LOCKE'S CRITERION FOR THE REALITY OF IDEAS: UNAMBIGUOUS BUT UNTENABLE CORNELIS DE WAAL When his. Essay concerning human understanding is nearly finished, Locke suddenly comes to realize that his doctrine of ideas leaves him with no means to distinguish reality from fiction. Given his view of knowledge as 'the perception of the connexion and agreement, or disagreement and repugnancy of any of our Ideas' (IV. i. 2), he is forced to admit that 'the Visions of an Enthusiast, and the Reasonings of a sober Man, will be equally certain' (IV. iv. 1).1 To make matters worse, it is the enthusiast who would be the most knowledgeable, not only because he has more ideas, but also because they are the more lively (ibid.). 'Idea' here stands for whatsoever is 'the immediate object of Perception, Thought, or Understanding' (II. viii. 8; cf. I. i. 8). In this paper I examine Locke's reaction to this problem, and argue against the charge, made by several commentators, that Locke commits himself to a double standard when determining whether an object we think of is real. As I will show, this charge results from a confusion of Locke's criterion of reality with its application. For Locke, there is only one criterion upon which something we think of is real, namely, when it conforms with its archetype. It is only when this criterion is applied to the different types of ideas that Locke distinguishes, that it works out differently. To support this reading I will, like Locke, rewrite the issue in terms of an archetype-ectype relationship and apply this to the three types of ideas Locke distinguishes. I John Locke, An essay concerning human understanding, ed. P. H. Nidditch (Oxford 1975). All references to this work are by book, chapter, and section number. 29 •' I I I i'. :j !: ! The Locke Newsletter / Locke Studies 28 (1997): 1–22. Although this will prove that Locke indeed holds a single criterion for the reality of ideas, the result is not all that favourable for Locke. Part of what motivates Locke in his search for a criterion for the reality of ideas, is trying to avoid concluding that all products of our thought-including the ideas of mathematics and moral reasoning-must be dismissed as fiction. Unfortunately, on the criterion introduced by Locke, the exact opposite occurs. This time far too much must be designated as real, which leaves hardly any room for anything to be a fiction, that is, for anything to be not real. This means that Locke's criterion for the reality of ideas fails on his own terms, that is, he is still unable to distinguish the reasonings of the sober man from the visions of the enthusiast. I As noted, Locke comes to realize that his 'way of ideas' leaves him without the means to distinguish reality from fiction. He reacts to this problem by holding that what we think of is real, as opposed to a product of our imagination, when there is, as he puts it, 'a conformity between our Ideas and the reality of Things' (IV. iv. 3). Given his belief that the understanding is entirely passive in experience (II. i. 25), the paradigmatic case in which the objects of our understanding are real is when they conform to things external to our understanding.2 This is 2 Although Locke seems to reserve the rerm 'external' strictly for the objects of sensation, it seems to me that the objects of reflection are, on Locke's terms, also external. Just like the objects of sensation, the objects of reflection too are received passively, namely, as simple ideas (II. vi). Because of this, the objects of reflection can become objects of the understanding only as ideas. This makes the faculties of the mind as external to the understanding as the objects of sensation. Admittedly, when discussing reflection, Locke writes: 'This Source of Ideas, every Man has wholly in himself: And though it be not Sense, as having nothing to do with external Objects; yet it is very like it, and might properly enough be call'd internal Sense' (II. i. 4; 30 because, if the understanding is indeed passive in experience, what it experiences cannot be a product of the understanding, and so cannot be a fiction of our fancy. Although Locke sees this as a clear case in which what we think of is real, he denies that this must be taken to imply that only ideas that conform to what is external to the understanding are real. This is especially clear from the way in which he raises the issue at the end of Book II, where he seems to present two independent criteria for determining whether something we think of is real-as opposed to a product of our fancy-one of which does not refer to an external reality at all.3 * second emphasis added). In this passage Locke clearly seems to deny that the operations of the mind are external. It is as if he is saying that although what we perceive in reflection is very much like perceiving external objects, the objects of reflection are not really external. But at the same time he treats the mind, or the soul, in much the same way as he treats external objects, that is as a something-we-know-not-what, or substratum, which is the bearer of the qualities we perceive. As Locke explains: 'the Operations of the Mind . . . which we concluding not to subsist of themselves, nor apprehending how they can belong to Body, or be produced by it, we are apt to think these the Actions of some other Substance, which we call Spirit' (II. xx.iii. 5; cf. 1533). This is further confirmed by Locke's theory of the self. J The two chapters of Book II that deal with Locke's conception of reality are xxx and xxxi. These two chapters are late additions to Book II, as can be seen from earlier drafts of the Essay. The main body of Book II is already present in what is called draft B, with the exception of the last five chapters, including chapters xxx and xxxi. Draft B, which was written in 1671, covers only what was to become the first two books of the Essay. The next major draft of the Essay that survives is draft C, dated 1685; which is four years before the Essay was printed. During the fourteen years between Draft B and Draft C, Locke works intermittently on problems that emerge from his original thesis, resulting in Books III and IV. In draft C moreover, Locke puts his signature directly after chapter II. xxviii, suggesting that Book II was supposed to end there. Later Locke added two additional chapters to this draft. The first deals with clear and distinct ideas, and corresponds closely to II. xxix; the second, called 'Of Real and Fantastical, Adequate and Inadequate Ideas', corresponds roughly to what is now II. xxx and xxxi. This suggests that Locke's discussion of the reality of ideas is a late addition to the Essay. See P. H. Nidditch and G. A. J. Rogers (eds), Drafts for the Essay concerning human understanding, and other philosophical writings (Oxford 1990). 31 There he writes that: By real Ideas, I mean such as have a Foundation in Nature; such as have a Conformity with the real Being, and Existence of Things, or with their Archetypes. Fantastical or Chimerical, I call such as have no Foundation in Nature, nor have any Conformity with that reality of Being to which they are tacitly referr'd, as to their Archetypes. (II. xxx. 1)4 According to this passage, what we think of is real, first, when it conforms with what Locke calls the 'real Being, and Existence of Things', or, second, when it conforms with its own archetype, irre~pective of whether this conforms with the real being and existence of things.s Locke's prime motive for calling 4 This passage is both obscure and confusing. First, it is asymmetrical. In his definition of real ideas, Locke distinguishes two ways in which ideas can be real: first, by having a conformity with the 'real Being, and Existence of Things', and, second, by having a conformity with their archetype. This seems to imply that conforming with their archetype is one way in which ideas can have 'a real Foundation in Nature'. In the next sentence, however, where he defines fantastical ideas, Locke seems to deny this. There he writes that ideas are fantastical when they have no foundation in nature, nor a conformity with their archetypes; thus setting conforming with their archetype apart from having a foundation in nature. Instead, Locke speaks of a 'Conformity with that reality of Being to which they are tacitly referr'd, as to their Archetypes' (II. xxx. I, emphasis added). The distinction between real and fantastical ideas is further obscured by the fact that the term 'real' or 'reality' surfaces three times in the passage cited, and nowhere in the Essay is there a clear account of what the term means. It is painfully absent in Book II, which is meant to show how all important concepts can be the result of experience. To make things worse, each time the term is used in the above passage, it means something entirely different. It refers, first, to 'the real Being, and Existence of Things'; second, to ideas that conform with this real being, and existence of things; and, third, to ideas that conform with 'that reality of Being to which they are tacitly referr'd, as to their Archetypes', where this 'reality of Being' is explicitly distinguished from 'the real Being, and Existence of Things' and of which it is not clear whether it has a foundation in naturi: or not. 5 There seem to be several ways to interpret Locke's text. One could hold, for instance, that the phrases 'the reality of Things' and 'the real Being, and Existence of Things' are synonymous, which commits one to saying that Locke's view changed between IV. iv. 3 and 11. xxx. 1. One could hold alternatively that Locke's view is the same in both passages, which commits one to saying that the two phrases are not synonymous, for instance by holding that the latter denotes only a subclass of the 32 the latter real too, is to save mathematics and moral reasoning from being dismissed as mere products of our imagination. With respect to the first, he argues, 'it will be easily granted that the Knowledge we may have of Mathematical Truths, is not only certain, but real Knowledge; and not the bare empty Vision of vain, insignificant Chimeras of the Brain' (IV. iv. 6). Moral reasoning, in turn, is not at all intended to express how things are, btit is meant instead to express how they should be. For Locke, the question whether things are as they should be has no bearing on the claim that they should be. Tully's Offices, Locke notes, are not any less true when nobody in the world exactly practises his rules (IV. iv. 8). Making the reality of our ideas depend solely on a conformity with the real being and existence of things will* thus fail to do justice to important segments of our knowledge, and therefore cannot be maintained. Locke's more refined view, however, quickly led to the charge that he employs a double standard, arbitrarily switching from one to the other when it suits him better. This charge is prominent, for instance, in Leibniz's commentary on the Essay, in which he complains: You give one account of the real/chimerical distinction for ideas of modes, and a different one for ideas of substantial things: you have two distinctions, with nothing in common between them that I can see. 6 More recently, this interpretation of Locke's conception of reality has been defended by James Gibson, 1 and, with the additional charge that Locke uses this double standard incoherently, former. This second interpretation is taken in this paper. One can also hold, of course, that Locke's view changed and that the phrases are not identical. 6 Leibniz, New essays on human understanding, tr. Pi Remnant & 1. Bennett (Cambridge 1970), bk II, ch. xxx, sec. S; emphasis added. 7 Locke's theory of knowledge (Cambridge 1917), pp. 132f. 33 *. by R. S. Woolhouse.s Others, however, like Martha Bolton9 and Paul Helm,10 defend Locke against the Leibnizian charge. Although I agree with Bolton and Helm that Locke does indeed hold a single criterion for the reality of ideas, I do not agree with their respective accounts of what this criterion is. Bolton paraphrases the passage from II. xxx. 1 quoted above as follows: 'an idea is real if it represents some real thing which it is supposed to represent and fantastical if it does not' .11 Depending on whether we can form ourselves an idea of this 'real thing', this account turns out to be either circular or incomprehensible. In the case in which we can form ourselves an idea of this 'real thing', Bolton's account will be circular, since it would define real ideas in terms of real ideas. In the case in which we cannot form ourselves an idea of these 'real things', Bolton's account will be incomprehensible, since real ideas would then be defined in terms of something we cannot get an idea of. Helm attributes to Locke a different criterion for the reality of ideas. In his view 'consistency is both necessary and sufficient for the reality of ideas both of mixed modes and substances'.12 Although I think Helm is correct in his assessment that, for Locke, consistency is both a necessary and a sufficient criterion for the reality of mixed modes, I disagree with his claim that 8 'Locke, Leibniz, and the reality of ideas', in R. Brandt (ed.), John Locke: Symposium Woljc•nbuttel 1979 (Berlin 1981 ), p. 196. See also his 'Helm, and Locke on real ideas', The Locke newsletter 14 (1983), pp. 35-9. 9 'Substances, substrata, and names of essences in Locke's Essay', Philosophical review 85 (1976), pp. 488-513. 10 Review of John Locke: Symposium Wolfenbuttel 1979, in The Locke newsletter 13 (1982), pp. 71-81, esp. pp. 76ff. See also his 'Locke's real ideas, and Dr Woolhouse', *The Locke newsletter I 5 (1984), pp. 35-42. 11 Op. cit., p. 496. 12 Op. cit., p. 77. 34 Locke regards consistency as also a sufficient condition for the reality of substances. Helm, moreover, does not discuss Locke's views on the reality of simple ideas, to which his criterion does not properly apply. II r. Perhaps the strongest sign that there is a single principle behind ~ the two criteria given by Locke in II. xxx. 1 is that he rewrites ;, both in terms of an archetype-ectype relation. An archetype (expxi7u7rov), in this context, is an original pattern or form, to which later things may correspond; an ectype (eKru7rov), in contrast, is an imprint or copy of an archetype.13 Thus whereas the archetype acts as a signet, able to make impressions upon other things, the ectype is an impression made by such a signet. To say that ideas are real because they conform with the real being and existence of things, then, is to say that they are imprints, impressions, or reproductions of the things themselves they intend to represent. With our idea of gold, for instance, Locke argues, we intend to represent something existing without the mind, of which our conception is only a rough or inaccurate imprint. This means that ideas which are intended to represent the real being and existence of things, will be real when they are ectypes of this real being and existence of things (cf. II. xxxi. 13), the latter acting as their archetypes. This, however, is not the only way in which an idea can conform with its archetype. The archetype of an idea need not be something other than an idea; it can also be another idea, or 13 Although Locke uses the terms *ectype' and 'archetype', he does not give an account of what the terms stand for. This leaves us largely with an etymological reconstruction; especially since even the Oxford English Dictionary quotes from the Essay as a paradigmatic example of their use. 35 ~ I even the idea itself. Someone can construct by a free act of the understanding, say, the idea of adultery, irrespective of whether adultery has ever been committed, or ever will be. In this case the idea is itself the archetype, in that it is from then on the idea that determines what something must be lih for it to conform with that idea (IV. iv. 8). Here the situation is exactly the reverse of the previous one. Now the ideas are the archetypes of which real existences, in so far as they conform with these ideas, will be ectypes. Hence, what is at issue here is not that there are two different conceptions of reality which have, as Leibniz puts it, 'nothing in common between them', but that there are different types of ideas-as Locke explicitly acknowledges throughout his Essayfor which the issue of their reality works out differently. In order to support this claim further, and to get a better idea of what exactly it amounts to, on Locke's terms, to say that an object of our thought is real, I will, as Locke does himself, ask, for each of the three types of ideas he distinguishes, when they are real as opposed to a product of our imagination. This then will provide us with the material upon which to assess Locke's conception of reality. III According to Locke, our ideas can be divided into three classes, which may be called simple ideas, substance ideas, and mode ideas. Although Locke presents several classifications of ideas, this one agrees best with our purpose, because it is these three types of ideas which Locke discusses with respect to their reality (see II. xxx. 2ff., and IV. xi. 13). The term 'mode idea' encompasses Locke's complex ideas of modes, his complex ideas of relations, his general ideas, and his 36 ideas of relation (the latter two are added only in the fourth edition of the Essay). Bringing the first two together under the heading 'mode ideas' is justified by the fact that Locke himself in his discussion of the reality of ideas limits himself to a subclass of only one of these groups, namely, mixed modes, and states afterwards that there is no significant difference between complex ideas of modes and complex ideas of relations regarding their reality (see II. xxx. 4 and xxxi. 14). The last two classes of ideas, which are added only in the fourth edition, Locke does not discuss at all with respect to their reality. In fact Book II is not at all updated for Locke's new division. The term 'substance idea' stands for Locke's complex ideas of substance. This latter more elaborate phrase is often abbreviated by Locke to a mere 'substance', a term he also uses with other meanings. Though the term most frequently denotes a complex idea of substance, it occasionally stands for real essence (II. xxxi. 13) or for substratum (II. xxiii. 1, III. iii. 9), neither of which are ideas at all. I will begin with the question under what conditions simple ideas will be real, since, for Locke, mode and substance ideas are both combinations of simple ideas (II. xii. 1). According to Locke, there is no doubt that we have such simple ideas. Nothing can be plainer to a man, he claims, 'than the clear and distinct Perception he has of those simple Ideas' (II. ii. 1). For the sake of argument I will assume not only that Locke is right in claiming that we have such simple ideas, but also in claiming that the understanding is entirely passive with respect to. their reception, and that all our ideas are either simple ideas or combinations of them. Based on the criterion given above, simple ideas will be real when they conform with their archetype. There are two ways, Locke claims, in which an object of our thought can conform with its archetype: by being an ectype of something else (as the seal is to the signet ring), or by being itself the archetype (II. 37 xxx. 4; cf. II. *~. 3). This latter, more peculiar use of the twoplace predicate '_ conforms with _' is somehow analogous to the more familiar use of the predicate '_ is identical with _' to express numerical identity. That an idea can conform with itself is confirmed by Locke's semiotic 'account of ideas at the end of book IV. Ideas are signs (IV. xxi. 4; cf. III. iii. 11; IV. v. 2), in which capacity they can refer either to something else or to themselves. Because the two ways of being real mentioned here are not mutually exclusive-since something can conform both with the real being and existence of things, and with itself-ideas can be real on both counts at the same time. I will therefore discuss both criteria for each type of ideas. As it turns out, simple ideas will be real on both counts, substance ideas will be real only on the first count, and mode ideas will be real only on the second count (seefig. 1). Fig.1: THE REALITY OF IDEAS simple idea substance idea mode idea Conforms with the real being and existence of things yes yes no Conforms with itself yes no yes According to Locke, the archetypes of simple ideas lie without the understanding. They are, as he puts it, the 'natural and regular productions of Things without us, really operating 38 upon us' and not 'fictions of our Fancies' (IV. iv. 4). This follows directly from Locke's view that all simple ideas are passively received by the understanding and must therefore have . an external origin (II. xxx. 2; cf. II. xii. 1; i. 6, 25; ii. 2). Because of this passivity of the understanding, Locke argues, simple ideas cannot but conform with their external causes, since it is from them that they derive their whole being. With this Loc~e does not intend to imply that all simple ideas are images or exact resemblances of what causes them. Correspondence, for Locke, does not entail resemblance, as the case of secondary qualities shows. For simple ideas to correspond to the reality of things, Locke argues, it suffices that they are the 'constant Effects' of what causes them (II. xxx. 2). In sum, simple ideas are real in the first sense; that is, they are ectypes of the real being and existence of things. In order to determine whether simple ideas also correspond to themselves, Locke introduces a second distinction pertaining ~to ideas in their capacity of representation: all ideas are either ~ adequate or inadequate. Ideas are adequate when they 'perfectly ~ represent those Archetypes which the Mind supposes them taken from; which it intends them to stand for, and to which it refers them' (II. xxxi. 1). If we combine this new distinction with Locke's principle for the reality of ideas-an idea is real in so far as it conforms with its archetype-it follows that all adequate ideas are real. Locke's next step is to show that all simple ideas are adequate. Since simple ideas are 'nothing but the effects of certain Powers in Things, fitted and ordained by GOD, to produce such Sensations in us', Locke argues, 'they cannot but be correspondent, and adequate to those Powers: And we are sure they agree to the reality of Things' (II. xxxi. 2, emphasis added). This is because, if simple ideas are purely given (the understanding being passive with regard to their reception), they cannot be known except by experiencing them, and only in so far as they 39 are experienced. Put differently, because simple ideas merely express the power in things to produce in the understanding such a sensation, Locke argues, they cannot fail to be the pure and full effect of that power (IV. iv. 4; cf. II. xxxi. 12). In sum, simple ideas are real on the second count as well. They conform with themselves. This means that simple ideas conform both with the real being and existence of things and with themselves. IV Having shown that all simple ideas are real on both counts, the question becomes how and when this is transferred to combinations of simple ideas, namely substance and mode ideas. I will start with the first. A substance idea emerges after a certain set of simple ideas is often experienced together without the understanding playing an active role in the formation of the set. From the repeated confrontation with a particular set of simple ideas, the understanding concludes that something without it is responsible for those simple ideas frequently occurring together (II. xxiii. 1). This attribution of an external something-or 'real essence' -to an experienced set of simple ideas is the principal contribution of the understanding to the formation of substance ideas. It is, moreover, this 'external something' that the substance idea is meant to represent, not the particular combination of simple ideas that is before the mind. Rephrasing this in Locke's ectype-archetype distinction: the set of simple ideas that makes up a substance idea is an ectype of something external, or as Locke calls it, a real essence, which acts as its archetype (IV. iv. 11; cf. II. xxxi. 13).14 * 14 Locke uses the term 'real essence' to denote the inner constitution of things as it is responsible for the occurrence of a particular group of simple ideas, and reserves the term 'nominal essence' for the group of simple ideas itself (III. iii. 15). Rephrased in terms of Locke's ectype/archetype distinction: the real essences are the archetypes 40 i r Now that the ectype and archetype for substance ideas have ' . been distinguished, it can be asked when substance ideas are real. According to Locke, substance ideas will be real when f they conform with the real being and existence of things. This t follows from the observation that a certain combination of simple ideas is often found together, combined with the recognition that we cannot conceive the simple ideas involved to exist unsuppõted, and the recognition that those simple ideas must conform with what causes them. This guarantees, first, that our substance ideas have an external origin; second, that the things themselves, which act as the* cause of our simple ideas, are structured; and, third, that where a number of simple ideas are often found together this suggests a particular structure in the things themselves that is responsible for it. This is as much as to say that the ideas thus found together are as a group the 'constant Effect' of the things themselves (cf. II. xxx. 2), which is, as with simple ideas, sufficient for calling them real. The next question is whether these substance ideas can be adequate as well, since only then they will be real also on the second count. Let us look again at the idea of gold. According to Locke, we arrive at this idea by perceiving a recurrent combination of simple ideas (III. vi. 46). For Locke this combination includes simple ideas such as yellow, heavy, hard, and malleable. As noted, however, it is not this particular collection of simple ideas which the substance idea of gold is meant to represent. Instead, the idea of gold is intended to represent the real being and existence of things in so far as this is responsible for that particular grouping of simple ideas. Two things may be noted. First, that these simple ideas are all logically independent. It does not follow, for instance, from gold being yellow, of which the nominal essences are ectypes. These real essences, however, must not be interpreted as distinct species existing among the things themselves. Locke denies the existence of such species, and explicitly criticizes the claims made by advocates of the doctrine of substantial forms (cf. II. xxxi. 6, 8; xxxii. 18). 41 *. I I ~ ) " 'I :!, ! l " ' heavy, and hard, that it must be malleable. Second, that we cannot see from the set of simple ideas itself, whether it is complete with respect to the real essence it is intended to represent, nor whether it is entirely accurate. In the course of time we may get a more accurate idea of gold by being differently exposed to it. This may lead to the discovery of new ideas which may turn out to be as intimately connected with gold as the others. This occurred, for example, when gold was found to be soluble in aqua regia. Or it may force us to modify the group of ideas that is traditionally associated with gold. The latter would occur, for instance, were it to be discovered that the yellowness of gold is caused by impurities, and that gold of itself is white. Although substance ideas may become reasonably fair representations of the real being and existence of things, at least for practical purposes, a substance idea can never become an adequate representation. This is because our faculties are limited, as a result of which we have only a partial access to what causes, say, our idea of gold. That our faculties are limited, Locke argues, is revealed in part by telescopes and microscopes (cf. II. xxiii. 12), and, more radically, by the fact that we can conceive of beings with a thousand more faculties than we have (II. xxiii. 13). We have, Locke claims, as little ground to deny that there are such beings, as a worm shut up in a drawer has to deny the existence of beings with faculties like ours (II. ii. 3). It is because of such limitations that the reality of the simple ideas is only partially retained in substance ideas. They are real only in so far as they conform with the real being and existence of things. At this point there is a notable difference compared with simple ideas. A deficiency in faculties does not affect the adequacy of any of the simple ideas perceived; it means only that certain simple ideas cannot be perceived. 42 v This brings us to the third type of ideas that Locke distinguishes, namely mode ideas. In contrast to substance ideas, which represent something without the mind, mode ideas are formed when the understanding freely combines simple ideas without the intention to represent anything besides that combination of ideas. In. this manner we obtain ideas like centaur or adultery, and even ideas that seem simple, like duration or number. From the fact that mode ideas are made sometimes 'very arbitrarily ... without Patterns, or reference to any real Existence' (III. v. 3, 6), it may not be concluded, Locke claims, that they are made at random. In their production, Locke explains, the understanding pursues its own ends (III. v. 6). In this, communication with others plays a crucial role (Ill. v. 7; II. xxii. 5; III. v. 7, 8). Mode ideas allow us, Locke argues, '[to] represent to another any complex Idea, we would have him conceive' (II. xxii. 9), by inviting him to combine the same simple ideas as those we have when we use the name. This introduces a social element into Locke's theory, one he unfortunately only hints at, in which a conformity with the ordinary use within a linguistic community comes to determine whether a mode idea is real or not (II. xxx. 4). When Adam, as Locke explains, constructs the idea of adultery after seeing that Lamech is more melancholy than usual, and calls it 'Niouph', this idea is distinctly a product of his understanding (III. vi. 44). Once the idea is formed, however, it is from then on determined which combinations of simple ideas Adam, or anyone in his linguistic community, must encounter for 'Niouph' to be applicable to something, other than Adam's voluntarily combining those ideas to express a particular thought (cf. Ill. v. 5). This means that with mode ideas the situation is exactly the reverse of that of substance ideas. Whereas substance ideas are ectypes, with the things themselves as their archetypes, mode 43 I' ideas are themselves archetypes, to which the things themselves-or real essences-may conform as ectypes (see fig. 2). Mode ideas, Locke explains (II. xxxi. 3), are archetypes themselves, made by the understanding 'to rank and denominate Things by'. They are originals, not copies (cf. III. v. 6; ix. 7; xi. 17). After the understanding created, say, the idea of a mermaid, it was from then on determined what an existing thing must conform with, for it to* be a mermaid. Since mode ideas are originals, they need not conform with anything besides themselves in order to be real, as long as 'there be a possibility of e.x.isting conformable to them' (II. xxx. 4; cf. III. x. 33). Consequently, mode ideas are real only on the second count: they conform with themselves. Fig. 2: COMPLEX IDEAS ARCHETYPES (ORIGINALS) ECTYPES (COPIES) things themselves substance ideas mode ideas things themselves We may thus conclude that Locke holds a single criterion for determining whether something we think of is real, and not two separate criteria that have, as Leibniz put it, 'nothing in common between them' (loc. cit.). This is confirmed by Locke's rephrasing the issue in terms of an archetype-ectype relation, and his application of it to the three kinds of ideas he distinguishes. The latter in particular reveals the presence of a systematic doctrine, instead of a purely ad hoc salvage operation to rescue moral philosophy and mathematics from being exiled to the realm of fiction. 44 VI It seems, however, that if the above is a correct interpretation of Locke's conception of reality, it will fail to do what Locke hoped it would do, namely, avoid treating the ideas of mathematics and moral philosophy as on a par with allegories and fairy tales. Worse even, he would still be unable to distinguish the reas<,mings of the sober man from the visions of the enthusiast (IV. iv. 1), as he set out to do. This brings us to the second part of this paper, namely, an analysis of Locke's criterion of reality. For this we should again consider what exactly makes mode ideas real. As noted earlier, for Locke, the reality of mode ideas does not depend upon a conformity with the real being and existence of things. Since mode ideas are not intended to represent things themselves, Locke argues, they are real even when there are no things themselves that conform with them. It is sufficient that things themselves can conform with them, as the example of adultery shows. This means, Locke continues, that for mode ideas to be real, it suffices that they constitute a consistent set of simple ideas. As Locke phrases it: 'there is nothing more required to those kind of Ideas, to make them real, but that they be so framed, that there be a possibility of existing conformable to them' (II. xxx. 4; cf. II. xxii. 2; xxxii. 29; IV. iv. 12). I will call this Locke's consistency criterion. In the absence of any additional criteria for the reality of mode ideas, however, this commits Locke to accepting that any set of simple ideas that can be combined consistently is real, as long as one abstains from judging whether there are things themselves that conform with it. As a consequence Cinderella's little glass slippers will be real too,. as long as we abstain from any judgement regarding their conformity with the real being and existence of things. This is because the consistency of the simple 45 ideas that are combined so as to make up the story of Cinderella, makes it possible that the story is true, however improbable this may be. Hence, far from distinguishing mathematics and moral philosophy from myths and fancies, they are still treated exactly alike. The main difference is that whereas the truths of mathematics and morality were first dismissed as fiction, now even fairy tales are to be classified as real, leaving hardly any room for anything to be a fiction, that is, for anything to be not real. The only ways remaining in which something can still be a fiction for Locke, are when one wrongly claims that a product of our imagination conforms with the real being and existence of things (II. xxx. 5; xxxii. 25), or when one combines simple ideas in an incoherent way (II. xxx. 4). Both ways, in a combined fashion, also surface earlier on in the Essay, when Locke discusses the visions of madmen (II. xi. 13). This view of the reality of mode ideas, however, brings us straight back to the point from which we started, namely Locke's desire to distinguish the reflections of the sober man from the visions of the enthusiast. If the above account of Locke's conception of reality is correct, Locke is still without the means to distinguish between the two. As long as they do not combine ideas in an inconsistent way, or make ideas represent real essences where there are none, the ideas of both have to be characterized ~s real. Consequently, Locke's conception of reality, which is introduced by him precisely to deal with this problem, fails to do what he intended. One could object to this that it ignores the fact that Locke's views on intuition and reason can sustain claims to, for instance, mathematical and moral knowledge which enable him to set them apart from other mode ideas, such as Cinderella's slippers. If we know something, either through intuition or demonstration, then what we think of must surely be real. Immediately after presenting his definition of knowledge at the beginning of book IV; Locke confirms this by explicitly contrasting knowledge 46 with fancy or fiction (IV. i. 2). However, even if we accept that , knowledge can be obtained along the lines given by Locke in the course of Book IV, this will not help us, since the opposite certainly does not hold. We may not conclude from the fact that we failed to obtain knowledge of an object that is before the understanding, that it is not real. Hence, although a study of Locke's views on intuition and reasoning may reaffirm the reality of some mode ideas, it does not follow that all other mode ideas are not real. The best we can do is to show that certain combinations of simple ideas are inconsistent, which brings us straight back to Locke's consistency criterion. One may try to overcome the limitations of this objection by rephrasing it in terms of a subjunctive conditional: a mode idea is real, as opposed to a figment, when it could be known, assuming sufficient attention and energy were devoted to it. This would have the distinct advantage that the reality of an idea no longer depends on the accidental circumstance whether knowledge of it is obtained. However, since on Locke's terms all mode ideas are adequate, this can be said of all mode ideas that are consistent combinations of simple ideas. This is because the possibility of obtaining such knowledge is entailed in the very notion of adequacy. Hence, the ultimate criterion for the reality of mode ideas is still their consistency. To this one might again object that with respect to at least some ideas of mathematics and perhaps also of moral philosophy, it is possible to obtain certainty, something that cannot be said of all consistent constructions of the understanding. We can be certain that the three angles of a triangle add up to two right ones, Locke argues, because when we perceive a triangle, we cannot conceive this to be different: When we possess our selves with the utmost security of the Demonstration, that the three Angles of a Triangle are equal to two right ones, What do we more but perceive, that Equality to two right ones, does 47 ,I necessarily agree:.to, and is inseparable from the three Angles of a Triangle? (IV. i. 2) This certainty we obtain, in Locke's view, from a perception of the agreement and disagreement of our ide~s. This perception can be either immediate, in which case Locke speaks of intuitive knowledge, or through the mediation of other ideas, in which case he speaks of demonstration (IV. ii. 1 ff.). On the basis of this, one could argue that at least some mode ideas can be set apart, namely, those that are not merely perceived as a possibility (in virtue of their being a consistent combination of simple ideas), but of which it is also perceived that the ideas that are combined in them cannot be otherwise than thus combined. This leads to what I will call Locke's inconceivability criterion: We can be certain that the three angles of a triangle add up to two right ones, because it is inconceivable that they should add up differently. As a result, Locke argues, we cannot 'conceive this Relation ... to depend on any arbitrary Power, which of choice made it thus, or could make it otherwise' (IV. iii. 29); that is, it cannot be a product of our fancy, which means that it must be real. The same conclusion can be obtained along a slightly different line. Because it is inconceivable that the angles of a triangle should add up otherwise than to 180 degrees, we can be certain that their sum is 180 degrees. This means, Locke argues, that we know that the three angles of a triangle equal two right ones (IV. i. 2). Since, as was noted earlier, the object of knowledge-as opposed to that of belief or opinion-is a real idea and not a fiction of our fancy, we can derive from the fact that we know that the angles of a triangle equal 180 degrees, ~hat it is a real fact that their sum is 180 degrees. In sum, using the inconceivability criterion, Locke can classify some mode ideas as real in a way that does not commit him to calling all consistent constructions of the understanding real. 48 This, in turn, allows him to distinguish between the careful deliberations of the sober man, which result in knowledge, and the visions of the enthusiast, which fall short of knowledge. It appears, however, that this inconceivability criterion is not without problems of its own. First, assuming the criterion to be valid, one could object that again too much must be dismissed as fiction, and that therefore it fails to distinguish properly the careful considerations of the sober man from the reveries of the enthusiast. It would commit us to saying that only those mode ideas of which it cannot be conceived that they are not so combined, would qualify as real. The perception that a certain group of simple ideas cannot be conceived to be otherwise than thus combined, includes besides the recognition that they cannot be combined in any other way, also the recognition that they cannot be not combined. Apart from the objection that the inconceivability criterion dismisses too much as mere fiction, one could argue that the criterion is of itself untenable. Inconceivability may be a necessary condition for a certain combination of simple ideas to be impossible, but it is not a sufficient condition. This is because sometimes what we conceive to be impossible, turns out to be possible after all, as can be illustrated with Euclid's famous axiom that the whole is always greater than its parts. This axiom, which was thought to be necessarily true on the ground that its denial could not be conceived-with which it fits Locke's characterization of intuitive knowledge-was proved to be wrong by Georg Cantor well over two millennia after Euclid formulated it. Cantor showed that a subset of the integers-those that are even-can be put into a one-to-one correspondence with all integers, since for each integer there is a number that is its double, which is always even. Because of this one-to-one correspondence there are as many integers as there are even numbers. At the same time, however, the even numbers make up only half of the integers, odd numbers making up the other half, since 49 there is an odd number between any two subsequent even numbers. IS Hence, there are at least two major problems with the inconceivability criterion. First, if it is used to distinguish real from fantastical mode ideas, it commits us to saying that only those mode ideas that consist of combinations of simple ideas that cannot be otherwise than thus combined are real. Second, the immediate perception that ideas cannot be otherwise than thus combined, does not by itself guarantee that the ideas must indeed be thus combined. Because of the latter we cannot use Locke's conception of intuitive knowledge as a means to set apart certain mode ideas as real, even should we accept the limitations that come with this new criterion. As a result, Locke remains committed to his claim that all mode ideas that are consistent combinations of simple ideas are real; meaning that he is still unable to distinguish the careful considerations of the sober man from the visions of the enthusiast, as long as the latter's ideas remain internally consistent.16 ts Both the example and the argument are derived from C. S. Peirce. See C. Hartshorne & P. Weiss (eds), Collected papers of Charles Sanders Peirce (Cambridge, MA 1931-58), vol. 2, sections 29-30. 16 Special thanks go to Susan Haack for her comments on earlier versions of this paper. Responsibility for any mistakes or weaknesses, however, remains entirely my own.