Philosophical Books Vol. 49 No. 4 © 2008 The Author. Journal compilation © 2008 Blackwell Publishing Ltd., 9600 Garsington Road, Oxford, OX4 2DQ, UK and 350 Main Street, Malden, MA 02148, USA Philosophical Books Vol. 49 No. 4 October 2008 pp. 344 –354 Blackwell Publishing LtdOxford, UKPHIBhil sophical Books0031-80511468 0149© Blackwell Publishers Ltd 2008XXXriginal Article RECENT WORK RESPONSE-DEPENDENCE DAVID YATES Institute of Philosophy, University of London Introduction Response-dependence is best conceived as a thesis concerning the properties of a particular domain-specifically, that they are anthropocentric dispositions. So conceived, a response-dependent property P is the property of having some other property that causes us to respond in a characteristic way to things that have it. This seems most plausible for secondary qualities, such as colours, tastes and smells, but the theory has been extended to cover qualities not traditionally construed as secondary, most notably moral values. Responsedependence allows for a 'qualified realism' about the properties in question- things really do have dispositions to cause responses in us, and these are not obviously less 'real' than the disposition of like charges to repel. But treating-say-moral values as response-dependent makes them dependent on us, in a way that offers a straightforward explanation of their existence. That response-dependence is a thesis about properties is obscured by the fact that most theorists formulate it in terms of concepts . It is important to bear in mind that the distinction thereby aimed at is typically ontological, not conceptual. Defining Response-Dependence The term 'response-dependent' was introduced by Mark Johnston, to denote concepts which "exhibit a conceptual dependence on or interdependence with concepts of our responses in certain specified conditions." 1 It is common in the literature to follow Crispin Wright in holding that this dependence is best understood by means of 'basic equations' of the form: For all S, P: P iff (if CS then RS) 1. M. Johnston, 'Dispositional Theories of Value', Proceedings of the Aristotelian Society Supp. Vol . 63 (1989), pp. 139–74, at p. 145. 345 © 2008 The Author. Journal compilation © 2008 Blackwell Publishing Ltd. where S, P range over subjects and propositions, respectively; 'CS' means 'S is in circumstances C', and RS means 'S is disposed to R'. 2 Consider the following applications of this schema: (1) x is square iff (if normal conditions obtain, then x is disposed to look square to normal subjects). (2) x is red iff (if normal conditions obtain, then x is disposed to look red to normal subjects). Suppose both are true. As Wright says, the intuitive 'order of determination' differs between (1) and (2). In (1), the judgements of normal subjects under normal conditions merely reflect the pre-determined extension of square ; in (2), by contrast, those judgements can be thought of as determining the extension of the concept red . The truth of biconditionals such as (1) and (2) is neutral between extension-determining and extension-reflecting roles for judgements. The central question of Plato's Euthyphro : are pious acts loved by the Gods because they are pious, or are they pious because they are loved by the Gods? Either way, it will be true that for any x , x is pious iff the Gods love x . A promising idea is that true basic equations that meet certain further conditions will pick out concepts for which, like red , the order of determination is 'rightto-left'. Specifying a list of sufficient conditions is no easy task. 3 I will consider two of the most popular necessary conditions: a prioricity and substantiality . Suppose we stipulate that response-dependent concepts are those that feature in a priori basic equations-while (2) is plausibly a priori, (1) is not. But this will not do, for we can make (1) a priori through a 'whatever-it-takes' account of normal conditions and subjects: (3) x is square iff (if conditions conducive to correctly judging shape by sight obtain, then x is disposed to look square to subjects capable of accurately identifying shapes by sight). The substantiality condition states that normalcy must not be specified in terms of issuing in the specified judgements, so avoiding trivial cases such as (3). Suppose we replace the trivializing account of normalcy in (3) with substantial specifications: (4) x is square iff (if x is well illuminated and in plain view, then x is disposed to look square to statistically normal subjects). While (4) may be true, it is clearly not a priori. Thus one test for response dependent concepts is: take a biconditional such as (3), and replace the trivializing conditions with substantial specifications of normal conditions 2. C. Wright, Truth and Objectivity (Harvard University Press, 1992), p. 108. 3. See appendix to Ch. 3 of Wright's Truth and Objectivity , 'The Euthyphro Contrast'; C. Wright, 'Moral Values, Projection and Secondary Qualities', Proceedings of the Aristotelian Society Supp. Vol. 62 (1988), pp. 1–26; M. Johnston, 'Objectivity Refigured: Pragmatism Without Verificationism', in J. Haldane & C. Wright (eds.) Reality, Representation and Projection , (Oxford University Press, 1992), esp. appendix 3, pp. 121–6. 346 © 2008 The Author. Journal compilation © 2008 Blackwell Publishing Ltd. and subjects. "[ I ]f the a priority of the biconditional survives substantial specification, then . . . we have the makings of a case for regarding best opinion as playing an extension-determining role." 4 Let us suppose for simplicity (and for now) that substantiality and a prioricity are necessary and sufficient for response-dependence. (5) x is F iff (if conditions C obtain, then S is disposed to R to x ). Is there a way of filling out C, S and R so that (5) comes out a priori? Not obviously- unless F = the concept of the disposition to produce R in S under C. Unless the analysans is part of the core beliefs that constitute F , then it is not at all clear how anyone could come to know anything like (5) a priori. 5 Johnston terms such concepts 'response-dispositional' and it is clear for the most part that he treats response-dependence and response-dispositionality as of a piece. 6 If F is response-dispositional, then the property (if any) expressed by F will be the disposition to produce R in S under C, and (5) will come out not only a priori, but also necessary. Setting up the issue in terms of responsedispositionality has several advantages. First, it enables us to explain the response-dependence of F -the a prioricity of (5)-in terms of the nature of the property expressed by F , so vindicating the ontological conception of response-dependence. 7 Second, it is in keeping with Locke's conception of secondary qualities as powers to produce sensory experiences in us. 8 And third, it gives clear sense to Wright's distinction between extension-determining and extension-reflecting judgements. However, there is a complication in the notion of a response-dispositional concept, that renders it inapplicable to some cases of response-dependence. This is that response-dependent analyses are often circular-in (2) above red occurs in both analysandum and analysans. This kind of circularity need not be vicious, for we can bring out interesting conceptual relations without thereby reducing any of the concepts involved to any of the others. 9 By way of contrast, consider: (6) x is good iff (if conditions C obtain, then S is disposed to approve of x ). 4. C. Wright, 'Realism: The Contemporary Debate-W(h)ither Now?', in J. Haldane & C. Wright (eds.), Reality, Representation and Projection , pp. 63–85, p. 78. 5. Similar points are made in N. Miscevic, 'The Aposteriority of Response-Dependence', The Monist , 81 (1998), pp. 69–84; M. Lebar, 'Two Dogmas of Response-Dependence', Philosophical Studies , 123 (2005), pp. 175–211. 6. See his 'Explanation, Response-Dependence and Judgement-Dependence', in P. Menzies (ed.), Response-Dependent Concepts (ANU RSSS, 1991), pp. 122–83, esp. pp. 141–50; and 'Are Manifest Qualities Response-Dependent?', The Monist , 81 (1998), pp. 3–43. 7. See R. Wedgwood, 'The Essence of Response-Dependence', European Review of Philosophy , 3 (1998), pp. 37–60 for a defence of the ontological conception of response-dependence without commitment to the view that response-dependent properties are dispositions. 8. See Johnston's 'How to Speak of the Colours', Philosophical Studies , 68 (1992), pp. 221–63, for a defence of a dispositionalist theory of colour. Johnston later rejects the theory, based in part on his own 'missing explanation argument'-of which more in part (4). 9. R. Keefe, 'When Does Circularity Matter?', Proceeding of the Aristotelian Society , 102 (2002), pp. 253–70. 347 © 2008 The Author. Journal compilation © 2008 Blackwell Publishing Ltd. (7) x is good iff (if conditions C obtain, then S is disposed to judge that x is good). (6) is reductive, and consistent with a response-dispositional analysis of good , i.e. the content identity: good = the concept of the disposition to cause approval in S in C. (7) is non-reductive, for good occurs in both analysans and analysandum. 10 The corresponding account of the a prioricity of (7) would be: good = the concept of the disposition to cause S in C to judge to be good. But this cannot be true, as good occurs on both sides of the identity sign. This in turn makes it very difficult to see how (7) could be a priori. Note that the a posteriority of (7) is consistent with the claim that the property of being good = the disposition to cause S in C to judge to be good. Many extant response-dependent analyses are circular, as in (7), and I think it likely that all such biconditionals will be a posteriori. But in that case, we might be better off not trying to characterize response-dependence by way of basic equations at all, for the purpose of those equations is precisely that a priori knowledge of them is, given other conditions, sufficient for response-dependence of the properties in the domain. Talk of 'response-dependent concepts' (concepts that feature in a priori basic equations meeting certain conditions) is typically a conceptual way of making an ontological distinction. Philip Pettit's theory of response-dependent concepts is an exception-response-dependence, for Pettit, is a feature of concepts, and carries no ontological import regarding the properties they express. 11 In outline, the theory is as follows. We learn concepts such as red by ostension, which in turn depends on our having primitive dispositions to react (by having certain sensations, for instance) in the presence of red things. Thus the first stage of conceptual competence is a disposition to apply the concept red when, and only when, things seem red. But we also have higher-order dispositions to withhold assent from our judgements in case of disagreements, and rule out the conditions under which such disagreements reliably arise as abnormal. Normal conditions can then be defined as those that are "fit to survive practices of resolving discrepancies." 12 Refer back to the basic equation for red, (2). Pettit claims that those "party to the way people follow their sensations and adjust in the face of discrepancies will be in a position to know the truth of the biconditional [a priori] . . .". I need not take issue with this claim. Abbreviate the 'Ethnocentric theory' 10. This is prima facie inconsistent with an extension-determining role for best judgement, for it seems that unless the extension of good is already determined, the judgement that x is good will have no determinate content, and so be unfit for its putative extension-determining role. See Wright's Truth and Objectivity , pp. 132–5 for discussion. 11. See P. Pettit, 'Realism and Response-Dependence', Mind , 100 (1991), pp. 587–626; P. Pettit, 'Terms, Things and Response-Dependence', European Review of Philosophy, 3 (1998), pp. 61– 72; F. Jackson and P. Pettit, 'Response-Dependence Without Tears', Philosophical Issues, 12 (2002), pp. 96–117. 12. Pettit, 'Terms, Things and Response-Dependence' p. 58. See also P. Pettit, 'A Theory of Normal and Ideal Conditions', Philosophical Studies, 96 (1999), pp. 21–44. See J. Haukioja, 'How (Not) to Specify Normal Conditions for Response-Dependent Concepts', Australasian Journal of Philosophy, 85 (2007), pp. 325–31, for arguments that Pettit's theory of normal conditions is the only one consistent with the a prioricity of basic equations. 348 © 2008 The Author. Journal compilation © 2008 Blackwell Publishing Ltd. outlined above by 'E'. What is knowable a priori, on Pettit's account, is something like this: (8) E implies {if red expresses a property then [x is red iff (if normal conditions obtain, then x is disposed to look red to normal subjects)]}. The a prioricity of (8) lends no support to the view that the property of being red is response-dependent. If (8) is a priori, it is so in virtue of concept possession conditions, not the nature of the properties they express. Pettit is quite clear that for all his theory tells us, red might express the responsedependent disposition to cause red sensations in us, or the actual world realizers of that disposition.13 Pettit's theory is of considerable interest-it promises, for instance, to provide a non-sceptical solution to at least some of Kripkenstein's rule-following considerations.14 But it is not response-dependence in the traditional sense of the term; further discussion is therefore beyond the scope of this paper. Applications of Response-Dependence Response-dependence permits a qualified realism about a domain of properties. The advantages of this kind of realism are perhaps clearest in the case of moral values.15 What are morals, and where did they come from? How do we get to know about them? Response-dependence promises to solve both the ontological and epistemological worries at the same time. Morals are anthropocentric dispositions to cause certain responses in us, and these dispositions are revealed to us in their manifestations. Attributions of moral value, on this approach, are truth evaluable; more than that, they are sometimes true. Further, response-dependence about moral values promises to respect 'motivational internalism'-the view that moral judgements are necessarily connected to motivational states such as desires-without resorting to noncognitivism. Non-cognitivists argue that moral judgements cannot express beliefs, for moral judgements are necessarily connected to desires, whereas beliefs and desires are distinct existences.16 But now suppose we build desire into the response that defines the property of being good, as does David Lewis.17 The judgement that x is good does express a belief, but it is a belief 13. See his 'Noumenalism and Response-Dependence', The Monist, 81 (1998) pp. 112–32. 14. S. Kripke, Wittgenstein on Rules and Private Language (Harvard University Press, 1982); see F. Hindricks, 'A Modest Solution to the Problem of Rule-Following', Philosophical Studies, 121 (2004), pp. 65–98, for discussion of Pettit's solution to the problems Kripke raises. 15. A good place to start is M. Smith, D. Lewis and M. Johnston, 'Dispositional Theories of Value', Proceedings of the Aristotelian Society Supp. Vol. 63 (1989), pp. 89–174. 16. See M. Smith, 'Response-Dependence Without Reduction', European Review of Philosophy, 3 (1998), pp. 85–108. 17. D. Lewis, 'Dispositional Theories of Value', p. 116. See also T. Cuneo, 'Are Moral Qualities Response-Dependent?', Noûs, 35 (2001), pp. 569–91, esp. pp. 572–3; and part (1) of B. Thompson, 'Moral Value, Response-Dependence and Rigid Designation', Canadian Journal of Philosophy, 36 (2006), pp. 71–94. 349 © 2008 The Author. Journal compilation © 2008 Blackwell Publishing Ltd. about (inter alia) the disposition of x to elicit desire in normal individuals under normal conditions. More generally, response-dependence preserves what is good about pragmatism-for instance the anti-transcendentalist thought that (for instance) the moral truths cannot outrun the limits of our cognitive abilities-without endorsing anything like the verificationist theory of truth typically associated with pragmatism.18 The domain specificity of responsedependence means that the issue of whether the truth-conditions of statements of a particular domain are determined by best opinion is independent of the issue whether truth itself is so determined. The problems associated with response-dependent approaches are also domain-specific. Although (7), for instance, is conceptually circular ( good occurs in both analysans and analysandum) it is not ontologically circular. The occurrence of good in the analysans is within the intensional context 'judges that' and so serves to pick out a psychological property. This is why the conceptual circularity of (7) is consistent with the view that the property of being good is the disposition to cause the psychological property in question. In some cases, however, there is a deeper circularity. Consider this response-dependent form of interpretivism:19 (9) x believes that p iff (if conditions C obtain, then S is disposed to attribute to x the belief that p). As Alex Byrne points out, the analysis is not merely conceptually circular and non-reductive; it is also ontologically circular in that the analysans presupposes facts about the psychological contents of interpreters.20 Even if (9) is a priori and necessary under some non-trivial specifications of S and C (which is in itself doubtful), it is doubtful that we can treat interpreters' best judgements as determining, rather than merely tracking, psychological truths.21 In the remainder of this section, I will consider the application of response-dependence to colours and moral values. Let the term 'red ' rigidly designate states with the same phenomenal character as the visual experiences we have when we look at ripe tomatoes.22 Then the following is a prima facie plausible reductive analysis of red, very close to Locke's: (10) x is red iff (if normal conditions obtain, then x is disposed to cause red  sensations in normal observers). 18. See M. Johnston, 'Objectivity Refigured'; A. Howat, 'Pragmatism, Truth and ResponseDependence', Facta Philosophica, 7 (2005), pp. 231–53; C. Norris, 'Ambiguities of the Third Way: Realism, Anti-Realism and Response-Dependence', The Philosophical Forum, 33 (2002), pp. 1–38. 19. See A. Byrne, 'Interpretivism', European Review of Philosophy, 3 (1998), pp. 199–223. 20. Byrne, 'Interpretivism', pp. 205–6. 21. Similar concerns trouble response-dependent accounts of causation. See P. Menzies and H. Price, 'Causation as a Secondary Quality', British Journal for the Philosophy of Science, 44 (1993), pp. 187–203. 22. This idea comes from C. Peacocke, Sense and Content (Oxford University Press, 1983). 350 © 2008 The Author. Journal compilation © 2008 Blackwell Publishing Ltd. An immediate worry with this kind of formulation is that it implies that if normal subjects undergo surgical red-green spectrum inversion, such that things which cause red′ sensations today cause green′ sensations tomorrow (and vice versa), then tomorrow, grass will be red and post boxes green, despite no intrinsic change in either. Many share the intuition that this is the wrong way to describe the change. The proper way is to say that tomorrow red things will look green and green things will look red, but (10) does not allow for this. I do not share this intuition about the colours; about moral values I am less sure. (11) x is good iff (if normal conditions obtain, then x is disposed to cause moral approbation in normal observers). What should we say if, overnight, cruelty to animals becomes such as to elicit moral approbation? As Simon Blackburn puts it, "if everyone comes to think of it as permissible to maltreat animals, that does nothing at all to make it permissible: it just means that everyone has deteriorated".23 Intuitively, no stable disposition towards cruelty, in any circumstances, on the part of any subjects, would suffice to make cruelty good. But (11) implies that the extension of good will change if the subjects' dispositions change. The standard way of dealing with such objections is to introduce a rigidifying operator, 'actually'.24 Here is a rigidified biconditional for red: (12) x is red iff (if actual normal conditions obtain, then x is disposed to cause red′ sensations in actual normal observers) Since we are supposing that 'red ' rigidly designates a state with a specific phenomenal character, the responses are already rigidified. The addition of actuality operators rigidifies on the subjects and conditions as well. Our surgically altered humans are not actual, and so by (12) it is not their judgements that determine the extension of red. After the surgery, red things stay red but appear green. A particularly lively area of current debate concerns the question whether we ought to rigidify on the subjects in (11). Peter Railton argues against rigidification on the grounds that it prevents us making sense of certain kinds of moral change.25 Suppose that humans eventually come to reproduce through cloning, and as a result no longer attach moral significance to biological kinship. Ed is cloned from Ethan, and raised apart from him, as is common in the imagined future. Neither Ed nor Ethan knows that they are kin, and one day they come to be sharing a taxi 23. S. Blackburn, 'Errors and the Phenomenology of Value', in T. Honderich (ed.), Morality and Objectivity: A Tribute to J. L. Mackie (Routledge and Kegan Paul, 1985), p. 14. See also Wright, 'Moral Values, Projection and Secondary Qualities', pp. 8–11; Lewis, 'Dispositional Theories of Value', p. 132. 24. The idea of rigidification is due to M. Davies and L. Humberstone, 'Two Notions of Necessity', Philosophical Studies, 38 (1980), pp. 1–30. 25. P. Railton, 'Red, Bitter, Good' European Review of Philosophy, 3 (1998), pp. 67–84. The account I give is greatly simplified; for detailed discussion of Railton's arguments see Thompson's 'Moral Value, Response-Dependence and Rigid Designation'. 351 © 2008 The Author. Journal compilation © 2008 Blackwell Publishing Ltd. with a third person, Bill. We can suppose that Ed would gain greater fulfilment from a conversation with Bill than one with Ethan. Is it better for Ed to talk to Bill, or Ethan? Railton seems to expect us to feel a certain moral approbation towards Ed's talking to Ethan-in that case, according to a rigidified (11), we should say that it is morally better if Ed talks to Ethan. We must describe future humans' lack of our actual dispositions towards kinship in terms of their having become desensitized to its value. But he also wants us to agree that from Ed's point of view, it would be better if he spoke to Bill. The admission that what is morally good for us may not be good for others is inconsistent with rigidified response-dependence about moral values. Railton argues that the semantics of good is closer to that of secondary quality concepts like bitter and sweet than it is to red. Just as we are happy to acknowledge that what is bitter for one may be sweet for another, so in the moral case we are prepared to treat certain properties such as kinship as having moral significance for one group of individuals, and not for others. The proper treatment of good has the general form: (13) x is good-for-P iff (if normal conditions obtain, then x is disposed to cause moral approbation in normal members of population P). According to (13), cruelty to animals comes out good for any population whose normal members are disposed to approve it. In addition, changes in the dispositions of a given population P towards some x would change whether x is good for P. Sean Holland takes such consequences to be unacceptable, but goes on to argue that rigidified accounts do not work either, hence that the dispositional theory of value is false.26 Here, slightly altered, is how the argument goes. Suppose that on Earth, we judge actions good only if they are performed out of duty, whereas on TwinEarth, actions are judged good only if they have good consequences. Rigid response-dependence implies that on Earth, good rigidly designates the disposition to cause moral approbation in us, whereas on Twin-Earth (considered as actual) goodTE rigidly designates the disposition to cause moral approbation in them. Due to the differences in our affective dispositions, good and goodTE are extensionally non-equivalent. Since each is by hypothesis rigid, it follows that they cannot have the same content. But this makes moral disagreements between ourselves and Twin-Earthlings merely apparent, for we do not have a common language in which to disagree. Intuitively, however, the disagreement between ourselves and the Twin-Earthlings ought to be the same as the disagreement between consequentialists and deontologists on Earth. A promising reply to Holland's argument, due to Mark Lebar, proceeds roughly as follows.27 Suppose supervenience of the moral on the non-moral. Then there must be a non-moral difference between Earth and Twin-Earth-following Lebar, let us understand this to be a difference in 'psychological temperament'. Either this difference justifies the difference in judgements across worlds, or it does 26. S. Holland, 'Dispositional Theories of Value Meet Moral Twin Earth', American Philosophical Quarterly 38 (2001), pp. 177–95. 27. 'Two Dogmas of Response-Dependence', pp. 193–6. 352 © 2008 The Author. Journal compilation © 2008 Blackwell Publishing Ltd. not. If our Twins' judgements are not rationally justified then we do not need to worry about the fact that their judgements are different from our own. But if we take them to be justified, then we admit the possibility that others with different psychological temperaments could have good rational grounds for approving different classes of actions from ourselves, in which case it is chauvinistic to insist that moral values be rigidified on our dispositions. Perhaps, as Lebar claims, the source of these difficulties is the application of intuitions dependent on our actual responses to counterfactual situations such as moral Twin-Earth where, by hypothesis, people respond differently. The 'Missing Explanation' Argument Mark Johnston's 'missing explanation' argument is primarily designed to show that no basic equation featuring our everyday concepts of manifest qualities such as colours is both a priori and necessary.28 Since response-dispositional concepts do yield a priori and necessary basic equations, the argument would also show that our concepts are not response-dispositional. This would not, in turn, show that colours are not dispositional properties;29 I shall return to this issue presently. The argument depends on the following substitution principle: [Sub]:Where S′ and S* are equivalent as an a priori and necessary matter, if 'S because S′' states a true empirical explanation then 'S because S*' is not an explanatory solecism.30 Here an 'explanatory solecism' is a statement of the form 'x because y' that is a priori false. Following Alexander Miller, I will consider the following response-dependent account of red:31 (14) It is a priori and necessary that (x is red iff x is disposed to look red to normal observers in normal conditions). Our ordinary concept red is such that: (15) For some x, x is disposed to look red to normal observers in normal conditions because x is red. Red is the concept of a sensible quality, and the truth of explanations of this form is a necessary condition on sensibility.32 But substituting for 'x is red' in (15) we get: 28. For a detailed presentation of this argument, see Johnston's 'Explanation, Response-Dependence and Judgement-Dependence'; and 'Are Manifest Qualities Response-Dependent?'. 29. Hence Johnston's revisionary strategy in 'Objectivity Refigured: Pragmatism Without Verificationism'-our ordinary concepts are not response-dispositional, but ought in some cases to be recast as such to exhibit the dispositional nature of the properties they express. 30. 'Explanation, Response-Dependence and Judgement-Dependence', p. 130. 31. A. Miller, 'The Missing Explanation Argument Revisited', Analysis, 61 (2001), pp. 76–86. 32. See Johnston's 'Explanation, Response-Dependence and Judgement-Dependence'. 353 © 2008 The Author. Journal compilation © 2008 Blackwell Publishing Ltd. (16) For some x, x is disposed to look red to normal observers in normal conditions because x is disposed to look red to normal observers in normal conditions. Since (16) is an explanatory solecism, either (15) is false, or (14) is false. It is part of our ordinary concept red that it is a property we sense, and this requires the truth of (15), so (14) is false. But if red = the concept of the disposition to look red to normal observers in normal conditions, then (14) is true. Thus, red is not a response-dispositional concept; neither is any of our other ordinary concepts of sensible qualities. The argument leaves it open that basic equations for red are a posteriori necessary, and so that the property of being red = the disposition to look red to normal observers in normal conditions. Miller replies by questioning [Sub]-response-dependence biconditionals are not supposed to be reductive content identities, and only if they are treated as such does [Sub] seem plausible.33 I do not think this argument is to the point. Response-dependence can be non-reductive, but as I argued in part (2), non-reductive basic equations plausibly cannot be a priori. If I am right that the response-dispositionality of red is necessary (as well as, uncontroversially, sufficient) for the truth of (14), then the embedded biconditional in (14) does provide the content identities needed to make the substitution principle intuitive. What the missing explanation argument shows is that our ordinary concepts of sensible qualities are not response-dispositional, and so-if I am correct-that basic equations featuring those concepts are not a priori. Peter Menzies and Phillip Pettit accept [Sub], but argue that it does not apply, since the sentence 'x is disposed to look red to normal observers in normal conditions' expresses different propositions in (14) and (15).34 The question 'why is x disposed to look red to normal observers in normal conditions?', they argue, is ambiguous between a possession reading and a manifestation reading. First question: why does the object possess that disposition rather than any other; what is the ground of the disposition in the object? Second question: why, in appropriate circumstances, does the thing look red; what is the trigger that activates the disposition and accounts for the appearance of redness?35 (14) requires a possession reading, but considerations of the necessary conditions on sensibility only motivate a manifestation reading of (15), whose truth is consistent with (14), since substitution in the manifestation reading yields (17) For some x, x looks red to normal observers in normal conditions because x is disposed to look red to normal observers in normal conditions, 33. A. Miller, 'Objectivity Disfigured: Mark Johnston's Missing Explanation Argument', Philosophy and Phenomenological Research, 55 (1995), pp. 857–68; see also Howat 'Pragmatism, Truth and Response-Dependence'. 34. P. Menzies and P. Pettit, 'Found: The Missing Explanation', Analysis, 53 (1993), pp. 100–9. 35. 'Found: The Missing Explanation' pp. 104–5. 354 © 2008 The Author. Journal compilation © 2008 Blackwell Publishing Ltd. which is not a solecism. Johnston spends much of his 'Are Manifest Qualities Response-Dependent?' arguing, in reply to Menzies and Pettit, for the stronger, possession reading of (15) as a necessary condition on sensibility.36 I leave it to the reader to decide whether his arguments are successful. Note, however, that Johnston only needs such an argument because he accepts that dispositions explain their manifestations. We can accept that (17) is not a solecism, but this does not mean that it is true, or even (metaphysically) possible. Given that (17) is a putative condition on the sensibility of redness, 'because' must be read as causal. Do dispositions cause their manifestations? If the connection between possessing a disposition in the triggering circumstances, and its manifestation, is metaphysically necessary, then (given Hume's principle that cause and effect must be distinct existences) it would appear not.37 Robert Pargetter holds that dispositions are not causes, and appeals to their inefficacy to show that moral properties cannot be both apprehensible by our senses and response-dependent.38 Here, then, are the makings of a serious problem for response-dependence. What is essential to response-dependence about a domain of properties, I have urged, is that the properties in the domain are identified with anthropocentric dispositions. But if dispositions are not efficacious, then it seems response-dependent properties are qualities we project onto, rather than detect in, the world. 'Qualified realism', so understood, is no realism at all.39 36. See Miller, 'The Missing Explanation Argument Revisited', for argument that the possession reading of (15) is not necessary for sensibility, and that we can make do with weaker conditions such as (17). 37. See J. McKitrick, 'Are Dispositions Causally Relevant?', Synthese, 144 (2005), pp. 357–71, for discussion of this and other arguments against the causal relevance of dispositions. 38. R. Pargetter, 'Goodness and Redness', Philosophical Papers, 17 (1988), pp. 113–26. Related arguments against the physicality of response-dependent properties are to be found in M. Powell, 'Realism or Response-Dependence', European Review of Philosophy, 3 (1998), pp. 1–13; and C. Wright, 'Euthyphronism and the Physicality of Colour', European Review of Philosophy, 3 (1998), pp. 15–30. 39. Thanks to Andrew Howat, Cecilia Texeira and Barry Smith for their assistance in the preparation of this paper, which was completed while in receipt of a British Academy Postdoctoral Fellowship.