Frege's Unthinkable Thoughts This is the penultimate draft of a paper published in the Proceedings of the Aristotelian Society. For the published version see: https://doi.org/10.1093/arisoc/aox011 Lukas Skiba∗ Institute of Philosophy University of Hamburg Von-Melle Park 6 20146 Hamburg Germany Abstract There are two common reactions to Frege's claim that some senses and thoughts are private. Privatists accept both private senses and thoughts, while Intersubjectivists don't accept either. Strikingly, both sides agree on a pair of tacit assumptions. First, that private senses automatically give rise to private thoughts. Second, that private senses and thoughts are the most problematic entities to which Frege's remarks on privacy give rise. The aim of this paper is to show that both assumptions are mistaken. Against the second assumption, I argue that if private senses give rise to private thoughts they also give rise to more problematic entities, namely unthinkable thoughts. Against the first assumption, I argue that a conception of Fregean thoughts as intrinsically unstructured entities can accept private senses without having to accept private thoughts. This motivates a so far neglected, reconciliatory position between privatism and intersubjectivism according to which all thoughts are public while some senses are private. ∗Email: lukas.skiba@uni-hamburg.de I Fregean Privacy. Frege claims that the first person pronoun 'I' gives rise to senses and thoughts which are private in that they can only be grasped by a single subject:1 [E]veryone is presented to himself in a special and primitive way, in which he is presented to no one else. So, whenDr. Lauben has the thought that he waswounded, hewill probably be basing it on the primitiveway inwhich he is presented to himself. And only Dr. Lauben himself can grasp thoughts specified in this way. (1918, p. 359) In the literature, we find two diametrically opposed reactions to this passage. Intersubjectivists maintain that 'nothing could be more out of spirit of Frege's account of sense and thought than an incommunicable, private thought' (Perry 1977, p. 474; see also Geach's preface in Frege 1977, p. viii). On the other hand, there is a growing number of privatists -most notably Evans (1981), Noonan (1984), Kripke (2008), Künne (2010)-who regard the passage as the unproblematic upshot of a Fregean account of personal pronouns. What is striking about the dispute is that both sides agree on a pair of tacit assumptions. Note that Frege is making two claims in the above passage: Private Senses. For each subject x there is a sense which only x can grasp, a sense x can express with the first person pronoun 'I'. Private Thoughts. For each subject x there are many thoughts which only x can grasp, thoughts which x can express with sentences containing the first person pronoun 'I'. Now, the first shared assumption is that private senses immediately give rise to private thoughts. In so far as Frege can be seen as arguing for this transition at all, his argument is enthymematic. The missing premiss, implicitly accepted by both intersubjectivists and privatists, can be spelled out as follows: Contagious Privacy. If a sense σ is private to x then every thought containing σ is also private to x. The second shared assumption is that private senses and private thoughts are the most controversial entities to which Frege is committed as a result of his remarks on privacy. 1At least this is the standard interpretation of the following passage, see Perry 1977; Dummett 1981, Ch. 6; Evans 1981; McDowell 1984; Noonan 1984; Heck 2002; Kripke 2008; Künne 2010; Textor 2015. For dissenting voices see May 2006 and Longworth Manuscript. 1 This paper aims to undermine both assumptions. In §II, I argue against the second assumption: developing an undeservedly neglected observation by Künne, I argue that if private senses really lead to private thoughts via Contagious Privacy then they also lead to unthinkable thoughts which contradict Frege's conception of what a thought is. In §III, I argue against the first assumption: adopting an (independently motivated) conception of Fregean thoughts as lacking a unique intrinsic structure allows us to reject Contagious Privacy. This allows us to avoid commitment to unthinkable thoughts and moreover paves the way for a so far neglected, reconciliatory position between intersubjectivism and privatism according to which all thoughts are intersubjectively available while some senses are private. II From Private Thoughts to Unthinkable Thoughts. Not every Fregean thought is in fact the content of a belief, a desire or some other propositional attitude. Many thoughts are simply too boring to ever be entertained. But it is generally accepted that each Fregean thought can be the content of a propositional attitude: For Frege, the notion of a thought is fundamentally a cognitive one. [...] Thoughts, that is, remain for Frege 'possible contents of judgement', to use the terminology of Begriffsschrift, or, to use more modern terminology, possible contents of propositional attitudes. (Heck and May 2008, p. 23) Given that all thoughts are possible contents of propositional attitudes, and in particular possible contents of judgement, all thoughts must be graspable. For Frege is aware that making a judgement requires grasping the thought which serves as the content of the judgement (see 1915, p. 251). Frege's conception of thoughts is thus characterized by the following principle: Thoughts as Thinkables. Every thought can be grasped. Importantly, this principle is acknowledged even by privatists: Künne characterises Frege's conception of thought as that 'that of a potential content of certain cognitive acts and states' (2010, p. 209, my translation). And he criticizes Church's translating 'Gedanke' as 'proposition' because it 'threatens to obfuscate that Fregean thoughts are essentially [ihrem Wesen nach] potential contents of thinking' (2010, p. 209, fn. 82, my translation). Noonan says that 'the idea of a thought existing but unavailable to be thought by any thinking being should surely be rejected' (1984, p. 205). According to Evans, thoughts are ways of thinking about truth-values (1981, §2). A way in which no one can possibly 2 think about a truth-value is not a way of thinking about a truth-value, hence Evans is committed to the principle too. That privatists should subscribe to Thoughts as Thinkables is not too surprising. After all there is no obvious conflict between the doctrines. Thoughts as Thinkables doesn't require that every thought can be thought by several subjects, just that it can be thought by at least one. The actual conflict emerges once we consider the question under which circumstances some given senses compose a thought. After distinguishing between saturated and unsaturated sense components Frege endorses the following sufficient condition (which he also puts forward as a necessary condition in 1892a, p. 193): [A]ny component of the one kind together with any component of the other kind will form a thought. (1906b, p. 187) Taking into account that unsaturated senses can belong to different levels, Frege's condition should be understood as requiring that the senses are of logical types which are appropriately related. The sense of a singular term, for instance, needs to be combined with the sense of a first level-predicate, such as 'x is wounded', to form a thought, not with that of a second-level predicate, such as the universal quantifier. So, generalizing slightly and putting the point in terms of appropriately related logical types rather than the saturated/unsaturated distinction, Frege endorses the following principle of thought composition: Thought Composition. Any tuple of senses < σ1, . . . , σn > composes a thought iff the senses in < σ1, . . . , σn > belong to appropriately related logical types. The principle entails that the sense of a two-place first-level predicate and two senses of singular terms will compose a thought. Apart from belonging to the right types, there is no further condition that the sense components must meet. Now the problem with Frege's remarks on privacy is that when Private Senses and Contagious Privacy are combined with Thought Composition then they contradict Thoughts as Thinkables by entailing the existence of an unthinkable thought. Consider the sense which Lauben expresses when he uses the first person pronoun. We will use the expression '[ILauben]' to refer to this sense. By Private Senses, [ILauben] is private to Lauben. In other words, for any subject to grasp [ILauben] the subject has to be identical to Lauben. Similarly, by Private Senses, the sense which Peter expresses with 'I', [IPeter], is private to Peter. For any subject to grasp [IPeter] the subject has to be identical to Peter. Now consider the triple of senses <[ILauben], [x is taller than y], [IPeter]>. By Thought Composition this triple of senses composes a thought. For [x is taller than y] is 3 the sense of a two-place first level predicate, and [ILauben] and [IPeter] are the senses of singular terms. Call the thought that results from this composition T . The thought T is unthinkable; it cannot be grasped by anyone. For it contains a sense private to Lauben [ILauben], and a sense private to Peter, [IPeter]. Given Contagious Privacy the thought T thus has the following property: for any subject to grasp T , the subject has to be identical to Lauben and has to be identical to Peter. Given that Lauben and Peter are in fact distinct, it is impossible for any subject to be identical to both Lauben and Peter. Therefore it is impossible for any subject to grasp T which contradicts Thoughts as Thinkables. The crucial observation behind this argument has already been made by Künne (1997, p. 58). He remarks, somewhat in passing, that if we conjoin the thought expressed by, say, Lauben's utterance of 'I was wounded' with that expressed by Peter's utterance of the same sentence then we get a thought no one can grasp. The present version of the argument makes the problem more acute. If all unthinkable thoughts had the form of the one envisaged by Künne, then we could sacrifice Thoughts as Thinkables in the hope of saving its spirit in the form of a weaker principle which maintains that all atomic thoughts are thinkable. The present formulation of the argument shows that this hope would be vain. Künne is an exception among privatists in that he is aware of the commitment to unthinkable thoughts. But he is no exception as far as the shared assumptions identified in §1 is concerned. For in his 1997 he doesn't seem to think that there is anything too troubling about unthinkable thoughts. That he doesn't find them troubling is somewhat surprising, given that we have seen him to unreservedly ascribe Thoughts as Thinkables to Frege in his 2010. In any case, neither he nor the other privatists offer a resolution to the conflict between this principle and Frege's remarks on privacy. This is just what I will do in the rest of this paper. III Private Senses without Private Thoughts. We have seen that Private Senses, Contagious Privacy, Thought Composition, and Thoughts as Thinkables are jointly inconsistent. Evidently, there is more than one way to restore consistency in Frege's theory. The option I want to pursue here is to reject Contagious Privacy. The main aim is to show that, perhaps contrary to first appearances, this is a live option which merits further investigation. A final verdict will have to be based on a careful weighing up of the pros and cons of each of the four possible strategies which goes beyond the scope of this paper. For now, let me just briefly note some of the advantages of the present strategy. First, it is a good thing if Fregeans can continue to elucidate their conception thoughts with the help of Thoughts as Thinkables. What is more, allowing for unthinkable thoughts 4 would create conflicts with other Fregean doctrines. Frege holds that the word 'true' (and variants thereof) are in principle dispensable (see 1918, p. 356). This would seem to entail that every judgement that can be expressed with the help of 'true' can also be expressed without it. Indeed, Frege thinks for example that 'p' and 'the thought that p is true' express the same thought (see 1892b, p. 164). If we allowed for unthinkable thoughts, however, there would be a clear counterexample to the dispensability claim. If it exists, we can judge the thought T to be true and express this judgement by saying 'T is true'. But in this case there can't be a corresponding judgement that can be expressed without the help of 'true': by construction, the thought T cannot itself be the content of any judgement. Second, sticking to Thought Composition allows us to retain Frege's answer to the question of the unity of the thought: how is it that we express a unified thought, capable of being true or false, rather than a mere collection of senses when we say, for instance, 'Lauben is taller thanPeter'? For Frege, the answer is that the sentence contains expressions whose senses are of the right logical type to hold together without a link (see 1892a, p. 193). He couldn't answer this way if belonging to the right logical types wasn't sufficient for some senses to compose a thought. For then it would be possible for there to be some senses < σ1, σ2, σ3 > which fail to compose a thought, despite the fact that σ1 and σ3 are senses of singular terms, just as [Lauben] and [Peter], and σ2 is the sense of a two-place first-level predicate, just as [x is taller than y]. We would be entitled to ask what difference there is between < σ1, σ2, σ3 > and < [Lauben], [x is taller than y], [Peter] > which accounts for the fact that the latter senses, but not the former, compose a thought. Frege would then be in the danger of having to admit that, after all, there must be some additional link glueing [Lauben], [x is taller than y], and [Peter] together, thereby rendering him susceptible to exactly the kind of Bradleyan regress his original account aims to avoid. Of course, we could also use brute force and stipulate that senses only compose a thought if they are of the right logical type and can all be grasped by a single subject. But note that this would have the awkward consequence that thoughts would no longer be closed under logical operations (such as conjunction, as brought out by Künne's version of the above argument). Finally, as we shall see at the end of this section, preserving Private Senses will turn out to have a pay-off typically only associated with private thoughts. In contrast, there is an elegant way to exploit an independently motivated conception of Fregean thoughts in order to reject Contagious Privacy. To see how, let us consider on which general view concerning Fregean thoughts Contagious Privacy depends. A good source of support is a Dummettian view which subscribes to the following 5 principle (see 1981, Ch. 15): Unique Analysis. Every thought has a unique analysis into constituent senses. In asserting this pinciple, Dummett doesn't mean to deny that Fregean thoughts admit of multiple decompositons. But he maintains that for each thought there is a unique route via which every grasp of the thought must proceed. The unique analysis of a thought lays bare a collection of senses (the constituent senses) which are such that the grasp of the thought must proceed via a grasp of them. Unique Analysis indeed supports Contagious Privacy. For if the thought expressed by Lauben's utterance of 'I am wounded' has a unique analysis it would surely have to be: <[ILauben], [x is wounded]> If [ILauben] is a constituent sense of the thought expressed by 'I am wounded' and if only Lauben can grasp this constituent, then only Lauben can grasp the thought. However, the Dummettian conception of thoughts is very controversial. Many commentators believe that Fregean thoughts do not allow for a unique analysis. Instead they think of thoughts as entities which are 'compositionally polymorphous' (Hodes 1982, p. 162), void of an 'intrinsic, determinate structure' (Bell 1996, p. 596), capable of being ' "split up" into parts in different ways, none of which is intrinsically privileged over the others' (Levine 2002, p. 206), and 'intrinsically unstructured' (Kemmerling 2010, p. 166). What these conceptions deny is that all thoughts have a unique intrinsic structure as per Unique Analysis. For brevity, we will say that they regard thoughts as unstructured. The conception of thoughts as unstructured entities is motivated by the fact that Frege often identifies the thought expressed by pairs of sentences with different surface structure. For instance, Frege takes sentences like the following to express the same thought:2 (A1) A is heavier than B. (A2) B is lighter than A. It thus appears that the same thought can be decomposed in very different ways: (A1-D) <[A], [x is heavier than y], [B]> (A2-D) <[B], [x is lighter than y], [A]> The problem for a Dummettian conception of thoughts is now to provide a principled way of determining that the unique structure of the thought expressed by (A1) and (A2) 2In the Begriffsschrift Frege identifies the content of sentences of the form of (A1/A2), see 1879, §9. Later he identifies the thought expressed by sentences analogous to (A1/A2), see 1897, p. 141; 1892a, p. 188; 1918, p. 357. 6 is given by this rather than that decomposition. In contrast, a conception of thoughts as unstructured entities has no such problem. It will simply take the sentences to indicate different possible decompositions none of which has to be regarded as revealing the structure of the thought. Accordingly, a conception of thoughts as unstructured entities predicts that there are several, equally good routes to the grasp of a given thought. The present thought can be grasped by way of grasping the senses revealed by (A1-D) and it can equally be grasped by way of grasping the senses revealed by (A2-D). Both routes to the grasp of the thought are fine, neither is mandatory. Neither reveals a collection of senses which are such that the grasp of the thought must proceed via them. I propose to save Frege's theory from inconsistency by adopting the conception of thoughts as unstructured. Suppose Lauben utters (W1) I am wounded and Peter says to Lauben (W2) you are wounded. The present conception allows us to regard these two sentences as expressing one and the same unstructured thought which admits of the following distinct but equally good decompositions: (W1-D) <[ILauben], [x is wounded]> (W2-D) <[you], [x is wounded]> These decompositions constitute equally good routes to the grasp of the thought. Thus, the thought can be grasped via the sense [ILauben] which is private to Lauben. But it can equally be grasped via the public sense which Peter expresses with 'you' when addressing Lauben. Neither decomposition reveals a collection of senses such that the grasp of the thought must proceed via them and only them. Accordingly, the present account allows us to reject Contagious Privacy. The privacy of [ILauben] no longer transmits to the whole thought expressed by (W1) and (W2). It thereby enables us to countenance private senses without being committed to either private thoughts or to unthinkable thoughts. The account proposed can be seen as generalizing one of Frege's own insights. Frege states that '[t]he word "singular" does not apply to the thought in itself but only with respect to a particular way of splitting it up' (1906a, p. 202). According to my proposal, he should have said something similar about the word 'private'. Rather than pertaining to any thought itself, it should be seen as pertaining to some, but not all, decompositions of certain thoughts. 7 In virtue of this feature, the present account also offers a new way to make sense of the familiar idea that first person content plays a special role in cognition, in particular, in action explanation (see e.g. Perry 1979). It might appear that the only way to implement this insight within a Fregean setting is by postulating private thoughts (see Heck 2002, §2 for an account along those lines): what explains, say, Lauben's shouting for help is, among other things, his believing the private thought he would express with 'I was wounded'. The present account promises a way to preserve the privileged role of first person content without having to accept private or unthinkable thoughts. We can now allow that Peter grasps just the same thought as Lauben when he believes what he would express with 'you were wounded' (when addressing Lauben) without having to claim that healthy Peter is thereby equally motivated to shout for help. What accounts for the special role the thought plays in Lauben's cognitive life is not that he alone can grasp it, but that he alone can grasp it via the private decomposition (W1-D) containing the I-sense private to him.3 References Bell D. 1996. The formation of concepts and the structure of thoughts. Philosophy and Phenomenological Research 56: 583–596. Dummett M. 1981. The Interpretation of Frege's Philosophy. London: Duckworth. Evans G. 1981. Understanding demonstratives. In G. Evans, Collected Papers, 291–321. Oxford: Clarendon Press, 1985. Frege G. 1879. Conceptual Notation: A Formula Language of Pure Thought Modelled upon the Formula Language of Arithmetic. In T.W. Bynum, Conceptual Notation and Related Articles, 101–203, Oxford: Clarendon Press, 1972. ---. 1892a. On concept and object. In Frege 1984, pp. 182–194. ---. 1892b. On sense and meaning. In Frege 1984, pp. 157–177. ---. 1897. Logic. In Frege 1979, pp. 126–151. ---. 1906a. A brief survey of my logical doctrines. In Frege 1979, pp. 197–202. ---. 1906b. Introduction to logic. In Frege 1979, pp. 185–196. ---. 1915. My basic logical insights. In Frege 1979, pp. 251–252. 3I would like to thank TimButton, Lucy Campbell, FionaDoherty, Alexander Greenberg, OwenGriffiths, Richard Holton, Gerry Hough, Colin Johnston, Guy Longworth, Alex Oliver, Michael Potter, Shyane Siriwardena, Peter Sullivan, Mark Textor, Rob Trueman and Timothy Williamson for helpful comments and discussion. This work was presented at the 19th Annual Oxford Philosophy Graduate Conference, the Joint Sessions 2016 in Cardiff, and the Early Analytic Group in Stirling. 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