Aristotle on Being: an Aristotelian Critique of Russell's Theory of Existence George Couvalis Aristotle explains existence through postulating essences that are intrinsic and perception independent. I argue that his theory is more plausible than Hume's and Russell's theories of existence. Russell modifies Hume's theory because he wants to allow for the existence of mathematical objects. However, Russell's theory facilitates a problematic collapse of ontology into epistemology, which has become a feature of much analytic philosophy. This collapse obscures the nature of truth. Aristotle is to be praised for starting with a clear account of ordinary objects rather than immediately reifying mathematical objects. He thus allows us to have a coherent account of existence and truth, and to easily resist collapsing ontology into epistemology. 1. Introduction Let me start with a strange question inspired by David Hume. Suppose you experience a vivid, coherent, and long lasting hallucination. In your hallucination, there appear to be persistent material objects that appear to relate to each other as we would expect material objects to relate. It seems as if your best scientific experiments show them to be made of scientifically respectable particles. And so on. What is the difference between what you experience and a real world? Note that my question does not appear to be a question about how we tell the difference. It seems we may not be able to tell, even though there is a difference. The question seems not to be a question in epistemology. Nevertheless, as we will see, Hume in his Treatise turns an epistemological claim into an ontological claim to answer our question. 2. Hume on Being Hume says that if we have an idea of existence as such or external existence as such (existence outside of our own minds), we must have an idea derived from some experienced impression. However, when we conceive of a thing and then conceive of GEORGE COUVALIS 40 it existing, there is no experienced difference at all. "The idea of existence, then, is the very same as the idea of what we conceive to be existent ... That idea, when conjoin'd with the idea of any object, makes no addition to it" (Hume, 2007a:48). In a letter in which Hume replies anonymously to the critics of his Treatise of Human Nature he adds "...the author [Hume] hath said, that we have no general Idea of Existence, distinct from every particular Existence" (Hume, 2007b:428). Hume argues that there is a difference between what we call external existence and mere existence, though it is not a difference that has to do with having an experienced impression of existence. The clusters of impressions which we call experiences of external objects are more systematically connected with each other and with other experiences, more durable and more vivid (Hume, 2007a:49). Pretty obviously, the vivid and enduring hallucination I described would meet this criterion. On Hume's argument, it must be a perception of external objects.1 Hume's account of external existence in the Treatise has the implausible consequence that external objects are mere clusters of connected and durable impressions, or perhaps of actual and possible connected and durable impressions. Such views have been criticised in great detail in the philosophical literature and I do not want to criticise them further here. The problem seems to arise from Hume's assumption that if existence is to be a property, it must be an experienceable property possessed by every existing object. 3. Russell on Existence In the early twentieth century Russell, adapting Frege, produced a sophisticated account that incorporated some of Hume's claims. Russell's account is enormously influential. It is now so widely accepted that it might be called "the canonical account" of existence. Russell explains existence by saying that any properly understood statement "... exists" has the logical form "there is an x, such that x is a...". He calls this logical form "a propositional function". As he puts it "[E]xistence is essentially a property of a propositional function. It means that the propositional function is true in at least one instance. If you say 'There are unicorns', that will mean 'There is an x, such that x is a unicorn'" (Russell, 1918:204). The instances that exist are the only items there are to pick out and "there is an x such that..." picks them out and attributes predicates to them.2 1 The view Hume puts here may not be his own ultimate position. He may have been a realist. In any case, Hume changed his mind about the merits of the account in the Treatise in later work. However, he never produced a satisfactory account of existence. For details see Bradford, 1983 and Cummins, 1991. Fred Wilson tries to partly rescue Hume through speculating about Hume's view of abstract ideas (Wilson, 1991). However, even on his interpretation, Hume's view is wrong. 2 Russell's view is sometimes described as the view that existence is a second order property, a property of properties (Caplan, 2006). However, this is not correct. Russell explicitly says that existence is a property of a propositional function, which is not a property. Further, being a unicorn cannot be a property, for ARISTOTLE ON BEING: AN ARISTOTELIAN CRITIQUE OF RUSSELL'S THEORY OF EXISTENCE 41 In giving reasons for adopting the canonical account, Russell denies that "existence" is an ordinary predicate. He argues that existence cannot be some property that all things individually necessarily possess because if a thing with some property can be picked out it must already exist. Further, a property all individuals necessarily possess cannot be a real property (Russell, 1918:204–5). In explaining this through a joke, he comments that "... it is obvious that, if you think of the things there are in the world, they cannot be divided into two classes - namely those that exist and those that do not. Non-existence is, in fact, a very rare property. Everyone knows the story of the two German pessimistic philosophers of whom one exclaimed: 'How much happier were it never to have been born'. To which the other replied with a sigh: 'True! But how few are those who achieve this happy lot'" (Russell, 1956:147). Having explained the reasons Russell later gave in favour of the canonical account, let me point out that it is clear that his initial reason for adopting it is that it would allow mathematical objects to be respectable existents. While he is an empiricist rather like Hume about the objects of science and perception, Russell holds that logic and mathematics are in some sense telling us about another kind of real object. In a 1905 paper, Russell argues that "exists" has two distinct senses. In the first sense, it is predicated of individuals and is standardly used in every day life, as when we say that Hamlet does not exist or that Socrates existed. The second sense, which he says is only used of the objects dealt with in symbolic logic such as numbers, is the sense he made canonical. Russell barely bothers to discuss the first sense in 1905, and it is clear that he thinks it is of little interest (Russell, 1905). By the time he wrote the work we are discussing, he had come to think that the second sense is the only coherent sense of "exists" and is applying it to talk of unicorns. Russell's motives in dropping the first sense of existence are clarified in a 1913 manuscript in which he discusses Hume's account of existence and claims that "[S]o long as it was thought that "existence" ... could be significantly predicated of an actual given particular, it was impossible to answer Hume's contention that existence adds nothing to the subject..." (Russell, 1913:138–139). The canonical account can be used to deal easily with an ancient problem raised by Parmenides, which is: how can we talk about non-existent objects? If you talk about them it seems they must exist. Following Russell, we can say that we don't talk about them. We instead talk about things (instances) and truly or falsely predicate something of at least one of them. The claim that some kind of thing does not exist is made true by no instance bearing that predicate. Unlike Hume, Russell can explain very simply how we can think of something that does not exist and, indeed, think that it does not exist. unicorns do not exist, so the property of being a unicorn does not exist. Russell formulates a theory of the meaning of "exist" that is in part intended to explain how we can meaningfully state something false when our propositional function apparently refers to a non-existent property. He explains this by saying that such propositional functions are formed by concatenating names of existent properties in a logical construction. The details are not relevant here. GEORGE COUVALIS 42 Russell's canonical account is more sophisticated than Hume's. However, as he provides us with no explanation of what it is to be an instance, it is difficult to see how he could produce a principled account that rules out (or rules in) the contents of hallucinations as existents. Further, in what we have discussed there is no account of external existence. Russell gives an account of external existence that is not very different from that of Hume in the Treatise. He thinks that phantoms and images are not fundamentally different from external objects except that "[I]f you shut your eyes and imagine a visual scene and you stretch out your hand to touch what is imaged, you won't get a tactile sensation, or even necessarily a tactile image. You will not get the usual correlation of sight and touch... The general correlations of your images are quite different from what one chooses to call 'real' objects. But that is not to say that such images are unreal, it is only to say that they are not part of physics". He goes on to give a similar account of Macbeth's dagger: "Macbeth sees a dagger. If he tried to touch it, he would not get any tactile sensation, but that does not imply he was not seeing a dagger, it only implies that he was not touching it. It does not in any way imply that the visual impression was not there" (Russell, 1918:224). Russell's view of external existents is a form of neutral monism in which the view of one perceiver is supplemented by the views of others, and in which psychological phenomena are explained by different laws to physical phenomena. Nevertheless, the components of the psychological and the physical world are the same kind of thing - this is why neutral monism is a monism. On Russell's account the components of the world are actual and possible sense-data, which are strikingly like Hume's impressions.3 He embraces neutral monism because he rejects as spooky the view that mental states are directed to objects that exist in some separate world - the view that Macbeth's dagger exists separately from Macbeth's experience because it is an object of Macbeth's thought. By contrast to the supposedly spooky view, neutral monism does not radically distinguish between the object of an experience and an experience - it seems more scientific and less mysterious (Grayling, 2003:461–2). As we have seen, it also does not radically distinguish between psychological existents and physical existents.4 While Russell's account is an advance on that of Hume, he ends up in an implausible neutral monism that is subject to the same sorts of objections as Hume's empiricism. I do not want to repeat criticisms of neutral monism here. It is sufficient to note that it is difficult to avoid neutral monism or something like it when we assume 3 Nicholas Griffin has denied that neutral monism is like phenomenalism because neutral monism includes unsensed sensibilia and spatially located sense-data (Griffin, 2003:30). However, Humean phenomenalism arguably also includes unsensed but possible impressions, and Hume argues that spatial relations are constructed out of relations between impressions. So the difference is trivial. 4 I am oversimplifying in the above discussion. Although Russell was sympathetic to neutral monism when he wrote Russell, 1918, he did not subscribe to it until soon after. He then substituted "percepts" for "sense-data". ARISTOTLE ON BEING: AN ARISTOTELIAN CRITIQUE OF RUSSELL'S THEORY OF EXISTENCE 43 that external existents cannot have anything in common which makes them external existents. Russell also ends up very implausibly putting the objects of mathematics and logic on a par with ordinary external existents through a logician's device when he uses the notion of a propositional function to explain all talk of existence. Perhaps a case can be made that mathematical and logical objects exist in some sense of "exist". However, the starting point in an account of existence should be a plausible account of the paradigmatic examples of existents, external existents. 4. Aristotle on Being Let us return to my strange question. We will see that Aristotle does not think it can be answered through epistemology. He thinks it is a question about being. Indeed, Aristotle defines metaphysics as ontology, which he calls "episteme tis he theorie to on he on", which means the science which studies being qua being (1003a1). We can glean Aristotle's answer to my question from his criticism of Protogaras' view that all appearances are true in book Gamma of Metaphysics. He there contrasts his view which says some things are "auta kath' auta", things which are what they are through themselves (literally, themselves through themselves), with Protagoras' view which "apanta poeii ta onta pros ti", makes all things relative to perception (literally, makes all beings relative) (1011a18–21). (Protagaras, who was an extreme empiricist, can be plausibly taken to be an intellectual ancestor of Hume and Russell.) In context, it is clear that what Aristotle means is that the world of external existents is perceiver independent. The identity of the items in it is given through themselves. By contrast, the hallucinated items are not something through themselves - their identity is dependent on a perceiver. However, the hallucinated items are represented by the perceiver as existing in themselves. The falsity of the representation consists in there not being anything represented which exists in itself - that is, Aristotle holds that the falsity or truth of representations is to be explained through being, not that being is to be explained through the truth or falsity of representations. This is particularly obvious in his account of truth and falsity in Metaphysics Theta 10. In Theta 10, Aristotle lists truth and falsity as one of the three key ways in which something is said to be. He then presents the view that being true is derivative from being and not from thinking (or, presumably, experiencing). He illustrates his view by remarking that "... it is not because of our truly thinking you to be pale that you are pale, but is rather because you are pale that we who say this speak the truth".5 Aristotle's definitions of truth and falsity in book Gamma of Metaphysics are also in terms of being (to on) 1011b26–29. Aristotle might be thought to be stating the theory of truth produced by the logician Tarski, according to which the statement or representation "P" is true if and only if P. However, it is clear from remarks in Metaphysics that he is also committed 5 Makin, 2006's excellent translation of 1051b8–10. GEORGE COUVALIS 44 to the stronger claim that "P" is true if and only if there is truth-maker P which is independent of what anyone thinks or perceives.6 What is for something to be auto kath' auto? What is it for something to be a truthmaker? We might think that Aristotle claimed that there is some obvious property that externally existent objects have in common but the objects of representations do not. A real dagger has a property that Macbeth's dagger does not have. This, however, does not fit some of the things he says. In Metaphysics Delta he says that the beings in themselves are what is signified by the (differing) schemata of the categories of being (i.e. quantity, quality etc.) (1017a22–3). In Metaphysics Zeta the point is explained when he says that being in itself is said in many ways ("to on legetai pollahos") and lists the categories in which it is said (e.g. of quality, of quantity, substance, and so on) (1028a10–13). Does this mean that he claims that the term "being" is equivocal and means something different when talking about different categories? Along with most commentators, I don't think so. In my view Aristotle was in part putting a similar point to that of Hume, which is that when we say that something exists, nothing from a specific category is being predicated of it. When we say that paleness exists or that weighing five kilograms exists, neither of those statements is predicating something from another category of them. Existence is not a category, nor does it come under a category. It is not a kind of being, like a quality or a quantity. Hence, existence is not a property that can be used to pick out instances. What then is it to be an itself through itself? What is it to be a truth-maker? In Book Zeta of Metaphysics and elsewhere Aristotle answers these questions by saying that there must be a ti einai of that thing - something that it is to be that thing independently of thought or perception. I have pointed out in a previous paper that he argues that this means that the thing must have an essence (or consist of things that have essences). An essence is a property that defines a thing, and without which it cannot exist (Couvalis, 2011). Without essences there cannot be anything that it is to be something. This means that when I say something exists, I am asserting that it has essential properties or is made up of things that have essential properties. If you like, to be is to have the second order property of having essential properties that are independent of perceivers.7 The essential properties can belong to various categories of being Aristotle describes in Categories. Existence is a property but because it is a second order property shared by all things, it is not a property that can be used to pick them out.8 Let us take an example to illustrate Aristotle's view. Suppose I perceive a cat. To say that the cat exists is to say that it has the essential property of being a cat independently 6 Crivelli has plausibly argued that there are some differences between Aristotle's theory and modern truth-maker theories. For instance Aristotle thinks states of affairs themselves can be true, so that "true" does not apply merely to sentences (Crivelli, 2004). This is not relevant here. 7 My account is inspired by Hintikka, 2004. 8 The view of being I ascribe to Aristotle is similar to the view William of Ockham defends (Ockham, 1957:90–94; Pelletier, 2012:99–101). ARISTOTLE ON BEING: AN ARISTOTELIAN CRITIQUE OF RUSSELL'S THEORY OF EXISTENCE 45 of my perception. By contrast, if I hallucinate a cat, the object of my false representation has no essential properties. The cat content is, as Aristotle would put it, pros ti - relative to something. Presumably it is relative to a perceiver. (Of course, my representation may itself have an essential property that makes it a representation. It may also have an essential property that makes it a representation of a cat. However, that is a different essential property.) The reader may be puzzled by the fact that Aristotle seems to elsewhere say that only substances (ousiai) have essences. In Book Zeta he says that although the focal meaning of essence means that only substances have essences, other items, such as those in various categories, have an essence; though not in an unqualified way (1030a 17–27). I take it that he means by this that a quality or a quantity is a property of some other thing that is not a quantity or a quality (e.g. of a man). However, being a man is not a property of anything else.9 Further, substance essences are causally explanatory in themselves for Aristotle whereas quality or quantity essences are not causally explanatory in themselves as they are modes of being of substances. Note the difference from Hume. Hume assumes that if there is to be an intrinsic difference between objects in hallucinations and real objects there must be experiencable differences between them. If being in itself is a property (or defined in terms of properties), it must be experiencable. A property like having essential properties that are independent of how they are conceived or perceived is ruled out by Hume's collapsing of ontology into an empiricist epistemology. Hume cannot canvas the possibility that being might be a second order property of properties. Of course, Russell's account is considerably more sophisticated than Hume's because it introduces the notion of a propositional function. We might think that if the problems introduced by Russell's neutral monism could be overcome, his account would be fine. However, Aristotle would argue that Russell's propositional function account of what it is to be fails to deal with the central question, which is to explain what it is for a purported property to be instantiated. For Aristotle, if such an account is not to be empty, it must rely on a pre-existing notion of being which is built into the notion of an instance. That is one of the points underlying his account of truth. So, for Aristotle, Russell's account would be circular. 5. Conclusion A sense of "exists" Russell introduced to make sense of logical talk about strange entities such as numbers has become the only sense that many analytic philosophers think is coherent. This reflects a tendency introduced by Russell into analytic philosophy to pretend to scientific naturalism while being a radical empiricist with Platonic leanings. The tendency is Platonic in that it takes supposedly precise and 9 I follow the interpretation of Bostock, 1994:92–93, without endorsing his criticism of Aristotle at Bostock, 1994:94. GEORGE COUVALIS 46 well-defined ways of talking about abstract objects to be the proper guide to talking about existence in general. The influential empiricist philosopher Quine is an exemplar of this tendency, despite his many attempts to escape from the Platonic tendencies of past philosophy. In his paper "On What There Is", one of his central obsessions is logical and mathematical existence (Quine, 1948). He accepts the canonical account without serious argument but quibbles about specific cases. His detailed arguments for the existence of some things and against the existence of others there and elsewhere are notable because they discuss in considerable detail epistemological criteria for deciding whether something exists, such as simplicity in accounting for experience. However, the apparent clarity and precision of Quine's version of the canonical account rests on sheer evasiveness about the notion of an instance. Unlike Hume, he does not explicitly collapse ontology into epistemology, but he implicitly does so. He also discards the notion of an essence. Aristotle would have thought that like Hume, Quine is unable to give a plausible account of the central case of existence, external existence. All he can do is talk about epistemological criteria for deciding whether some propositional functions are instantiated. Further, Aristotle would have thought that Quine renders it utterly unclear what it is for some claim to be true as Quine's account seems incapable of yielding an adequate theory of truth. As Quine thinks that things do not have essences independently of our descriptions of them he is unable to give a plausible account of what it is for some claim to be true (Book Theta of Metaphysics makes clear that Aristotle thinks that to explicate "to be true" we must first have an adequate account of what it is to be something). More modern debates about existence in analytic philosophy are plagued by a related problem. One debate beloved by the logically minded is the debate initiated by Meinong as to whether the objects of intentional states exist.10 All kinds of strange considerations about what we logically quantify over have been introduced to deal with such cases. However, these debates rely on no clear account of what existence is in the central case of external existence. They often assume the claim that things like numbers exist can be clearly understood and then go on to extrapolate to other cases. Obscurantist talk that masquerades as explanatory is introduced. By contrast to the tendency introduced by Russell into analytic philosophy, Aristotle's account of existence starts by affirming the primacy of the sense of "exists" involved in external existence. He takes over Plato's jargon (auto kath' auto, ousia etc.) but he subverts it to make the world of everyday perception and science primary in discussing existence and not the spooky world in which Platonists think mathematical objects and the like reside. 10 For a brief account of the problems the Meinongian view was meant to address, see Caston, 1998. Caston very clearly explains Aristotle's naturalistic and anti-Meinoningian solution to such problems. 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Ross (ed.), Aristotle, Metaphysics, Volumes 1 and 2. Oxford: Oxford University Press. GEORGE COUVALIS 48 Russell, 1905 B. Russell, "The Existential Import of Propositions", as reprinted in The Collected Papers of Bertrand Russell, 4. A. Urquhart ed. London: Routledge, 1994:486–489. Russell, 1913 B. Russell, "Theory of Knowledge", as reprinted in The Collected Papers of Bertrand Russell, 7. E. Eames and K. Blackwell eds. London: Allen and Unwin, 1984:5–178. Russell, 1918 B. Russell, "The Philosophy of Logical Atomism", as reprinted in The Collected Papers of Bertrand Russell, 8. J. Slater ed. London: Allen and Unwin, 1986:157–244. Russell, 1956 B. Russell, Portraits from Memory. New York: Simon and Schuster. Wilson, 1991 F. Wilson, "Hume on the Abstract Idea of Existence", Hume Studies 17:167–202. I would like to thank Lina Eriksson, Chris Mortensen and Scott Mann for helpful comments on a draft of this paper.