Reflections on Metaphysical Explanation Rögnvaldur D. Ingthorsson The nature of metaphysical explanation is a question that should be constantly on every metaphysician's mind, and yet it is rare to see explicit statements about the methodological approach that writers take. We tend to just enter the flow of ideas and words in a particular 'discourse' and see where it leads us. It is easier that way but can lead us astray. I can't claim to be a role-model in this respect. I have offered a comment here, a remark there, but plenty room for improvement. However, I have come across quite a few confusions that can be traced to failed understanding of method/approach, and one or two really interesting statements of method. Here I share one such confusion about method, and one interesting view about method. 1. A confusion about Hobbes The necessity of causal connections is usually associated with causal realism. Say, Aristotle's claim that "whenever the potential active and potentially affected items are associated in conditions propitious 136 to the potentiality, the former must necessarily act and the latter must of necessity be affected" (Metaphysics: Bk. 9, §5). For Aristotle, this is not the result of an a priori argument outlining a logical/conceptual necessity, but a consequence of a certain view of material reality; objects with powers interact to provoke changes in each other. I have always supposed that this was the view Hume targeted (Treatise: Bk. I, Part 3). However, in Elizabeth Anscombe's famous discussion of causal necessity, we see Hobbes being represented as Hume's target and as someone who 'evidently' sees causal necessity as a "logical connection of some sort" (Anscombe 1971: 89). To be sure, Hobbes does incriminate himself in the following passage: [...] an entire cause, is the aggregate of all the accidents both of the agents how many soever they be, and of the patient, put together; which when they are all supposed to be present, it cannot be understood but that the effect is produced at the same instant; and if any one of them be wanting, it cannot be understood but that the effect is not produced (Hobbes 1656: Ch. X, §3) However, I think Anscombe is wrong to infer from Hobbes' use of the phrase 'cannot be understood' that he is developing a purely logical argument, at least not of the a priori kind. Hobbes' epistemology is empiricist, albeit with clear rationalist overtones. He thinks the senses provide us with empirical knowledge about the powers of material bodies, and thus knowledge of causes, because powers are causes (Hobbes 1656: Ch. I, §4). From our empirical knowledge of these causes we can then rationally calculate the effects they produce, and, vice versa, the causes from the effects. In light of this, I think it would be more charitable to interpret Hobbes as making claims about what can/cannot be thought, given the na137 ture of the external world as it is empirically known to us (or assumed). This could offer a basis for a deductively valid argument, yes, but using premises with material (non-logical) content which is empirically true; hence the conclusion is a posteriori of experience. If we find fault with his claims about what can or cannot be understood, we should find fault with his empirical knowledge and not with his logic. Consider the same reasoning in the early 18th century, from someone with knowledge of Newton's Principia. That person could argue like Hobbes that-if Newtonian mechanics is accepted as a true description of the world-it cannot be understood, on pain of contradicting Newton's mechanics, but that if an object is acted upon by an external force it will change its state of motion in proportion to the force applied. It is a logically valid argument, but moving from premises based on empirical research, and so the conclusion is a posteriori. The approach suits a naturalist approach to metaphysical explanation. Indeed, Naomi Thompson (2019) outlines something very similar. On her view, metaphysical explanations are subject to epistemic constraints imposed by the context in which a question is asked; they are not explanations of what must be the case without regards to any concerns except what can or cannot be conceptualised. Hume may well have had Hobbes in mind. But he didn't just attack his logic. Hume first had to deny Hobbes' premise that the senses give us knowledge of the nature of external objects, and thus turned the question of causation into a mere conceivability issue; one unrestrained by epistemic concerns (Treatise: Bk. I, Part 3). Now, it is difficult to assess today in what way exactly it can have mattered that Anscombe misrepresented Hobbes' position. But we can tell that it did matter. 138 2. McTaggart's approach to metaphysics McTaggart's The Nature of Existence (1921/1927), is well known for containing McTaggart's argument for the unreality of time. It is less well known for containing a long and very interesting elaboration of metaphysical method. Indeed, he devotes the whole of chapter 3, 'Method', to an elucidation of his approach. Contemporary readers may be even more surprised to find out that we can find something useful about metaphysical explanation in the writing of a self-confessed Hegelian idealist. It is important to note that McTaggart is an idealist in two different ways. First, he is an idealist with respect to the method of metaphysics; a methodological idealist. He thinks we can only gain knowledge about the ultimate structure of reality-which is the aim of metaphysics-through an examination of the general content of our ideas; not through a study of the content of our experiences of particular matters of fact. Empirical observations are inadequate to the task because they are particular both with regard to the qualities observed and the identity of the entities observed, while the ultimate structure of reality will have to be perfectly general. We might be able to infer by abstraction from a number of particular observations that they have some general feature in common, but this would fail to show that this general feature belongs to more than just the limited sample we have observed. Instead, McTaggart believes (we may be tempted to downgrade this to hopes) that the rational mind is able to directly 'grasp' the general nature of the fundamental features of reality via rational reflection of the ideas we have about them. In other words, his preferred method of finding out about the ultimate structure of reality is by introspective reflection on the general content of our minds. 139 Today it is popular to ridicule idealism as a silly idea from the past, but in actuality much of contemporary metaphysics cannot really be distinguished from idealism. Whenever anyone focuses solely on the conceptual connections between ideas in their philosophy, which is the essence of a priori philosophical reasoning, they are doing pretty much what the idealists thought philosophy is all about. Indeed, anyone who thinks that the theories and findings of empirical science is irrelevant to metaphysics because it can only tell us about the actual world-just one manifestation of all the possible worlds allowed by the ultimate structure of reality-are applying a method I find difficult to distinguish from McTaggart's. Second, McTaggart is an idealist with respect to the nature of reality; an ontological idealist. This is perhaps the aspects of idealism that tends to be ridiculed. He thinks he can show that reality cannot fundamentally be material, and that therefore reality must instead consist of spiritual substance (ideas). His argument for this conclusion is pretty much identical to Berkeley's, notably that we are mistakenly inferring from the fact that we are acquainted with phenomenal properties in experience, that there must be something nonphenomenal that is causing the experience. Now, we may not want to accept this argument as proof of the conclusion that there is no material reality outside the mind. But, I think we should pay attention to the importance McTaggart bestows on subjective experience, as a way to judge the success of metaphysical theories. I think it holds good for idealists and material realists alike. 140 3. Taking experience seriously According to McTaggart, the way things appear to be in experience does not give us knowledge about what things are really like. Even an idealist can distinguish what ideal reality appears to be like and what it is really like. He nevertheless thinks that the content of our experience provides an important criterion for the success of metaphysical theories. A metaphysical theory need not portray reality as it appears to be in experience. Indeed, such a theory is often trying to say what things are really like, as opposed to what they appear to be like. However, since the content of experience constitutes a rare type of certain and indubitable knowledge-what Russell called 'knowledge by acquaintance', notably of our own inner states- every adequate metaphysical theory must be able to explain how the experiences we actually have can arise. If it says the world is not as it appears to be, it must be able to explain how it can appear to be otherwise To calm the jitters of hardcore realists, let's be clear about the limits of knowledge by acquaintance. It is a form of knowledge that doesn't extend beyond the content of the experience itself. My experience of an apple on a table indubitably constitutes knowledge of the state of my mind, notably that I am having an experience of that kind. But, it does not constitute knowledge of whether there is in reality an apple on the table. However, since the former is indubitable knowledge, our account of reality must take into account the fact that reality contains my experience of an apple on a table. McTaggart's idea, roughly, is that any theory about what things are really like can be tested by asking whether it offers a conceptual model of reality that explains why things actually appear to us in the way that they do. The model need not resemble the appearance, but if it differs from the appearance it must explain what it is about the 141 world that allows it to appear so different from what it really is. As long as the model cannot explain the characteristics of experience, the facts of experience constitute an anomaly for the theory. On the other hand, when we have a model that claims the world is different from experience, yet is able to explain how it can appear in the way that it does, the appearance becomes a phenomenon bene fundatum; a well-founded datum of experience (McTaggart 1927: §494). I think we can observe that many of the core disputes in metaphysics revolve around the question of how well theories explain experience. For instance, presentism is meant to have the upper hand on eternalism in explaining why we only ever experience the present. Not just because presentism says the world is pretty much as it appears to be, but more because eternalism cannot adequately explain how we can have a continuous experience of successive states and of ourselves as continuously remaining in the present, when in fact nothing exists continuously through time or moves from one time to another. For all its other faults, McTaggart's philosophy has one piece of good advice; take experience seriously as a criterion of success for metaphysical explanations. References Anscombe, G. E. M. (1971). Causality and Determination, in M. Tooley & E. Sosa (eds.), Causation, 1998, Oxford: Oxford University Press. Aristotle, (1924). Aristotle's Metaphysics, W.D. Ross (ed.), Oxford: Clarendon Press. Hobbes, T. (1656). Elements of Philosophy Concerning Body, in W. Molesworth (ed.), The English Works of Thomas Hobbes of Malmesbury, 1839, London: Bohn. Hume, D. (1739). Treatise of Human Nature, edited by L. A. Selby–Bigge, 1896, Oxford: Clarendon Press. McTaggart (1921/1927), The Nature of Existence, Vol. 1 & 2, Broad, C.D. (ed.), 1988, Cambridge: Cambridge University Press. 142 Thompson, N. (2019). Questions and Answers: Metaphysical Explanation and the Structure of Reality, Journal of the American Philosophical Association 5 (1), 98–116.