-refuting, whereas Chalmers further provides a metaphysical approach to the hypothesis, through his Matrix Hypothesis idea. We can also consider Descartes’ religious take on the matter.  

Putnam provides a more complex response of semantic externalism (Reason, Truth and History 1981) which explains that we shouldn’t be troubled by the BIV theory; he poses that we could all collectively be BIVs, if we are all in the same reality, then we cannot doubt its existence. When we communicate, even if it might not be in the way we think we’re communicating, but rather through a super-computer; the fundamentality of communication still exists and cannot be doubted by the sceptic. If all the knowledge we share is the same knowledge, then we can widely accept it and not be distressed about the existence of a matrix.                                                                                                         


It can be counterargued that the scenario could pose that only my brain is in a vat, in which case I should be troubled by the fact that I may not be living in the same, or the ‘correct’ reality, as everyone else. Putnam also attempts to argue that we cannot possibly be BIVs. The brains in the BIV reality, can possibly think in the same way we do, but cannot refer to things the same way we might; even if the brains can be defined as conscious and intelligent, it doesn’t mean that they refer to the same things we do. This is where the ideas of causal interaction and the principal of modern logic influence this argument. For us to be acquainted with a concept it is important we have had direct or indirect causal interaction with it. Alfred Tarski offers an example of the principle of modern logic: “snow is white” is true if and only snow is white. Putnam also offers the idea that if I am referring to a “duck”, my concept of one will be different to the one of a BIV because the brain has never had any causal interaction with a duck; I cannot be certain that “duck” means the same thing in both realities.   


However, this view can be challenged by proposing the idea that we were all potentially ‘vatted’ yesterday, and have therefore already had casual interactions with e.g. “ducks”, therefore when we refer to “duck” it is true if and only it is a duck, which it is.  Therefore, Putnam argues that the BIV theory is ‘self-refuting’. The BIV scenario should be separated from scepticism because it assumes that we have brains and neurons, it automatically agrees with general laws from this reality. If the theory is separated from scepticism, then there is nothing to fear from the argument the sceptic is presenting. Again, we cannot be certain that the ‘vatted’ brains have the same experience of “brains” and “neurons” that we do.                                                


Even if his arguments can be easily counterargued by proposing a different BIV scenario, his ideas are complex and based in logical reasoning, ultimately, he presents a convincing argument.


The Cartesian argument attempts to question the existence of an evil being, who in this scenario, put our brains in a vat. This argument is less complex, but still possesses good reasoning when one considers a religious point of view. Descartes was accused of dystheism, when suggesting that God could be a malevolent being, he stated that he cannot be sure that God isn’t deceiving him (meditation I), even if God’s nature is widely accepted to be benevolent. If we look at the BIV hypothesis from a perspective of religion in the 17th century, it could have easily been rejected by people’s strong belief of God’s benevolent and omnipotent nature as the one true Creator. Based on His qualities he wouldn’t put humans in a situation in which they are being deceived.                                                                                                      


However, we can take a more modern approach, in which epistemology pushes us to doubt the nature, or more radically, the existence of God, and allows space for an evil creator. It can also, confidently, be noted that atheists would reject the Cartesian argument. This argument radically depends on one’s religious tendencies, which determines how subjectively convincing one might find it, I don’t particularly find this argument to be very convincing, simply because it uses the concept of a good “God” which in itself is doubtful.                                                                                               


We can also argue that God allows evil to exist in our world, so why wouldn’t there be an evil creator that is not connected to God? To counterargue this, one could say that some evil is allowed to exist due to the fact that it benefits humans and our morality, and the BIV scenario wouldn’t be the type of evil that God would allow, simply because it has no purpose in enriching our lives, it simply cruelly deceives us.

Furthermore, the Russellian response to scepticism (The Problems of Philosophy 2009) can be applied to the BIV scenario. Russel was an empiricist, in which he believes that all our knowledge is derived from our senses. “Sense data” are the sensations and mental images we receive when encountering an object. He rejects scepticism on the grounds of common-sense, in which we can be sure that our judgement and experiences are real but cannot be sure of anything else outside our experiences. Russel simply refused to accept the sceptical argument because his “sense data” was feeding him information from his experiences, which cannot be put into doubt.                                                          


I personally find this argument not to be very convincing among all the other ones presented, because it can simply be argued that the “sense data” is being fed to you by the evil scientist; even if Russell argued that “sense data” is what leads one to believe that they are living in this ‘true’ reality.

A Moorean response is rather simple, first, let’s consider this:

The Argument from Ignorance (AI)

1. I don’t know that I’m not a BIV.

2. If I know that I have hands, then I know that I’m not a BIV.

3. Therefore, I don’t know that I have hands.


Moore created an epistemological argument in which he doesn’t reject scepticism but instead supports ‘common sense’. His simple argument is that if he can see one hand, that exists in the external world, then an external world must exist; this is how he knows he’s not a BIV. Once Moore has established that hands exist as external objects, then I simply know that I am sitting at my desk typing on my laptop. This basic knowledge cannot be proved, but also cannot be challenged by a much more complicated and advanced philosophical sceptical argument, because it is so basic, and philosophers generally agree that external objects do exist.                                                                                      


Some philosophers argue that he can perceive that his hands exist, but he has no knowledge that they do exist. Moore proposes a rather unsatisfactory answer to this sceptic hypothesis, just because one can physically see their hands, it doesn’t automatically correspond to them not being a BIV. This is because it can be argued that the evil genius wants you to believe that you can see your hands or the external world, but it doesn’t mean that they are not all electrical impulses stimulating your brain. Although, the argument does hold some truth in the fact that common-sense could only be challenged if you are sure that you are a BIV, but there is no way the sceptic is able to prove this, therefore common sense still stands.

Chalmers’ response differs to the others as it takes a much more scientific approach to the scenario. Chalmers (similarly to Putnam) attempts to dissociate the idea of a sceptical argument from the BIV theory, or as Chalmers describes it: The Matrix Hypothesis (The Matrix as Metaphysics 2003). If we take an empiricist point of view, then reality is coming from our senses, and our senses are electrical signals interpreted by the brain. Chalmers argues that the BIV hypothesis is not sceptic, but rather, a metaphysical hypothesis, because it deals with the fundamentality of what makes up reality.


If I take the Moorean example and I look at my hands, I can still see them in the external world, I’m simply doubting the matter they are made of. The computational hypothesis goes as far as saying that the fundamentality of what makes things up is ultimately governed by computational algorithms, which is accepted by some physicists.                                                                                                        

What Chalmers is ultimately trying to imply is that the matrix hypothesis is a metaphysical hypothesis in the sense that we have a Creator (Creation hypothesis), and matter that makes up things (binary) that we respond to. We are not sure what scientifically makes up our reality (atoms or binary code) so we can accept that this is our reality. Speaking in terms of physics, we only know so much about what our reality is made of, the idea of a supercomputer could indeed be true.                         


I find that Chalmers’ argument is logical and attempts to go beyond the simple idea of a hypothetical scenario, the BIV shouldn’t be something that we are troubled by, as we know so little about the world that it could be indeed run by binary code.

These broader and more disciplinary dispersed views of the theory seem to reach the same conclusion, they all somewhat agree on the fundamental view that the theory exists and cannot be disproved, but it is not necessary to be troubled by it. The idea that not all these arguments are founded in philosophy, also strengthens the fact that the hypothesis shouldn’t be distressing us. Considering why scepticism is appealing in the first place: our drive to double-check reality. Scepticism can also develop into an ‘auto-immune disease’, which is why we shouldn’t consciously be troubled by the BIV hypothesis and should collectively be building a solid base of widely accepted true knowledge.



Jennifer Nagel (2014) Knowledge: A Very Short Introduction ch.2. Oxford: OUP

Cottingham, J. (Ed.). (2017). Descartes: Meditations on First Philosophy: With Selections from the Objections and Replies (Cambridge Texts in the History of Philosophy). Cambridge: Cambridge University Press. doi:10.1017/9781107416277

INTELECOM (2018) Brain in a vat p1, available at https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=video&cd=1&cad=rja&uact=8&ved=0ahUKEwjIpZnX29joAhVKiFwKHVEBCFAQtwIIKDAA&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DDuDH3aYWeU8&usg=AOvVaw218pHa0-Nmf4Ngpvrqjmdw

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Wireless Philosophy (2016) Philosophy – Epistemology: Three Responses to Scepticism, available at https://www.youtube.com/watch?v=xehTcQeqDWs

Wireless Philosophy (2016) Philosophy – Epistemology: New Responses to Scepticism, available at https://www.youtube.com/watch?v=4cKyPeDYh8w

Putnam, H. (1981). Reason, Truth and History. Cambridge: Cambridge University Press. doi:10.1017/CBO9780511625398

Hilary Putnam (1981) Brains in a vat chapter 1 available at http://ieas.unideb.hu/admin/file_2908.pdf

Bertrand Russel (2009) The problems of Philosophy available at https://www.gutenberg.org/files/5827/5827-h/5827-h.htm

Tim Black (2002) A MOOREAN RESPONSE TO BRAIN-IN-A-VAT SKEPTICISM Australasian Journal of Philosophy 80: 148-163 available at https://www.csun.edu/~tab2595/MRtBIVS.pdf

G E Moore (1925) A Defence of Common Sense http://www.sophia-project.org/uploads/1/3/9/5/13955288/moore_commonsense.pdf

David J Chalmers (2003) The Matrix as Metaphysics available at http://consc.net/papers/matrix.html


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