Abstracta 5 : 1, pp. 16 – 29, 2009 NAGEL ON CONCEIVABILITY Terence Rajivan Edward Abstract In the sixth chapter of The View from Nowhere, Thomas Nagel aims to identify a form of idealism, to isolate the argument for it and to counter this argument. The position that Nagel takes to be idealist is that what there is must be possibly conceivable by us. In this paper, I show that Nagel has not made a convincing case against this position. I then present an alternative case. In light of this alternative case, we have reason to reject an important example that Nagel offers of a contemporary idealist, namely Donald Davidson. 1. In the sixth chapter of The View from Nowhere, Thomas Nagel draws our attention to a thesis that I shall refer to as the conceivability thesis. According to this thesis, what there is must be possibly conceivable by us. He claims that this thesis is a form of idealism and declares that a number of contemporary philosophers are idealists because they accept it (1986: 90). Nagel seeks to justify rejecting the thesis. First he presents what he takes to be the argument for it. Then he attempts to counter the argument. This paper has three aims. The first is to show that Nagel does not make a convincing case against the argument he uncovers for the conceivability thesis. The second is to show that there is an alternative case that he could have made. The third is to show that, in light of this alternative case, we have reason to reject an important example Nagel gives of a contemporary philosopher who is an idealist, namely Donald Davidson. Before pursuing these aims, I clarify the conceivability thesis. 2. There are at least two notions which are in need of clarification in order to understand the thesis that what there is must be possibly conceivable by us. One of these is the notion of 'us'. Who counts as one of us and who does not? The other notion in need of clarification is that of being possibly conceivable. Nagel contrasts being possibly conceivable by us with being actually conceived of by us and being currently conceivable by us. For instance, after briefly criticizing certain forms of idealism, he writes: T.R. Edward 17 But the form of idealism with which I am concerned isn't based on this mistake: it is not the view that what there is must be actually conceived or even currently conceivable. Rather it is the position that what there is must be possibly conceivable by us, or possibly something for which we could have evidence. (1986: 93) But what does it mean to say that something is merely possibly conceivable by a person as opposed to actually conceived by them or currently conceivable by them? In this section I seek to clarify the notion of us and the notion of being possibly conceivable. Let us begin with the notion of 'us'. Nagel does not define this notion, despite suggesting that a grasp of the criteria for counting someone as us is crucial for understanding the position he has in mind (1986: 90-1). However, while arguing against the conceivability thesis, he does clearly indicate that certain kinds of people are not to be counted as us. People with the permanent mental age of a nine-year-old are not us, for Nagel. His argument involves contrasting us with such people (1986: 95). According to Nagel, we can conceive things that they cannot conceive. Nagel also contrasts us with people he imagines whose mental faculties are superior to his to the extent that the gulf between them and him is comparable to that between him and people with a permanent mental age of nine (1986: 95). According to him, they might be able to conceive things that we cannot conceive. From these two contrasts, one might form the impression that a person only counts as one of us, for Nagel, if they have mental faculties that are not dramatically superior or inferior to his own. This is the understanding of 'us' that I shall work with in this paper. It may be that it is in need of refinement, though. It might not perfectly capture how Nagel uses the term 'us'. Nevertheless, it is adequate for the purposes of this paper. Let us turn now to the notion of being possibly conceivable by a person. The distinction between being actually conceived by a particular person and being currently conceivable by that person is straightforward. Someone might not actually conceive that snow is falling in the vicinity. If they do not think that it is, then they do not actually conceive that it is. Nevertheless, they might have the ability to conceive that snow is falling in the vicinity. If so, then it is currently conceivable to them that snow is falling. What though does it mean for something to be possibly conceivable by a particular person? There Nagel on Conceivability 18 are certain things that a person might not at present have the ability to conceive yet might one day be able to conceive. For example, a person who has never seen snow before might not have the ability to conceive of snow falling. If they are one day shown snow falling and are taught to think of this happening as snow falling, they might then acquire this ability. It is part of our commonsense outlook that in the future a particular person might acquire the ability to conceive of certain things which they cannot currently conceive. Such things are not currently conceivable by the person but they are possibly conceivable by them. All the things that the person can already conceive are also possibly conceivable by the person; it is just that with these things the possibility is already realized. In the quotation above, Nagel attempts to formulate the view that concerns him by writing not just of what must be possibly conceivable by us but also of what we could possibly have evidence for. However, prior to this point in the text, he discusses the view at length without doing this and it is not clear why he mentions possible evidence at all. I do not think he means to add anything significant. The position that Nagel focuses on is that what there is must be possibly conceivable by us. For understanding this thesis, it is important that the following point be kept in mind. If something can only be conceived by a being with mental faculties that are dramatically superior to our own, then it is not possibly conceivable by us. Perhaps a person who is currently one of us can undergo the kind of improvement which enables them to conceive of such a thing. But then they would not be one of us, on Nagel's understanding of 'us'. The conceivability thesis involves denying that there could be superior beings who are able to conceive things that beings with our mental faculties could never conceive. 3. Once Nagel has explained the position that concerns him, he makes an assertion about what an argument in favour of it must show: An argument for this general form of idealism must show that the notion of what cannot be thought about by us or those like us makes no sense. (1986: 93, his emphasis) T.R. Edward 19 The reason why Nagel thinks that such an argument would secure the conceivability thesis is as follows. The only seeming rival to this thesis is the view that there could be some things that are not possibly conceivable by us. This is a genuine rival view if it is intelligible. If it simply does not make sense, then it is not a genuine rival view. The view is only intelligible if there is an intelligible notion of what is not possibly conceivable by us. (In the quotation, Nagel writes of the notion of what cannot be thought about by us. More precisely, he means the notion of what is not possibly conceivable by us.) As such, an argument which shows that there is no intelligible notion of this kind provides us with a good reason to assert that what there is must be possibly conceivable by us. For the putative rival view, that there could be some things which are not possibly conceivably by us, is not a genuine option. Even if it appears at first to be an intelligible view, the argument reveals otherwise. Nagel does not just assert that the conceivability thesis would be supported by an argument which shows that a certain notion does not make sense. He also asserts that it has to be argued for in this way. In the quotation above, he writes as if no other line of argument could ever justify it. I shall not contest this. What I wish to present in this section is the argument that Nagel ascribes to philosophers who endorse the conceivability thesis, before evaluating Nagel's response to it. Here is Nagel's statement of this argument: The argument is this. If we try to make sense of the notion of what we could never conceive, we must use general ideas like that of something existing, or some circumstance obtaining, or something being the case, or something being true. We must suppose that there are aspects of reality to which these concepts that we do possess apply, but to which no other concepts that we could possess apply. To conceive simply that such things may exist is not to conceive of them adequately; and the realist would maintain that everything else about them might be inconceivable to us. The idealist reply is that our completely general ideas of what exists, or is the case, or is true, cannot reach any further than our more specific ideas of kinds of things that can exist, or be the case, or be true. (1986: 93-4, his emphasis) Nagel depicts the justification for the conceivability thesis as hinging on the claim that there is the following entailment relation: if something can be correctly represented using at least one general concept of ours, this entails that every property of this thing can be Nagel on Conceivability 20 represented using only concepts that are within our grasp. To illustrate the thought of such a relation, suppose that a being has a concept that we do not have which is used to identify a type of thing that we have not encountered before, for instance a kind of animal. The being uses this concept to declare that an instance of this type of thing exists. In doing so, they represent the world in a way that uses at least one general concept of ours, namely the concept of existence. Let us suppose that the representation is correct. If so, something has been correctly represented using at least one general concept of ours. For Nagel's opponents, this entails that every property of the thing can be represented using only concepts that are within our grasp, that is, either concepts we currently have or concepts that we could one day acquire without undergoing a dramatic improvement in any of our mental faculties. On the basis of this supposed entailment relation, they claim that what there is must be possibly conceivable by us. When Nagel explains the argument for the conceivability thesis, he does not present any case in favour of this supposed entailment relation. This point will play an important role in my evaluation of Nagel's response. Before moving onto this evaluation, here is the argument in steps. (1) The conceivability thesis is correct if and only if the following view does not make sense: there might be some things which are not possibly conceivable by us. (2) This view only makes sense if the notion of something which is not possibly conceivable by us makes sense. (3) This notion only makes sense if the following claim is true: if something can be correctly represented using at least one general concept of ours, it does not follow that all the properties of this thing can be correctly represented by using only concepts that are within our grasp. (4) But this claim is false. If something can be correctly represented by using at least one general concept of ours, it follows that all the properties of this thing can be correctly represented by using only concepts that are within our grasp. From (3) and (4): T.R. Edward 21 (5) The notion of something which is not possibly conceivable by us does not make sense. From (2) and (5): (6) The view that there could be some things which are not possibly conceivable by us does not make sense. From (6) and (1): (7) What there is must be possibly conceivably by us. Nagel does not himself break the argument down into steps, before specifying any premises or inferences which he is against. From examining what he says though, it becomes clear that the principal clash between himself and his opponents is over (4). After presenting the argument for the conceivability thesis, Nagel gives us a reason to reject (4). It is part of our commonsense outlook that some people cannot understand certain truths because their mental development has not advanced to the point where they can grasp certain concepts. For example, most little children cannot understand many mathematical truths because they do not have the relevant mathematical concepts nor are they at a stage in their mental development when they can be successfully taught these concepts. In light of such cases, it seems that there could be some truths that we too cannot understand because our mental faculties are not advanced enough to grasp certain concepts. Nagel presents cases of this kind in order to support the view that some of what there is might not be possibly conceivable by us (1986: 95). This way of supporting the view involves rejecting the inference that if something can be correctly represented by using at least one general concept of ours, it follows that all the properties of this thing can be correctly represented by using only concepts that are within our grasp. We suppose that there might be aspects of the world that can only be correctly represented by using at least one general concept of ours, such as the concept of existence, but along with some concepts that are simply not within our grasp. Hence Nagel's justification for his view involves rejecting (4). Nagel considers an objection to this justification. It appears to be an objection that he devised himself. He anticipates that someone might make this objection but he does not Nagel on Conceivability 22 present any philosopher as actually making it (1986: 96). I shall not introduce this objection or his response to it, because without doing so it can be shown that Nagel has not done enough to secure his view. Why does any philosopher endorse (4) to begin with? When one turns to the paragraph in Nagel which explains the argument for the conceivability thesis, no grounds are given for this premise. Advocates of the conceivability thesis are depicted as simply asserting that there is a certain entailment relation, even though it is not obvious that there is this entailment relation. This depiction is suspect. Consider the following remark which Nagel makes while introducing the conceivability thesis: The idea that the contents of the universe are limited by our capacity for thought is easily recognized as a philosophical view, which at first sight seems crazily selfimportant given what small and contingent pieces of the universe we are. It is a view that no one would hold except for philosophical reasons that seem to rule out the natural picture. (1986: 92) Given that (4) is glaringly in need of justification, a philosophical reason for the conceivability thesis cannot involve a bald assertion of this premise. It seems then that Nagel has left out a crucial piece of information when telling us the argument for the conceivability thesis. He has left out the reasons that have actually been given for (4). Without this information, we ought not to be convinced by Nagel. Why not? One might think that if Nagel has made a good case against (4), then we can know that any reasons given in favour of (4) are bad ones prior to being made aware of them. But consider again Nagel's case in light of what is said in the quotation above. In this quotation, philosophers who hold the conceivability thesis are depicted as knowingly departing from an intuitive view, or 'natural picture' to use Nagel's term, because they have reasons which they find compelling enough to warrant a departure. Now the case that Nagel makes against (4) is ultimately an explanation of why it is intuitive to reject (4). If someone wanted an explanation of why it is intuitive, one could say what he does: given that there are truths that others cannot understand but we can, surely there might be truths that we too cannot understand. (Note that the claim in the quotation that we are small and contingent pieces of the universe, rather than gods say, is not a different explanation; it just explains the use of 'surely' here.) But there is still room to wonder whether advocates of the conceivability T.R. Edward 23 thesis have a compelling reason in favour of (4), that is, a reason strong enough to warrant departing from the intuitive view. If some philosophers purport to offer reasons of this kind, Nagel needs to show that the reasons offered are not compelling, but all he does is imply that reasons are offered without telling us what they are and without revealing their inadequacy. This is why Nagel's case is unconvincing. It is analogous to a case against determinism which merely explains why it is intuitive to believe in free will. In the final section of this paper, which focuses on Davidson, I shall support the suspicion that Nagel has not considered the reasons that are actually given for (4). Before this section, I shall contest another premise of the argument that Nagel presents for the conceivability thesis. 4. The argument that Nagel isolates for the conceivability thesis is a bad one even if (4) is true. Consider (3) instead: The notion of something which is not possibly conceivable by us only makes sense if the following claim is true: if something can be correctly represented using at least one general concepts of ours, it does not follow that all the properties of this thing can be correctly represented by using only concepts that are within our grasp. Let us grant, for the sake of argument, that advocates of the conceivability thesis are right to assert that the claim following the colon is false. Contrary to (3), we can still form the notion of something that is not possibly conceivable by us. In order to see that this is the case, imagine that two people are playing a game of chess and a child who knows how to play chess is watching. A player resigns. The child asks why. The child is told that it was within the other player's power to achieve checkmate in four moves. Both players then try to explain to the child how. But the child cannot understand the explanation. Demonstrations are given using the board. Still the child cannot understand. The chess players then check to see whether the child can ever understand how it is within a player's power to achieve checkmate. Their tests reveal that the child can sometimes understand how, but only when the scenarios are relatively straightforward. There is something about Nagel on Conceivability 24 the child's mind which means that although they can understand the general idea of it being within a player's power to achieve checkmate in four moves, they cannot ever understand the details of how this is so in a particular match. What is this something about the child's mind? Even if we cannot specify exactly what it is – after all, the relevant psychological knowledge is not commonplace – we can say that the problem is not that the child lacks some concept or other. The child knows how to play chess and so it is possible to construct an explanation of how checkmate can definitely be achieved in four moves using only concepts that the child has grasped, such as the concept of a king, the concept of a move and so on. But the child cannot understand the explanation. From this example, we can see that there is a potential gap between all the correct representations that can be formed using a particular person's repertoire of concepts and all the correct representations that this person can understand. We can thus imagine that superior beings construct some correct representations that we cannot understand even though these representations are constructed using concepts that we have. Suppose then that we grant the entailment relation that Nagel rejects. Contrary to (3), we can still form the notion of something that is not possibly conceivable by us. For even if all the properties of a thing can be correctly represented using concepts that are within our grasp, it may nevertheless be the case that without an improvement in our mental faculties we cannot understand some of these correct representations. And so, there is still room for the thought that there are features of reality which are not possibly conceivable by us. Leaving aside whether or not (4) is acceptable, (3) is false. In the previous section, I claimed that we would expect Nagel to explain how various philosophers have attempted to justify (4) when he presents the argument for the conceivability thesis. Given that (3) is false, and therefore not self-evident, should we not also expect an explanation of how such philosophers have attempted to justify (3)? I think that we should not. Whereas (4) is glaringly in need of justification, it is understandable for a person to not register anything controversial about (3). Examples that can be used to contest (3) do not come to mind so easily. It is understandable then for proponents of the conceivability thesis to simply assert or assume (3), whereas it would be bewildering for them to simply assert (4), since this premise is patently controversial. T.R. Edward 25 5. Nagel regards the conceivability thesis as a form of idealism. Furthermore, he regards it as presupposed by all other forms of idealism. The other forms are characterised by him as specific forms, whereas what he is interested in is characterised as a general form of idealism, since it is presupposed by the specific forms (1986: 91). It is reasonable to doubt whether the conceivability thesis is a form of idealism, whether each form of idealism involves a commitment to it and whether Nagel is right to think that realism involves rejecting this thesis. But so far I have not engaged in these debates. I have remained neutral on these issues and continue to do so below. Nevertheless, the alternative counter that I have presented in the previous section can be used to dispute an important example that Nagel offers of a philosopher who is an idealist. When Nagel makes his case against the conceivability thesis, he refers to Davidson as an example of a thinker who espouses this supposed form of idealism. But he does not present Davidson as ever claiming that what there is must be possibly conceivable by us. Rather he quotes Davidson making a claim that he treats as amounting to an assertion of (4). The claim is this: it is impossible for there to be a truth which can be stated in another language but cannot be stated in our language (1986: 194). But even if we grant that the conceivability thesis is a genuine form of idealism, is Davidson an idealist just because he makes this claim? Nagel has convinced some philosophers to regard Davidson as an idealist (McGinn 1987: 268; Avramides 2006: 237). What I shall show is that we ought to reject this charge of idealism. The claim that Nagel quotes is made by Davidson in his renowned essay 'On the Very Idea of a Conceptual Scheme'. In that essay, Davidson aims to show that the idea of a conceptual scheme does not make sense (1984: 183). He thinks that the intelligibility of this idea depends on the intelligibility of the thought that different groups of people might have different conceptual schemes (1984: 198). Davidson considers four attempted explanations of what it would be for different groups to have completely different schemes, each of which he deems unintelligible (1984: 192-5). He then sets out to show that we cannot even make it intelligible to ourselves how different groups could have partially different schemes. The claim that Nagel quotes emerges from Davidson's treatment of two of the attempts to explain what it is to have a completely different scheme (1984: 193-4). Nagel on Conceivability 26 According to one attempt, a conceptual scheme consists of a set of beliefs that fit with the data of sensation. According to the other attempt, a conceptual scheme consists of a set of beliefs that fit with reality. Both attempted explanations hold that two groups of people have completely different schemes if and only if the beliefs which comprise the conceptual scheme of one group cannot be translated into the language of the other group and vice versa. In response to these attempts, Davidson proposes that to speak of beliefs fitting with either the data of sensation or reality is to say, in a metaphorical way, that the beliefs are true (1984: 194). Consequently, in Davidson's eyes the attempted explanations depend for their intelligibility on the intelligibility of the following thought: there might be truths which are expressible in one language but not in another. Davidson denies the intelligibility of this thought. He does this in the passage that Nagel quotes: The criterion of a conceptual scheme different from our own becomes: largely true but not translatable. The question whether this is a useful criterion is just the question of how well we understand the notion of truth, as applied to language, independent of the notion of translation. The answer is, I think, that we do not understand it independently at all. (Davidson, quoted in Nagel 1986: 94) For Davidson, it cannot be the case that there are truths which can be expressed in a language unfamiliar to us but cannot be expressed in our language. Note that Davidson's use of the term 'our language', which does not feature in this quotation but does elsewhere in his essay, is apt to appear obscure in light of Nagel's use of 'our'. For the people whom Nagel counts as us do not all speak the same language. Which language then does 'our language' refer to? It is tempting to say English, since this is the language that Davidson writes in. However, he clearly does not want to accord a special status to English. He does not want to say that English can be used to express any truth that is expressed in another language, but other languages might not be able to express certain truths that can be expressed in English. It seems that he is happy for 'our language' to be thought of as any natural language (Case 1997: 11). Whichever natural language is taken as 'our language', Davidson believes that this language can be used to express all truths that can be expressed in other languages. T.R. Edward 27 On the basis of his claim that there cannot be truths that are only expressible in certain other languages, Nagel interprets Davidson as asserting the entailment relation proposed in (4): if something can be correctly represented using at least one general concept of ours, it follows that all the properties of this thing can be correctly represented by using only concepts that are within our grasp. Nagel says that Davidson simply has another way of putting this point, in terms of language (1986: 94). Now, before proceeding to defend Davidson against the charge of idealism, it is worth noting how Davidson supports his claim. He appeals to Tarski as providing us with our best intuition about the concept of truth (1984: 194-5). According to him, an implication of this intuition is that every truth can be translated into our language. Some philosophers have discussed this appeal to Tarski (Hacker 1996: 300-1; Soames 2003: 324-330), but Nagel never does. I do not want to go into more detail about it here, only to make the following point. The fact that Nagel does not discuss Davidson's appeal to Tarski supports the suspicion raised in the third section of my paper that Nagel simply does not specify the reasons actually given for (4). If Davidson is asserting (4), he is doing so for a philosophical reason and Nagel does not address this reason. Let us return now to the purpose of this section: to dispute Nagel's charge of idealism against Davidson. The example in the previous section enables us to see how one can respond on behalf of Davidson. Using a vocabulary that the child in the example already has, it is possible to explain how it is within the power of one player to achieve checkmate in four moves. There is no individual piece of terminology involved in this explanation whose meaning eludes the child. Nevertheless, the child cannot understand the explanation. As such, there is a potential gap between which truths can be expressed in a language spoken by a particular person and which of those truths can be grasped by that person. This allows us to envisage the following possibility. There are beings of superior intelligence who speak a language that we do not know and sometimes make true statements in this language that we could never understand without a dramatic improvement in our mental faculties. Nevertheless, it is possible to translate the sentences that are used to express such truths into our language. It is just that we cannot understand these sentences. If there are beings of superior intelligence who speak our language, they Nagel on Conceivability 28 might be able to understand what is being said, but we cannot. When Davidson denies that there might be truths that can only be expressed in other languages, he leaves room for this possibility. Hence he can admit that there could be things that we cannot possibly conceive. He can say, 'We cannot understand some, or all, true statements about such things. Nevertheless, any truth that can be stated in another language can also be stated using our language.' This stance does not occur to Nagel. Nagel tells us that what he takes to be a form of idealism was popular at the time when he was writing. But while making his case against it, he only refers to Davidson as an example of this sort of idealist. Later on in the chapter, Strawson and Wittgenstein are also identified as idealists. The latter is presented as an important source of contemporary idealism (1986: 105). Whether or not Nagel is right about this or right to label these two philosophers as idealists, for now we should reject the charge that Davidson is one. Idealism is not regarded as an attractive metaphysical position within the philosophical culture from which Davidson's work emerges. This means that we should suppose that Davidson too is opposed to idealism unless we encounter evidence that indicates otherwise. There may be evidence of this kind, but Nagel does not provide us with it. Terence Rajivan Edward The University of Manchester x3x7@yahoo.com T.R. Edward 29 References Avramides, A. (2006) 'Thomas Nagel: The View from Nowhere', IN J. Shand (ed.), Central Works of Philosophy, Volume 5: The Twentieth Century: Quine and After, Chesham: Acumen. Case, J. (1997) 'On the Right Idea of a Conceptual Scheme', The Southern Journal of Philosophy, 35, 1-18. Davidson, D. (1984) 'On the Very Idea of a Conceptual Scheme', IN Inquiries into Truth and Interpretation, Oxford: Clarendon Press. Hacker, P. (1996) 'On Davidson's Idea of a Conceptual Scheme', The Philosophical Quarterly, 47, 285-305. McGinn, C. (1987) 'Critical Notice of The View from Nowhere by T. Nagel', Mind, 96, 263-272. Nagel, T. (1986) The View from Nowhere, New York: Oxford University Press. Soames, S. (2003) Philosophical Analysis in the Twentieth Century. Volume 2, The Age of Meaning, Princeton: Princeton University Press.