For this year’s London Lecture Series we have decided to focus on metaphysics. We’re interpreting this widely, including anything that bears on basic questions of existence and/or fundamentality.

All the lectures start at 5.45 in 14 Gordon Square, London WC1H 0AR.  The talks last an hour, followed by a short break and half an hour of questions.  The lectures are free, there are no tickets, and no reservations can be taken. You are advised to arrive early to be sure of a seat, as fire regulations mean that when the hall is full we cannot let anyone else in.  All the lectures will appear on our YouTube channel.



14th – JONATHAN SCHAFFER, Beyond Fundamentality

I articulate a conception of metaphysics built to explain how and why things exist. Explanation generally requires a three-part structure of (1) starting conditions that are the source of what is to be explained, (2) concluding results to be explained, and (3) connecting links from the source to the results. So I articulate a view of the structure of reality involving (1) ultimate grounds as the starting conditions (this might be something like: the quantum mechanical state of the whole cosmos), (2) derivative states as the concluding results to be explained (these might include various chemical, biological, psychological and other “higher level” states), and (3) root principles as the connecting links (these might include principles codifying the ways in which the physical grounds the chemical). The resulting picture not only goes beyond merely listing what exists, but it also goes beyond the simple division between the fundamental and the derivative, in order to explain the structure of reality.

21st – NAOMI THOMPSON, Fictionalism about Grounding

Many philosophers have recently begun to talk about an explanatory notion of metaphysical dependence called grounding. Most discussants of grounding think that grounding talk is useful, intelligible, and accurately describes metaphysical reality. Call them realists about grounding. Some dissenters reject grounding talk on the grounds that it is unintelligible, or unmotivated. They would prefer to eliminate grounding talk from philosophy, so we can call them eliminitivists about grounding. This paper outlines a new position in the debate about grounding, defending the view that grounding talk is (or at least can be) intelligible and useful. Grounding talk does not, however, provide a literal and veridical description of mind-independent metaphysical reality. The fictionalist account I develop here is a form of (non-eliminative) irrealism about grounding, which treads a path between realism and eliminativism.




4th – STEWART SHAPIRO, Potential Infinity: A Modal Account

Beginning with Aristotle, almost every major philosopher and mathematician before the nineteenth century rejected the notion of the actual infinite. They all argued that the only sensible notion is that of potential infinity. The list includes some of the greatest mathematical minds ever. Due to Georg Cantor’s influence, the situation is almost the opposite nowadays (with some intuitionists as notable exceptions). The received view is that the notion of a merely potential infinity is dubious: it can only be understood made sense if there is an actual infinity that underlies it. After a sketch of some of the history, our aim to analyze the notion of potential infinity, in modal terms, and to assess its scientific merits. This leads to a number of more specific questions. Perhaps the most pressing of these is whether the conception of potential infinity can be explicated in a way that is both interesting and substantially different from the now-dominant conception of actual infinity. One might suspect that, when metaphors and loose talk give way to precise definitions, the apparent differences will evaporate. As we will explain, however, a number of differences still remain. Some of the most interesting and surprising differences concern consequences that one.s conception of infinity has for higher-order logic. Another important question concerns the relation between potential infinity and mathematical intuitionism. We show that potential infinity is not  inextricably tied to intuitionistic logic. There are interesting explications of potential infinity that underwrite classical logic, while still differing in important ways from actual in.nity. However, we also find that on some more stringent explications, potential infinity does indeed lead to intuitionistic logic.

11th – BOB HALE, The Basis of Necessity and Possibility

What is the source, or basis, of absolute – as opposed to merely relative alethic or epistemic – necessity and possibility? After briefly sketching my reasons for dissatisfaction with the main attempts to provide a reductive explanation of necessity and possibility – in terms of meanings or conventions, and in terms of possible worlds and combinatorialism, I outline what seems to me a better theory, which takes necessities to have their basis in the nature or essence of things, and discuss some of the question and problems such a theory must deal with, if it is to provide a credible alternative.

18th – AMIE THOMASSON, Easy Ontology and the Work of Metaphysics

Over the past sixty years or so, metaphysics has abounded with existence questions: Do numbers exist? Do people exist? Do ordinary objects exist? Do properties exist? In Ontology Made Easy, however, I argued that such questions are not proper subjects for deep metaphysical inquiry, since they can be answered straightforwardly, using nothing more mysterious than conceptual and (sometimes) empirical work. Here I aim to clarify the easy approach to ontology and its virtues over ‘mainstream metaphysics’, and to address some difficult questions that remain. First, how, on this model, does metaphysics compare to science? If the sciences can make good use of theoretic virtues in coming to the best theory, can’t metaphysics do the same? Second, if ontology is indeed easy, does any legitimate work remain for metaphysics to do? Should metaphysics turn to investigate issues like truthmaking or grounding instead of existence? Or should metaphysics be given up, or reconceived more radically?

25th – ELSELIJN KINGMA, The Metaphysics of Pregnancy




2nd – TIMOTHY WILLIAMSON, Spaces of Possibility 

Modal metaphysics asks not just how things are but how they could have been otherwise. Empiricists have regarded it with suspicion, as beyond the reach of respectable science, because observation tells us how things are but (allegedly) not how they could have been otherwise. In this lecture, I will argue that such criticisms are ill-founded, and that modal metaphysics is continuous with modal science, which investigates how things could have been otherwise, for example by studying phase spaces: abstract mathematical representations of the possible states of a physical system.




20th – TIM BUTTON, I disappear.

There is are ways of thinking about the self—the subject of experience—which push us towards saying daft things, such as “I am the tree of life, and all living things are my branches”. Since we don’t want to make such daft claims, we need to drop the ways of thinking that push us towards them. Drawing on Wittgenstein’s Blue Books, I shall sketch how.

27th – SALLY HASLANGER, What is a Social Structure?

Social structures play an important role in explaining a wide variety of phenomena.  Nevertheless, due to background commitments to methodological individualism and (in some cases) a kind of psychologism, social ontologists have treated social structures as if they are reducible to or fully explicable in terms of the psychology and behavior of individuals.  I argue that this is a mistake. We would do well to attend to material and cultural dimensions of social structures in order to fully realize their explanatory potential.


3rd – KATHERINE HAWLEY, What are Social Groups?

Abstract: Committees, crowds, and ceilidhbands are made up of people.  But how?  What is the metaphysical relation which connects member to group?  Perhaps social groups are sets, perhaps they are abstract structures, perhaps they are irreducibly plural.  I will explore these options, before arguing that social groups are large, scattered, material objects.

10th – PENELOPE MACKIE, Compatibilism, Indeterminism, and Chance

Many contemporary compatibilists about free will and determinism are agnostic about whether determinism is true, yet do not doubt that we have free will. They are thus committed to the thesis that free will is compatible with both determinism and indeterminism. This paper explores the prospects for this version of compatibilism, including its response to the argument (traditionally employed against incompatibilist accounts of free will) that indeterminism would introduce an element of luck or chance that is inimical to free will and moral responsibility.

17th – SUKI FINN, Nonexistence

Are there things that do not exist, for example, Santa Claus and square circles? Would such nonexistent things in some way have to exist in order for us to make sense of them, speak truthfully of them, and disagree meaningfully about them? And when we disagree about the existence of such things, are our disagreements merely about the language we are using? In this talk I will explore these fundamental questions in metaphysics by looking to the philosophy of language and logic, in order to motivate a view that is able to accommodate nonexistence.

24th – JESSICA LEECH, Essence and necessity: a marriage made in heaven, or time for divorce?

Philosophers have traditionally closely associated the essence of a thing – its nature, or what it is to be that thing – with the necessities for that thing – how it must be, and thus also, how it could and couldn’t be. Different philosophers have taken this association in different directions. For some time, the received wisdom was that essence should be defined in terms of necessity: the essence of a thing is to be identified with how it must be, its necessities. This direction of explanation was challenged in the late twentieth century, most notably by Kit Fine. Fine and others have argued that in fact we should understand the nature of necessity in terms of essence. The essence of a thing should be taken to be primitive, and we understand its necessities in particular, and the nature of necessity in general, in terms of that essence. In my talk, I will question whether we should accept this close association between essence and necessity, in either direction. I’ll discuss what role these key notions – essence and necessity – can reasonably be thought to contribute to our metaphysical understanding of the world. I’ll argue that, given these roles, there’s no good reason to think that we should define one in terms of the other. Indeed, I’ll suggest that trouble ensues if we try to do so. Rather, we should take each on its own, independent, terms.


3rd – KATHRIN KOSLICKI, Towards a Distinctively Hylomorphic Solution to the Grounding Problem

Concrete particular objects (e.g., living organisms) figure saliently in our everyday experience as well as our in our scientific theorizing about the world. A hylomorphic analysis of concrete particular objects holds that these entities are, in some sense, compounds of matter (hûlç) and form (morphç or eidos). The Grounding Problem challenges those who believe that a single region of spacetime can be occupied by more than one object (e.g., a statue and the clay which constitutes it) to explain how numerically distinct spatiotemporally coincident objects can differ with respect to their modal profile (e.g., the clay’s ability to survive being squashed, as compared to the statue’s inability to do so). In this paper, I argue that a hylomorphic analysis of concrete particular objects, in conjunction with a non-modal conception of essence, has resources which other competing analyses lack to offer a distinctive solution to the Grounding Problem.

10th – ALEXANDER BIRD, The Structure and the Necessity of the Natural Laws

What is the structure of the natural laws?  How do the less fundamental laws relate to the more fundamental laws?  We find that many of the non-fundamental laws turn out to be metaphysically necessary.  More generally this means that in many respects the world could not have been similar to the way it actually is, differing only to a small degree.  Other possible worlds are very different.

17th – PENELOPE RUSH, Optimistic Metaphysics

For Gödel, the idea that there really is an objective independent mathematical realm gives an optimism, inspiring continued endeavour to discover the truth – the way things really are. On the other hand, a Hilbertain faith in the formal system(s) of mathematics to answer any ‘natural’ mathematical question we might wonder about, is also a kind of optimism. In general, if truth is constrained by what we can (even if just in principle, or in Utopic scenarios) know, we can hope that knowledge will increasingly circumscribe truth. But if truth is in principle independent of (even ideal) knowledge, we can hope that what we know might somehow, sometimes constitute a genuine discovery or insight into the ways things independently are. Both versions of ‘optimism’ are optimistic in their own way, and both can also be characterised as expressing a certain sort of humility. In this talk I’ll look at a few different areas of enquiry, including logic, mathematics and physics, using the idea of an ‘optimistic metaphysics’ to compare possible metaphysics for each of these area – in particular exploring which of the two different notions of optimism (or degrees of such) might best be suited to each area, and in that case, the extent to which the resultant metaphysics is best described as ‘optimistic’ at all.

A book bringing all the talks together will be published by the Cambridge University Press.