The Scope of Knowledge
A yet more contemporary response, contextualism, builds upon the previous one by agreeing that we do not know that we do not occupy sceptical worlds even though we do retain knowledge in ordinary contexts.
Contextualists differ from counterfactualists in holding that the sceptic’s second premise is true also, as is their conclusion in the context of their argument (DeRose 1995). In the context of sceptical doubt, sceptical worlds such as that of the vatted brains become relevant alternatives that cannot be ruled out. And if they cannot be ruled out, then we do not retain knowledge of mundane facts with which they compete. But in ordinary contexts free from sceptical doubts, the sceptic’s distant worlds are irrelevant, and our beliefs must vary with the presence or absence of the facts to which they refer only in close possible worlds.
When judges of knowledge claims raise sceptical doubts, they raise the standards for evaluating beliefs; and when beliefs have to be sensitive to facts in the distant worlds of the sceptic, they cannot pass this unusual test. Recognition of such varying standards in different contexts of evaluation allows the contextualist to say that the sceptic’s argument is sound but irrelevant to our ordinary knowledge claims. How better to show the plausibility of the sceptical position while defending the ordinary knower?
Despite this attraction, contextualism fares no better in the end than counterfactualism. It may improve on the latter by allowing that if we cannot know we are not brains in vats, then we cannot know that we are surrounded by tables and chairs. Once more, in the context of the doubt that the antecedent expresses, this conditional is held to be true. But the other problems facing counterfactualism plague contextualism too, and additional ones as well. First, the position still relies on evaluating beliefs in what it holds to be distant possible worlds, and we have seen that this demand is too strong in any context. Some of the most mundane truths that are easiest to know are false only in very distant possible worlds, where there is no telling what we would believe. The counterfactual account makes these the most difficult facts to know. Second, in defending ordinary knowledge the position once more simply assumes that the sceptic’s worlds are distant while admitting that we cannot know they are not actual. This does not satisfy the demand to answer the sceptic by showing that we have knowledge. Third, there is the implausibility of the claim that we can destroy knowledge we have by simply thinking of sceptical alternatives. One unwelcome implication of this claim is that philosophers, who frequently entertain sceptical hypotheses, have so much less knowledge than their more fortunate, if more naive, counterparts in the real world. While ignorance may be bliss in some contexts, pursuing a profession that so systematically substitutes it for knowledge is probably not what young philosophy undergraduates have in mind. Contextualists who may be content to know so much less than anyone else nevertheless had better not advertise their position.
Can we then defend knowledge by rejecting the sceptic’s first premise? Can we claim to know that we are not brains in vats? Can we show that the evidence we have from experience is evidence for the world as we take it to be, and not for
the sceptic’s worlds? How could we know or show this, when experience itself cannot differentiate between the world as we take it to be and the phenomenal world of a brain in a vat? One older answer favoured by some epistemologists is that we know this a priori, that its defence does not require any inductive argument since it could not be false. It is held that we must know it a priori precisely because experience in itself cannot distinguish these worlds and so cannot be the source of this knowledge. Defenders of this tradition give different but related explanations of how we have this a priori knowledge, of how we can know that the way something appears, for example, is necessarily evidence for how we take it to be. Many of the arguments here begin from an account of how we learn to understand the terms in our language, how we learn to use them correctly or to interpret their use by others (Hamlyn 1970, ch. 3). If we learn to pick out tables, for example, by how they appear to us, how they look and feel, then it must be correct that whatever looks and feels to us continuously in those ways must be tables, or at least that such looks and feels are necessarily evidence for the presence of tables. In the language game in which we apply the term ‘table’ to tables, such ways of appearing are criteria for the correct use of this term. We therefore cannot all be mistaken in this use based on these experiences any more than we could all be mistaken in the way we play chess. Tables are whatever we call tables based on correct application of the term, and correct application is determined by the agreed upon criteria, in this case certain ways of appearing. Thus, these ways of appearing are necessarily evidence for tables and for the properties that define them to be tables. We can neither use the term correctly without accepting these criteria nor interpret its use by others without typically ascribing true beliefs about tables to them. Likewise, of course, for other middle-sized objects and their properties.
Is this argument sound? What it really establishes is only the way we must initially conceive of things. Once we develop the notion of objects whose properties are independent of our experiences and beliefs, once we develop theories of how these properties cause our experiences, and once we see that our experiences can mislead us as to the real properties that cause them, the possibility of wholesale error becomes intelligible. In fact this possibility is entailed by the notion of independence that defines the concept of realism about objects and their properties. That real properties are independent of the ways they appear and the beliefs they cause means that these appearances and beliefs can be misleading and false. Once we recognise the possibility of wholesale error on our part, we need not necessarily ascribe mostly true beliefs to others (although we will ordinarily do so). If, for example, we were to see some brains in vats and understood their situation, we would not ascribe to them mostly true beliefs about the objects around them. To interpret the language of others, we need to explain their utterances, but truth of the beliefs expressed need not necessarily enter into the majority of these explanations. Nor will we explain the brains’ utterances as true of phenomenal objects instead of false of real ones, since they will have the same concept of real objects as we do and will intend to refer to them and their properties. What we and the brains take to be evidence for the objective properties of real objects cannot dictate what those properties are. Our shared concept of chess may determine the nature of that game, but this is what distinguishes games from reality.
Thus, premises about how we learn and interpret our language do not show that the evidence we have for our beliefs about real objects must necessarily be evidence for their objective properties as we take them to be. Is this notion of criteria as necessary evidence short of entailment even coherent? If we do not do away with real objects and their properties by reducing them to experiences or appearances, can the latter nevertheless necessarily be evidence for the former? To say that appearances are necessarily evidence for real properties is to say that they are evidence in all possible worlds. But in a world of brains in vats in which the brains were informed or knew of their own situation, their experiences would not be evidence of objects as we take them to be. This would be true of any sceptical world believed to be such by its victims. Such worlds are possible. The sceptic’s descriptions of them do not involve logical contradictions. We could even grant that we could not all be brains in vats, but that would leave open the possibility that any one of us is and could possibly be informed of this by our programmers. Thus, there is no necessary connection between experiential evidence and the real properties of objects. Do we have any a priori knowledge of reality, as opposed to that which reflects only definitions of terms, including logical connectives and operators? Is there any a priori insight into the necessary structure of reality, knowledge of what is real but not contingent, that needs no inductive confirmation? Well-worn examples that seem to express such knowledge include the claims that nothing can be red and green all over and that, if A is taller than B, and B is taller than C, then A is taller than C (Bonjour 1998, pp. 100–3). It turns out, however, that such examples express lack of experience or imagination, instead of a priori insight into necessary truth. When I was much younger and clothing styles were much different, I owned an iridescent raincoat that looked red and green (as well as tan) all over. Whether the effect was achieved with discrete red and green threads is irrelevant here, since on most accounts of colour, whatever looks a certain colour to normal observers in normal conditions is that colour.