This profile is a complement to the written interview with Mark Johnston published here.
There’s a certain kind of speculative metaphysics that – between logical positivism, Wittgenstein, and ordinary language philosophy – looked for a time to be endangered. The logical positivists believed that, strictly speaking, it was nonsense (along with a great much else); Wittgenstein agreed, adding that it was essentially pathological; and so did ordinary language philosophers, apparently resenting the implication that they might have to stray from their armchairs, even in thought. The philosophical tradition that is the legacy of these movements is still known as analytic philosophy – ‘analytic’ obliquely referring to the method of linguistic analysis – but their shared anti-metaphysical temperament seems to have vanished with scarcely a trace. ‘Philosophy is aimed at knowledge of reality’, Mark Johnston tells me, towards the end of a several-hour interview in which it has been mooted that the material universe is fundamentally malign; that there are up to infinitely many morally significant beings coincident with me; and that persistent entities are five-dimensional, with parts scattered across the modal multiverse. ‘It is about the understanding of reality, not of our concepts. Cognitive science is the discipline that tells us what our concepts are like. Philosophy is about a total vision of reality and our place in it.’
Johnston is the Henry Putnam University Professor of Philosophy at Princeton, most famous for his work in the philosophy of mind and the philosophy of religion, and on personal identity. It is sometimes said that the two routes into philosophy are from religion and from science. That Johnston began doing philosophy shortly after leaving a Catholic seminary and is now Director of Princeton’s Program in Cognitive Science seems to suggest that there is still some truth to this remark. It also serves, perhaps, as a tidy parable about contemporary trends in analytic philosophy: one starts off, as Johnston did, identifying with the existential aspects of Descartes’ Meditations – and winds up, decades later, a cognitive psychologist.
In many ways, Johnston came up in philosophy at a time of significant transformation – although that it was such a time is partly a reflection of Johnston’s own influence. He took his PhD at Princeton (where he has remained ever since) in 1984, under the supervision of Saul Kripke and David Lewis, the two most influential figures in contemporary analytic philosophy. Johnston recalls the gestalt shift that came with publication of Kripke’s Naming and Necessity, which crystallised a radical change in how philosophers understood the relation between different areas of philosophical enquiry; in particular, it refuted the reduction of the metaphysical distinction between the necessary and contingent to the epistemological distinction between the a priori and the a posteriori. ‘I remember the first tutorial I had, when I was just coming into philosophy’, Johnston says. ‘Of course it was against a conceptualist background, so the necessary was a priori, and the contingent was a posteriori. And the tutor said, “Ah, but there’s this funny paper. It’s quite long. It claims that there are a posteriori necessities, and a priori contingencies.” It was like hearing that it didn’t follow from p and q that p, or something like that.’ By now, of course, the situation is rather the opposite: somewhat ironically, not just is the modal distinction between the contingent and necessary no longer believed only to be meaningfully if cashed in epistemic terms, it is widely regarded as more secure than the epistemological distinction itself.
Johnston himself was an early convert to anti-conceptualism, and much of his early work, by repudiating what he came to call the ‘method of cases’, served to further undermine the still dominant conceptualist picture. While the use of thought experiments ad nauseam is perhaps most familiar from the post-Gettier literature in epistemology – in 1963, Edmund Gettier apparently showed that knowledge was not justified true belief, and so for decades epistemologists wielded progressively more baroque counterexamples against each other, to refute progressively more byzantine analyses of knowledge – they were also prevalent in one of Johnston’s own areas of research, personal identity. ‘Really quite early on’, Johnston says, ‘I thought the reliance on such a method – whereby you come up with an intuition of some sort about whether someone survives under certain conditions, and then try to codify your intuitions in terms of necessary and sufficient conditions – was mistaken. I take it that the philosophical ideology behind it was that we are masters of our concepts – where being a master of a concept is knowing, at least implicitly, its application conditions – so, if we’re successful, the necessary and sufficient conditions that we formulate as a result of sufficient mastery of the concept over imaginary and real cases will be a conceptual truth. Whereas I thought it was a very difficult theoretical and empirical matter what our essence, if any, was, and couldn’t be settled in that way.’
‘In particular,’ Johnston continues, ‘I knew a little bit back then and I know a lot more now about the empirical psychology of our concept use, and the way in which our application of terms is not guided by grasp of necessary and sufficient conditions.’ Rather, Johnston says, mentioning important work on generics (sentences like 'birds can fly') by Sarah-Jane Leslie, who is also a philosopher at Princeton, ‘we’ve got these generic criteria, which are not universal in form, and play the role of getting us through the ordinary range of cases without any complications – which make for mutual understanding across those cases. When you consider a case like teletransportation, where bodily continuity and psychological continuity come apart, and you ask yourself your intuition in that case, you’re supposed to take that as some kind of evidence – if you have a clear intuition – as to what the conceptual truths about personal identity are. But that last step depends on assuming that our concept use is guided by necessary and sufficient conditions, rather than these generics restricted to the main line of cases.’ It’s not, Johnston adds, that we lack information about personal identity – much the contrary. The mistake is in confusing the great deal of knowledge that we have of personal identity, including perceptual knowledge, with implicit grasp of the application conditions of the concept personal identity.
Part of the impetus for Johnston’s criticism of the view that thought experimentation yields knowledge of conceptual truths was work by Johnston’s other supervisor, David Lewis. In ‘General Semantics’ and ‘Languages and Language’, essays by Lewis that have since become classics in the philosophy of language, Lewis introduces the distinction between languages considered as abstract objects and languages as spoken by actual speech communities. So, on the one hand, one can conceive of a language, roughly, as a function from words to meanings, or, on the other, as the kind of thing which, for instance, Mark Johnston and I both speak. A question which arises, given this distinction, is what makes it the case that Johnston and I speak one of these abstract objects, rather than another. And basically, Johnston says, ‘it seemed to me that members of a speech community could satisfy the condition, say, of speaking English – or perhaps a range of languages, of which English was one precisification – without grasping the meanings that were the abstract assignments to the sentences in the language, understood as an abstract object… I think the whole necessary and sufficient thing was partly motivated by this failure to clearly distinguish the abstract object that is a language – the recursive characterisation of truth in a language, the assignment of truth-conditions individuating the language you’re speaking – from what it is to speak that language, which can be much less demanding than grasping the necessary and sufficient conditions for applications of the terms.’
Not that Johnston is, in general, a sceptic about the use of thought experiments in philosophical investigation, as he clarifies when I mention recent arguments claiming that their use relies on nothing more suspicious than our capacity to make counterfactual judgements (such as that, were Lizzy to step into the teletransporter, she would not survive). ‘I of course have a lot of respect for thought experiments’, Johnston says. ‘But the category of thought experiments is not a natural kind, in the sense that there is only one thing going on there. Some of it is counterfactual reasoning that’s pretty constrained by having a causal or explanatory model in mind. However, the empirical material suggests that the order in which the counterfactual speculations are requested can affect the confidence or the assignment of truth-value, which suggests that there are distracting contextual things guiding us in some of our looser counterfactual speculations. I’m sure that if we had a long conversation about the similarities between Hannibal and Eisenhower, we could get into the frame of mind where we might say “Hannibal would have used the atomic bomb in the attack on Rome”. There’s a lot of evidence that our intuitions, including counterfactual intuitions, are driven by adventitious factors like that. Respectable thought experiments are the ones strongly constrained by causal or explanatory modelling, as in the old-fashioned Lewisian analysis of counterfactuals. I’m a big fan of thought experiments, so long as they’re constrained in such ways.’
What about when we do try to apply a certain concept outside the range of cases in which we ordinarily use it, as in teletransporter cases? In cases where the generics we possess conflict, I ask, is there no fact of the matter about whether a term applies? Or is there just a fact of the matter that we can’t know? ‘For all I’ve said, there could be a fact of the matter that we don’t have access to,’ Johnston says. ‘So that’s the way I think about personal identity. I think that we don’t have theoretical insight into our essence; you’re not going to get an empirical discovery of what our essence is. There’s a kind of deep psychological anxiety that this provokes – we don’t really know what we are – that’s a characteristic feature of the human situation. But, like Kant, I think that there might be practical requirements to think of ourselves in a certain way, and that’s the route by which I would arrive at a full story about personal identity: we might be practically required to take ourselves to have a certain kind of nature.’
This is a conclusion that Johnston has recently been advocating in response to what he calls the ‘personite’ or ‘fellow travellers’ problem. The personite problem, which threatens to yield the quite radical conclusion that it is impossible for human beings to behave ethically, was my first introduction to Johnston: it’s, to use a technical term, a trip. The problem ostensibly arises for two popular views in metaphysics, which I will call plenitudinous perdurantism and plenitudinous essentialism. According to such views, there are a great number of very similar beings that exist in my immediate spatiotemporal vicinity. Perdurantists think that, just as persons are extended in space, they are also extended in time. Just as I am constituted, at a time, by suitably interrelated spatial parts (like my hands and head), I am constituted, atemporally, by suitably interrelated temporal parts: there’s the stage of me that exists now; the stage that will exist in precisely one second; and so on. Plenitudinous perdurantists, moreover, think that there’s an entity indiscernible from me for almost all of my life, but which ceases to exist just before I do; another entity which ceases to exist just before that; another entity that was indiscernible from me from the time that I was two until the time that I was eighteen, but only existed during that period; and so on. Essentialism can be thought of as similar, but defined along the modal, rather than temporal, dimension. The entities plenitudinous perdurantists say exist are ones that are otherwise just like me, but which differ in their temporal persistence conditions; according to plenitudinous essentialists, there are entities that are otherwise just like me, but which differ in their modal ones. For instance, while I could have been born several days later, there’s some entity coincident with me that couldn’t have been, just as I myself couldn’t have been born to different parents.
Versions of these views, crazy as they might initially seem, are quite widely held across analytic metaphysics. Indeed, they have at least a core in common sense. To take the modal case first, once it is granted that I have certain essential properties, it’s not clear, philosophers argue, how it can be denied that there are further entities otherwise identical to me, but which have slightly different ones. After all, there seems to be nothing very special about my essential properties, such as that of having been derived from a certain zygote, other than that they’re the ones essential to me. Similarly, in the temporal case, it’s not at all obvious what should be special about the fact that the person-stages which constitute me are interrelated in a certain way, other, again, than that they’re the ones which constitute me. It seems, as philosopher John Hawthorne writes, ‘better to be metaphysically even-handed than radically anthropocentric in one’s ontology’: if we’re already willing to say that things as gerrymandered from the perspective of physics as persons exist, it seems highly unmotivated to deny that personites – the entities described above – exist as well. The underlying commitment here seems to be to a rather minimal naturalism, crudely understood as the view that no physical objects of which we can have knowledge are radically discontinuous from those investigated by the sciences – not even us.
The trouble is that the following moral principle also seems true: if two beings are very alike, then both matter morally or neither does. This principle, as Johnston points out, is ‘internal to our ethical practice [and] connects something of profound practical importance – moral status – to a certain kind or degree of ontological indistiguishability. Something like this principle… has been behind the morally admirable, if shamefully belated, extension of the protected circle of those with a recognised moral status.’ And what could possibly be more similar to persons than personites? The crucial thing is that, once we are committed to the existence of personites, it seems that we are committed to their moral significance – not simply because of their intrinsic metaphysical makeup – ‘one cannot just look at the metaphysics, as it were cold, ie independently of our ethical practice, and see what really matters’, Johnston says – but in virtue of one of our most cherished ethical principles. So if personites exist, they matter. And if personites matter, Johnston argues, this grounds a moral and prudential disaster:
We are then ethically required to be torpid, ie to organise our lives around the least possible amount of physical and/or psychological change, for otherwise we cause a vast multitude of our fellow travellers to cease to exist; to be feckless, for all forms of prudential self-sacrifice involve imposing costs on a vast multitude of fellow travellers without their consent or compensation; to be cold to the needs of others, for all forms of self-sacrifice, period, involve imposing costs on a vast multitude of fellow travellers without their consent or compensation; and to be rootless, for all forms of making demanding commitments to others, most notably, promising, impose costs on a vast multitude of fellow travellers who did not exist when the commitment was made.
These conclusions are, to put it mildly, very uncomfortable, which makes one feel certain that the problem here must be a sceptical one. Who could seriously believe that we are, in Johnston’s provocative phrase, morally otiose? Surely the only question can be of disarming his argument that we are, not of accepting its conclusion. But the naturalism relied on as a premise seems as if it would be an unacceptably high cost to pay. So perhaps, I suggest to Johnston, we should simply deny that personites really are relevantly similar to persons. Why not treat it as merely another surprising consequence of scientific investigation that only entities with certain persistence conditions matter? ‘That sounds to me like this’, Johnston says. ‘Oh, it’s just a surprising aspect of naturalism that white males in certain cultural circles are all that really matters. It’s a form of argument that advanced societies, if there are any, have come to dislike, because it seems to make a matter of fundamental moral importance – having moral status – turn on morally irrelevant differences.’ It sounds, he says, likely merely ‘projecting our preferred scheme into nature, in the same way that old white codgers (like me) might trumpet their alleged moral superiority by saying, “it just turns out that we’re better and count for more!”. Given reductive naturalism about personal identity, defending the privileged moral status of persons, privileged with respect to their fellow travellers, is uncomfortably like that.’
How, then, about the so-called ‘brutalist’ move of denying that the other entities are really there? This time, let the surprising consequence of naturalism be that only beings with certain persistence conditions exist all. ‘So I would distinguish’, Johnston says, ‘between a brute fact and a bare fact. A brute fact has no further explanation of its holding, but which can serve to explain other things. A bare fact is some fact that does not, as it were, connect with either the beginning, the middle or the end of some explanatory picture of the world – it is a fact that just floats free and is there very helpfully to support our practices in just the way we need. Brutalists are actually invoking bare facts, I think. And about those bare supposed facts, i.e. that only minded continuants of our sort exist, I’d like to know, oh, given the actual cognitive psychology of human development, and our evolutionary history, what the epistemic route is by which we got onto the privileged facts – the one we’ve organised our practice around, the only fact in the vicinity – as opposed to all these other apparent facts that look perfectly good. And of course we could, as far as I can tell, have evolved in such a way that we cared about other persistence conditions. Would that be an error?… So there’s an enormous amount of epistemic self-congratulation built into the bare fact version of the “brutalist” view, without any good naturalistic explanation of how we got into the privileged epistemic condition.’
Okay, so maybe we should go the route of the moderate philosophical sceptic – deny that philosophy has the power to so radically unseat our pre-theoretical convictions? That won’t work either, unfortunately. ‘Philosophy’s power is to deepen understanding’, Johnston says. ‘In this case we are deepening our understanding of an empirical hypothesis, naturalism, by looking to its consequences. Moreover, there is no a priori guarantee that our practical life is workable. Obviously there are tragic things one could find out that would show that you do not have a good way to go on. Suppose you discovered that every time you moved, a host of other beings were caused to go into excruciating pain. Could you just say, I can neglect their interests, since otherwise my life would be unworkable? My own view is that naturalism implies something in the same line of country. The a priori defence of going on in the same way is no better there.’
I raise another, more technical, response to the problem.* Johnston knocks it down, and, when it becomes clear that I have run out of arguments without having refuted him, seems rather disappointed. ‘I have about twelve objections that I knock on the head in one way or another’, he says. ‘But come on! There must be others.’ He proceeds to tell me the ethical view that he thinks does avoid the problem, consistently with naturalism: hedonistic utilitarianism. Hedonistic utilitarianism famously takes the only thing that matters morally to be the balance of pleasure and pain in the universe; it doesn’t care about any of the side-constraints that seem so essential to our ethical lives – but those are also what generate the personite problem. ‘So why not take it as a proof of that?’, Johnston asks rhetorically. ‘I just think it’s a mistaken account of the good. And kind of repellant – I mean, kind of evil. But I’m very judgemental. I also more fundamentally think, oh god, if that’s the good, we’re so disabled from getting at it. We’re not made to maximise pleasant states and minimise unpleasant ones. As Schopenhauer said, the bigger the window, the louder the noise. The evolved complexity of the central nervous system in human beings means that we find ourselves under constraints that happy animals aren’t under. For example the demand to live our lives, in some active conscious way, to do something worthwhile. Take the okapi – among the most beautiful of mammals, by the way. They’re made for the hedonistic life. Evolution has been a horrible waste in producing us if the good is pleasure…’
So much for naturalism and ethics, then? That’s Johnston’s conclusion: if human beings are not ontologically distinctive, there will be many things just like us, which we are obliged to care about if we care about ourselves. Naturalism rejects our distinctiveness; so it has to go. But is it epistemically permissible for us to give up belief in naturalism? In answering this, Johnston draws, surprisingly for an analytic metaphysician, on an idea from William James. ‘Suppose’, he tells me, ‘there’s an urgent practical question not settled by the evidence, on which you have to take a stand. Then I think it’s legitimate to take a stand on that question one way or another for practical reasons. And the practical reasons might be: look, I want to be thoroughly clearheaded in thinking through the consequences of my beliefs. If naturalism is the full story about our nature, then that would lead to an epistemic situation where I would have to give up on most of practical life. I’m practically required not to give up on most of practical life, therefore, in this urgent situation, I’m permitted to take a view of myself that would resolve that difficulty.’
The crucial thing, Johnston maintains, is that the truth of naturalism is not a settled question. ‘Naturalism is very good on its own terms’, he says, ‘but incomplete. And that already emerges from a proper consideration of the manifest qualities, and in particular, of our intentional relation to them, which seems to involve grasping some aspect of how they are in themselves. There is no good (reductive) naturalistic model for that. Moreover, with respect to the problem of content causation, I think this is something that people kind of knew all along: they kind of knew they were getting to an approximation which wasn’t that satisfactory, but it went on so long that people thought, well, the problem is so boring that let’s just treat it as solved.’ By the problem of content causation, Johnston means how it could be that we are moved by considerations ‘as such’ – that is, the problem of making sense of idioms like ‘appreciating the force of a consideration’. I might conclude that torture is ineffective in virtue of properly appreciating the fact that it rarely produces reliable information. Yet, Johnston claims, the notion of drawing a certain conclusion because of one’s grasp of certain facts is insolubly opaque by the lights of naturalism. So unless we are prepared ourselves to draw the conclusion that we are not moved by considerations as such, we have reason – independent of the personite problem – to regard naturalism as (at best) an open question.
There are obvious echoes, in Johnston’s argument for practical requirements on belief, of Kant, as Johnston freely points out. ‘Remember here Kant, or cartoon Kant’, he tells me. ‘“There are severe conceptual limitations on how much of reality we can understand, but we need to take a view about the larger structure of reality for practical purposes.” Kant’s own argument, I think, is that you need to do this, and so believe or hope certain things, otherwise you should conclude that ethics is bunk… This is connected with those passages in the Second Critique and of course in Kant’s Religion – a work that I greatly admire – in which he argues that part of being moral is recognising the importance of the principle of proportionality – that the virtuous deserve to be happy, to the degree that they are virtuous. Of course, he’s a realist, he thinks that the world as we see it is just not organised in such a way as to make that possible; indeed, he’s very worried that the predatory bad people will devour the good, that the good are unprotected. But without dramatising things, I think we can all agree that there is not much of a correlation between being virtuous and being happy. Aristotle had the pleasing view that there was, but we know much more about human history than he did, and we can say that his own historical circumstance was a case in which many very unvirtuous people, including Aristotle himself, were happy.’
But isn’t it just wishful thinking to hold out hope that the world vindicates proportionality – or that there aren’t hopelessly many beings intrinsically just like us? ‘Believing for practical reasons might have the first part of wishful thinking’, Johnston acknowledges, explaining old work of his on the topic. ‘The consequences of looking into the naturalistic void or the abyss are pretty bad – the abyss does look back, in Nietzsche’s terms. Maybe there’s a fear there, an anxiety that gets reduced by believing these things. But if what comes next is not a rationalisation, not a distortion of the empirical evidence in favour of the belief, but the kind of argument that Kant gives, and that James endorses, then it’s not wishful thinking in the bad sense – it’s hopeful thinking, as it might be.’ In fact, Johnston himself seems to hope that the kind of hopes required to successfully resolve the personite problem might bear as well on more Kantian worries about ‘the large-scale structural defects of human life’. According to the solution Johnston offers, we are ‘to think of ourselves as enduring substances, not exhausted by our spatiotemporal location’. ‘In order for ethics to be workable’, Johnston says, ‘and for us to self-consciously think through things in a philosophical way, it can’t be that we’re exhausted by our spatiotemporal footprint. That has to be an expression of what we are, rather than the whole of our constitutive nature.’ And, Johnston seems to conclude, if it is rational to hope that our constitutive nature extends beyond the spatiotemporal realm, then perhaps it is also rational to hope that our overall happiness does not reduce to our happiness in the here-and-now.
I don’t buy it myself. It seems to me that if none of the naturalistic solutions to the personite problem work, then Johnston has, in the first instance, developed a highly novel and powerful argument for the moral error theory, according which there are no facts about what we morally ought to do. I’m not sure Johnston would be surprised by this response. As he says, in a different connection, ‘I can understand the argument “all the forms of religious life that I’ve encountered are inauthentic, idolatrous, and repellant, so I don’t want to associate with these bullshit propositions”. For people with a certain temperament, it’s not going to be persuasive.’ Nevertheless, it’s very hard not to feel that Johnston’s problem makes vivid, to repeat Johnston’s phrase, naturalism’s lack of an a priori guarantee that our lives be practically workable: that, if naturalism is true, it really could turn out that our practices, unbeknownst to us, were – by the lights of our own ethical commitments, even if we refused to acknowledge them – enormously harmful. (As Johnston points out, non-reductive naturalism doesn’t really help. Non-reductive naturalists will maintain that even if persons are highly disjunctive at the level of physics, we are still not metaphysically gruesome, because there are other joints in reality. But then why shouldn’t personites be ontologically natural as well?)
Something else Johnston said seems relevant here too, that ‘a lot of people use a bad version of reflective equilibrium or Quine’s principle of the maxim of minimal mutilation. We’re habitual non-reductionists about personal identity and we think that we have something like libertarian free will. We think that we’re unique within our spatiotemporal envelope. Give up these things.’ What’s left? If naturalism lacks any guarantee of workability, it also lacks any kind of guarantee that we’ll know when the game is up – that we’ll be able to recognise the evidence for the unworkability of our ethical lives as soon as it comes in. Our picture of the world is not like a house of cards, where if the foundations are sufficiently undermined, the whole thing will come toppling down. Rather, as Johnston puts it, we could ‘pull the string out from near the centre of our web of belief’, even as we continued to believe that there’s been no major structural damage. So there is such a thing as ‘bad, or unreflective, reflective equilibrium’, which Johnston says he has seen in several published responses to the personite problem. An error theory of our belief that we are ethically distinctive seems in the offing too: since cognitive science suggests that we would be convinced that we were, even if we weren’t, we arguably stand on weak ground in resolutely continuing to believe that we are.
It’s perhaps not a coincidence that many of the philosophers most strenuously opposed to metaphysics – in particular, ordinary language philosophers – seemed complacent about such possibilities: one reason you might oppose revolutionary metaphysics is that you don’t see how there could be a revolution. Much of Johnston’s work seems to me to reflect the joys and perils of proceeding under different assumptions. ‘I think philosophy is a form of life’, Johnston tells me. ‘It’s a form of life in which you try to develop a systematic vision that deepens your understanding of reality. Insight is the thing that I would emphasise. Saul Kripke’s work is, among other things, a paradigm of insight, as is shown by the fertility of his examples, the way they illuminate a whole domain.’ Some of the conclusions and insights of philosophical life might be vindicatory – indeed, for most of his career, Johnston defended the coherence of things being more or less how they seem. But, as in so much of the rest of life, there is only room for genuine vindication if one’s activity carries with it the possibility of genuine defeat.
*For philosophers: The objection was that, according to the stage theory, persons are stages, not continuants, so there is no multiplication of morally significant entities. The response was ‘that the stage theory reproduces the problem in terms of which of the future-directed counterpart relations is morally significant. I just think there’s an isomorphism.’ (And when Johnston talked to Ted Sider, a leading advocate of stage theory, he ‘seemed to agree’.) Presumably the same response, if it applies, also applies to solving the modal version of the problem by appeal to counterpart theory.