Response to Brain in a Vat

Argument

Jeffrey Engelhardt

So, here we are, and why are we here? That is, why have you come to a philosophy conference? You come to hear profound and eternal truths. And, as I see your eyes are glazing over, and you’ve had your fill today of such stuffs, I’ll be relating just this one eternal truth that follows, so wake up for the next minute, then you’ll sleep more easily knowing that (reveal poster board reading):

“Snow is white” is True if, and only if, snow is white.

We credit this awe-inspiring revelation to Alfred Tarski, from the article “Language, Meaning, and Truth.” Although it may seem, to the person who has not yet shaken his head in disgust at a useless philosophical conundrum, that this sentence tells us nothing, it is one way of wording the motto for a realist theory of truth. The reason that “’snow is white’ if, and only if, snow is white” seems so banal is because the realist theory of truth is consistent with an everyday definition of truth. So, from Blackwell publishing’s Introduction to Philosophical Logic, “Realism is the thesis that the world exists and has its character independently of any knowledge or experience of it, so that sentences about the world are either determinately true or false in virtue of the way things are in the world, whether or not we know or can come to know how things are in the world, and therefore independently of whether or not we can know the truth-value of those sentences That is, the realist theory of truth we’ll be speaking about entails the following

· Objects are mind-independent. Thus, this podium and these papers exist independently from my mind and my thoughts.

· There is one and only one TRUTH.

· The unique Truth is a description of objects that corresponds to the actual objects. Since objects exist independently from my mind, and since there is unique Truth, it seems reasonable to say that the unique Truth we speak of corresponds to the way that objects exist in actuality. Thus, if a speaker is boring, the one and truthful description of that speaker is “speaker is boring.” And, the sentence, “snow is white” is true if, and only if, snow is white.

(by the way, for a readable introduction to a realist theory of truth, I recommend William P. Alston’s A Realist Conception of Truth).

Now, two minutes of my life out of the way, I’d like to reveal what else this paper assumes. The following is a list of what I think we need to assume – beyond that we all speak the same language and other everyday assumptions – before we can get to what is on the verge of interesting in this paper. Of course, this list is incomplete and the reasons I give for my assumptions are not very convincing, but here we go:

In order to assert what we did a moment ago about the whiteness of snow, we assume that truth exists. If one of you reveals to me that it does not, I’ll have to…call Tarski and tell him that snow is not white. Furthermore, I’d like to assume that a sentence is the standard bearer of meaning; some people argue that meaning is not found in sentences but in the parts of sentences or the relations of sentences…we’ll assume, akin to the everyday notion of meaning in language, that a sentence has the meaning of the predication of its subject. Also, since we’re talking about objects that exist outside of the mind, let’s ignore the endless debate about degrees of existing and whether unicorns or Sherlock Holmes exist. Rather, let’s stick to concrete objects in space and time. And, our theory entails that Truth is discovered, not made. So, if the Earth revolves around the sun, it is not true, no matter how many people believe it, that the sun revolves around the Earth. Truth exists as it does without regard for our beliefs. And, finally, we assume that this singular Truth is discovered through rational thought; otherwise, I would not appeal to reason to understand Truth.

So, we have this theory of truth we call the realist theory of truth, and we are aware of what assumptions we’ve made in order to “discover” this theory of truth, and what assumptions we need to make in order to talk about this. So, we just need something to talk about.

That’s easy, because there’s a problem. Philosophers and all other kinds of jerks say that this theory of truth we were just talking about allows for the possibility that Truth is unavailable to us. Those who question the possibilities of knowing Truth in the realist theory of Truth say, “A realist theory of Truth says there is one and only one truth and that Truth is a description of objects that corresponds to the reality of objects that exist outside of the mind.” And a critic of the realist theory of truth responds, “But, all the information about “reality” that we receive is filtered through our senses; thus, our apprehension of the real world – that is, the world of objects to which a description that is true would correspond to – is always mediated, never pure, and thus always incapable of discovering a description that could be called True in a realist theory of Truth." For example, while I might think that Jersey City is a city on the planet Mars, and in reality it is a city on the planet Earth, since I have no pure connection with reality –for, all my interaction with reality is mediated by my senses – I am unable to verify the Truth or untruth of my statement. And, since I could neither verify nor disprove the truth of my statement, detractors of the realist theory of Truth say that it is a theory of truth that denies the possibility of knowledge.

Notice that this does not assail our theory of Truth as a theory of Truth – although there are many challenges to that – but, rather, this is a problem of the epistemic possibilities of our theory of Truth. So, while the description of Truth that the realist theory of Truth postulates might be accurate, the critics point out that such a theory may deny philosophers the possibility of ever knowing any Truth with certainty. One example of this claim is given by Harvard philosopher Donald Davidson in the article, “A Coherence Theory of Truth and Knowledge;” Davidson says the notion of objective Truth involves a problem of verification such that if there were an objective theory of Truth, it would need to be verified by a confrontation between reality and our beliefs, and, Davidson continues, “the idea of such a confrontation is absurd.” And, another, more vivid, challenge of the same sort comes from Oxford scholar Hilary Putnam. This is the argument I will analyze today. Imagine: one night, while I slept, an evil genius snuck into my home and stole my brain. He preserves my brain in a vat of nutrient solution, while electrodes feed it neural stimulations that produce the kinds of sensory impressions and thoughts I would have if I were an ordinary embodied human being. This is called Putnam’s “Brain-in-a-vat argument.”

If this were the case, all those things that I take to be true on the realist conception of truth would be false. For, I would not be perceiving the things that I would think myself to be perceiving. For example, if I were a brain-in-a-vat, and I wanted to offer the description of snow as “snow is white,” even if snow is white, the snow I am thinking of is not snow, nor is it white. For, the snow that I am thinking of is actually just the image of snow transmitted to my brain via the electrodes with the property of white. And, says Putnam, the problem reaches further. While, as a human with both a brain and a body, I doubt that I am a brain-in-a-vat, I have no way of proving that I am not; and, if I subscribe to the realist theory of Truth, then I have to accept that I might be a brain-in-a-vat, or that I am in any other situation where the truth is inaccessible to my faculties. So, the problem of the brain-in-a-vat is not about whether or not I am actually in a vat; it questions whether or not Truth, on a realist theory of Truth, is accessible.

First, we have to establish a definition of knowing which we can use when we talk about “knowing the Truth.” As with the rest of this paper, I would like to use the definition that is most consistent with our traditional ideas. Therefore, we should say that knowing is having sufficient reasons to believe that some idea is true, when that actually is true. So, knowing is believing, for good reasons, that a description of an object or objects that exist outside of the mind corresponds to the actual object or objects that exist outside the mind when the description does correspond to the actual object or objects. So, one knows when his or her belief corresponds to the unique Truth. Then, we say that believing the realist theory of truth is True, when it is True in reality, is the same as knowing the realist theory of Truth is True. And, we say that if the realist theory is True, we who believe it to be True also know it to be true. But, then, how does one know that he knows? For, I might have various reasons to believe something that is not True, and so think that I know when in reality I do not. Well, even if I do not know when I know, if I have sufficient reasons to believe that I know and sufficient reasons to act on that belief, I can say that this is a type of knowing, provided that what I believe is consistent with the unique Truth. For, I am not arguing, here, that we can know when we know. Rather, I want to address the claims that it may be impossible to know in a realist theory of Truth. But, if we don’t know the unique Truth, how can we verify that we know that we know? This is the crux of the opposing argument. If we can’t know reality then we can neither know nor know that we know. And, while the realist theory of Truth might be True, critics argue that if it is True, we may be unable to know the unique Truth.

Second, I want to return to the tenets of the Realist theory of truth to consider Putnam’s argument. The realist theory of Truth hypothesizes that there is a singular Truth. This singular Truth is a description of objects that exist outside the mind that corresponds to the actuality of objects that exist outside the mind. Putnam argues that if all our senses are deceived into believing that a world that does not exist – the world transmitted through the electrodes – then the realist theory of truth disallows that we might know Truth. I think that with Putnam’s argument and the tenets of the realist theory of Truth juxtaposed, it is easy to see where the problems in Putnam’s argument lie.

I’d like to consider the brain-in-a-vat and all other claims that a realist theory of truth denies humans access to Truth, at the crux of the argument: that the realist theory of truth cannot provide a manner of discovering truth. One reason I think the realist theory of Truth works is because it postulates that objects exist independently from the mind. Although I agree that our experience of these extra-mental objects is mediated by our senses, the realist theory of Tuth never postulates that our senses are our only faculty for reaching truth. In fact, we assumed at the outset that rational thought is our primary tool for discovering Truth. Now, since Truth is a description of objects that exist OUTSIDE of the mind, I’d like to suggest that misinterpretation of sensations and mistaken sensation of experiences occurs inside the mind. In fact, this is precisely what detractors of the realist conception of Truth assert, that our senses mediate our experience of reality, and so taint our experience of reality, thus locking us out of the True description of extra-mental objects. But, rather than suggest that misinterpretations and mistaken sensations are a division between our descriptions of extra-mental objects and the True description of extra-mental objects, I suggest that descriptions that rely on misinterpreted sensations and mistaken sensations are truth-neutral and truth-value-less (for those of you familiar with work of Saul Kripke, these descriptions would fall into the “truth-gaps”). They are truth-neutral and truth-value-less because they are descriptions of entities within the mind. When I mistakenly believe that Jersey City is a city on the planet Mars, it is not an actual city on Mars that my thoughts correspond to, but an imagined city. The city I describe is not an object existing outside my mind, therefore my description of such a city is unrelated to the real objects described in the realist theory of Truth, which regards only the unique description that corresponds to the actual world of extra-mental objects.

This demands that, for the brain-in-a-vat argument, a distinction be made between those entities that are within my mind that I perceive to be in reality and those that actually do exist in reality. Some have suggested that a mind would be able to make this distinction and so would not be taken in by the evil genius of the brain-in-a-vat argument, thus retaining the ability to assert True descriptions about objects outside the mind. I disagree with this rebuttal: The evil genius is a genius, she would see to it that your brain be unable to distinguish between the transmitted experiences and the experiences of ordinary life. Rather, I suggest that while a brain-in-a-vat or even a brain-in-a-human might not be able to distinguish between actual experiences and simulated experiences, it does not matter. The distinction between the two is maintained in that one is included in the unique truth – since it concerns actual objects – and the other is unrelated to the unique truth – because it concerns entities that exist only in one’s mind. Therefore, that the brain-in-a-vat cannot distinguish between the two does not change the Truth that one is truth-value-less and the other must be a description that corresponds to the actual objects outside the mind in order to be True. This might seem to suggest gloomy circumstances for the brain-in-a-vat, and indeed for all of us if we can’t distinguish between real and imagined objects, but we will discuss that later on.

First, let’s apply the distinctions we made between imagined entities and actual objects and statements corresponding or not corresponding to the unique Truth and truth-value-less statements to the brain-in-a-vat argument. In the brain-in-a-vat argument, the entities that a brain-in-a-vat would describe exist only in the mind. Therefore, as with the Martian city of Jersey City, the descriptions that a brain-in-a-vat offers are truth-neutral and truth-value-less. If Putnam wanted to show that there exists a situation in which all statements are false in the realist theory of truth, he would have to create such a situation where the statements are descriptions of objects that exist outside the mind, and that are impossible for humans to truthfully describe (I do not suggest that this is impossible, only that this is NOT what Putnam did).

Now, only asserting that descriptions based on misinterpretations of senses or mistaken sensations are truth-neutral and truth-value-less does not dislodge the suggestions that Truth is unavailable in the realist theory of Truth. In fact, such a suggestion seems to support the claim of the critics. And it would, were it not for the saving grace again of the postulate that objects exist outside the mind. Critics of the realist theory of truth argue that if the realist theory of truth is true, then we have no way of knowing the truth because our faculties for interacting with reality are impure. The antecedent to this argument, though, denies the consequent. This criticism says that if we have truthfully described the reality of Truth when we postulate the realist theory of truth, then we are helpless to know Truth. We could simplify this criticism to say, “If we know truth, then we can’t know truth.” In order to know, or know that I know, or know that I know that I know, I have to have a single thing that I know upon which I can build the rest of my knowing. This single part of the Truth that can provide the foundation for all the rest of my knowing is given: of course, it is the realist theory of Truth! The critics of the realist theory of Truth attack only the epistemic possibilities in the theory, arguing that we cannot know. But, if we need a primary Truth to build Truth upon Truth in a theory of Truth, how might we begin, assuming that we are operating within a realist theory of Truth? Of course, we have already assumed that the realist theory of Truth is True! That becomes our first Truth. While this may seem like a question-begging argument, it is not. For, the task is not to defend the realist theory of Truth as a theory of Truth, but to defend the epistemic possibilities within the realist theory of Truth. The critics assume the theory is True in order to criticize the possibilities of knowing within the theory, so it is appropriate to hold the same assumption when responding to the criticism.

If we can describe how the realist theory of Truth was discovered, and we suppose that the realist theory of Truth is True, then we know how to discover Truth: by the same method with which we discovered the realist method of Truth, which we assume is True. Because, when we are told that the realist theory of Truth is True, we are simultaneously told another Truth: that the logic we used to discover the realist theory of Truth preserves Truth. Since we are able to find one Truth by means of rational thought, it seems that we should be able to apply this logic elsewhere. Therefore, when the critic of the realist theory of truth allows that the realist theory of truth is true only to add that we are rendered helpless to find such a truth, we know better. We know that such a critic has told us exactly how to find the true description, namely, by the same method as was used to find the realist theory of Truth, which the critic just told us is True. Therefore, and finally, we arrive at the response to the brain-in-a-vat argument. The brain-in-a-vat argument asks if the realist theory of truth is true, and you are a brain-in-a-vat, how could you know that you are or are not a brain-in-a-vat? We respond, “I need only to believe that the realist theory of Truth is True. Since I was just told that the realist theory of Truth is in fact True, I know, by our definition of knowing, one True thing. If I were a brain in a vat, I would not know that the realist theory of Truth is True; for, the very nature of being a brain-in-a-vat, as Putnam describes it, denies the possibility that I might know Truth. Since that the realist theory of Truth is True is Truth, then I must not be in a vat because I have access to the Truth, which Putnam says is denied me when I’m in the vat. But, if I learned that the realist theory of Truth is True before I entered the vat or if the evil genius equipped me with just this one Truth, and I am a brain-in-a-vat, and I know that the realist theory of Truth is True, then I can follow the same process by which I discovered that the realist theory of Truth is True to decide whether or not I am a brain-in-a-vat.” And, for those sad souls that do not know that the realist theory of Truth is True, each is unaware that he or she could indeed be a brain-in-a-vat.

Of course, there are problems in this argument. The most detrimental of these concerns my definition of thought. I, (even I!) think it is much less than convincing, but I also think it can work, for now, since it appeals to an everyday sense of knowing that can work with the realist theory of Truth. Also, I assume that the method for finding one part of the unique Truth would also be the method for finding other parts of the unique Truth. This goes in hand-in-hand with the assumption that the realist theory of Truth was discovered by logical thought and that logical thought alone discovered it. Also, I assume that the evil genius would allow us the capability for logic, not altering our brain when placing it in the vat – which, since she is a genius, she might think of, but Putnam never mentioned it. But, these problems in my argument do not alter the problems in the arguments of those opposed to the realist theory of truth: those arguments fail to distinguish between entities within the mind and objects existing independently from the mind; and they assume that one Truth is known when they assert that Truth is unknown or unknowable.

**Since this response was written, Jeff's girlfriend has informed him that, not only is he a brain in a vat, he's a jerk.**

Heckle Jeff in his vat at 3engelhard_J@spc.edu