# Why Metaphysical Debates Never End

Speaker: Amie L. Thomasson
Course: Making Metaphysics Functional
Watch: https://ergo.org/videos/amie-l-thomasson-why-metaphysical-debates-never-end
Transcript: https://ergo.org/videos/amie-l-thomasson-why-metaphysical-debates-never-end/transcript/
YouTube: https://www.youtube.com/watch?v=YF-yDah-ja4

When quoting, name the speaker and link to the watch URL.

In this lecture, Amie L. Thomasson examines how metaphysics came to be understood as the study of ultimate reality and why that conception has led the discipline into deep trouble. She begins with the origins of the term itself, tracing how philosophy and science were once unified before the sciences broke away, leaving philosophers in crisis over what remained for them to study. Thomasson surveys the early 20th century rejection of metaphysics and its later revival through Quine's influence, then identifies what she calls "symptoms of dysfunction": a massive proliferation of competing views with no agreement about what would settle debates, leading to widespread skepticism even among practitioners. She diagnoses the core error as "functional monism," the assumption that all of the terms of interest in metaphysics serve the same purpose. She also critiques several prominent approaches including the neo-Quinean, structural, truthmaker, and grounding frameworks. The lecture concludes by introducing functional pluralism and conceptual engineering as tools that can resolve longstanding problems while preserving valuable work from the history of philosophy.

## Origins and Etymology of Metaphysics

Welcome to lecture one, How the Traditional Conception of Metaphysics Goes Wrong. So where did metaphysics come from? The term metaphysics, to name a work of Aristotle's, but it's not a term that Aristotle himself used. Instead, it's a term that was added to his works by an editor who was putting together all of the works that Aristotle left behind in the first century BCE.

And the editors found this bunch of works that came after the *Physics*, and so he called it Ta Meta ta Physika, meaning in Greek, meta, above or beyond physics, but just meaning it's the work that came after the one called the *Physics*, not that it's above and beyond physics as we know it now. The set of works that came after the *Physics* in Aristotle was 14 books that were supposed to be read after reading the *Physics*. And in those books, Aristotle discusses questions of what he called first philosophy. He asked questions about first causes, about things that do not change. And so this set the scene for later work in what came to be called metaphysics.

## Metaphysics as the Study of Ultimate Reality

Now, the idea of metaphysics broadened over time, so that nowadays, if you pick up pretty much any introductory anthology on the topic, it'll start by saying something like this, that metaphysics is the study of ultimate reality. Metaphysician Jonathan Lowe wrote, quote, "The central concern of metaphysics is with the fundamental structure of reality as a whole." Peter van Inwagen wrote, quote, "When I was introduced to metaphysics as an undergraduate, I was given the following definition: Metaphysics is the study of ultimate reality. This still seems to me to be the best definition of metaphysics that I've seen."

This is the standard self-conception among metaphysicians of what they're doing. That they're engaged in a project that's aiming to discover some kinds of very basic, general, or fundamental facts about the world. These are often thought to include questions about what exists, the existence of God or free will, or even recently, questions about the existence of persons or tables and chairs have been called into question.

These include questions about the natures of things. What is the nature of a person? What is it to be free, for example? Or questions about fundamental facts of the world and how they can ground or be the basis for other kinds of facts and things that we seem to observe in the world, like tables and chairs and classrooms and legislatures. That's the standard conception.

## When Philosophy and Science Were One

Now, if we went back to the history of metaphysics, again, it started a long time before this conception that I'm describing to you now. If you look back in the history of philosophy, when it began in the Western tradition in ancient Greece, and all the way up through what gets called the modern period, there really wasn't a clear separation between philosophy and the sciences. As you may have heard, the word philosophy just derives from the Greek terms philos, love, and sophia, wisdom. So it's a general love of wisdom, and if you look back at the history of philosophy, that's where it starts.

In the pre-Socratic philosophers, that's those ancient Greek philosophers who came before Socrates, hence pre-Socratic, they were interested in all sorts of questions, many of which would now be parts of physics, what we call cosmological questions. They saw the world as a kind of intelligible, ordered arrangement and thought we could come to understand it, and that was actually a kind of new idea. So you saw theories among them, like Thales, who said, "Well, look, maybe everything comes from water," or Diogenes, who thought that everything's just alterations of air.

If you look at the ancient Greek philosophers also, you'll see they had interest in all sorts of wisdom, in many different things. So Pythagoras, philosopher, also you've probably known about through mathematics, through the Pythagorean theorem. Thales was super interested in geometry and made advances in that. Anaximander worked in astronomy. Aristotle was really interested in biology. So they were interested in all sorts of stuff.

And this didn't really change even in the period that we think of as the period of modern philosophy, which is from the 17th and 18th centuries. So Descartes, René Descartes, the French philosopher, again, you may have heard of him first through the Cartesian coordinate system that's used in mathematics. He was also interested in metaphysics, but beyond that, in physics itself. Bishop George Berkeley made important advances in optics. Kant was interested in geology and astronomy, as well as philosophy.

As the American philosopher, we'll talk more about him later, Willard Van Orman Quine, he was an American philosopher, second half of the 20th century mainly. He wrote, "All these luminaries, including Aristotle, Plato, Descartes, Leibniz, Locke, Berkeley, Hume, Kant, and others whom we revere as great philosophers, were scientists in search of an organized conception of reality." So that was all cool, that was all good, until, you'll have guessed where this is going.

## Science Breaks Away and Philosophy's Crisis

Around the 17th to 19th centuries, what we now think of as the natural sciences began to separate themselves from philosophy. First, in the 17th century, we see fields like physics and chemistry begin to separate themselves from other inquiries and become self-conscious about their methodology. You see the development of the scientific method. This kind of separation kept going on, right up, it wasn't really until the end of the 19th and beginning of the 20th century that psychology began to separate itself from philosophy.

Now this, of course, as the sciences separated, left a huge gaping question that philosophers were very much aware of. What's left for philosophy to do? And especially for that branch of philosophy that thinks of itself explicitly as trying to make deep worldly discoveries about what the world is like and what its nature is, metaphysics. Concerns about whether we can distinguish the work of philosophy from the work of the sciences and whether there's anything left. These were around already in the 19th century.

In fact, one early answer to what's distinctive about philosophy, you can see it in some of John Stuart Mill's works, as well as others whose works haven't really passed the test of time, was the idea that philosophy studies inner mental phenomena while the natural sciences study external physical phenomena. But of course, once psychology broke off as its own science, that view of philosophy couldn't last. The concern that there's nothing left for philosophy to do has then persisted, and maybe some of you have come to these lectures with that kind of concern.

One recent way of putting this idea forward was in a book by Stephen Hawking and Leonard Mlodinow from 2012, and they put things in really strong terms, so I'll read you the quote. They say, "People have always asked a multitude of questions. How can we understand the world in which we find ourselves? How does the universe behave? What is the nature of reality? Where did all this come from? Traditionally, these are questions for philosophy. But philosophy is dead. Philosophy has not kept up with modern developments in science, particularly physics. Scientists have become the bearers of the torch of discovery in our quest for knowledge."

That's throwing down the gauntlet in very clear terms, of course, from a physicist. If there is a rivalry between the work of philosophy broadly or metaphysics more particularly, and the natural sciences, it seems like a rivalry that metaphysics is bound to lose. The sciences have very good credentials and very good methodology for their claims to knowledge, and scientific advances have led to technological advances and medical advances that we rely on. In a sense, we can know these work. But the challenge, then, is to say what work, if any, remains for metaphysics especially and philosophy more broadly, and I'll come back to that in the final lecture.

## Early 20th Century Rejection of Metaphysics

Now, as I was saying, the philosophers in the end of the 19th century were very much aware of this problem, and by the start of the 20th century, there was a standard answer to this. A lot of philosophers during that time, first half of the 20th century, really became suspicious of work in traditional metaphysics. And they thought that a lot of the questions of metaphysics, traditional metaphysics, were disguised nonsense or could be avoided or easily dissolved. Now, if they can be shown to be nonsense or resolved or dissolved by attention to how the language governing these problems works, then that's okay. That can linger. But anything else, certainly the logical positivists rejected as just nonsense.

So three of the major schools in the first half of the 20th century in philosophy all roughly agreed on this, that the work of philosophy should be thought of not as engaging in deep discoveries about what exists or the nature of things. That's for the sciences. But rather, as conceptual or linguistic inquiries, that is, trying to understand how our conceptual system or linguistic system works or maybe even how it can or should work.

So you see in the works of phenomenologists, for example, people like Edmund Husserl and Martin Heidegger in the beginning of the 20th century. Questions about what is needed in order to be able to experience a world, a world of tables and chairs and other people and morality and so on. What's needed to be able to experience that world at all? What kind of concepts do we need in our scheme?

Ordinary language philosophy, which was really dominant, especially in the UK in the middle of the 20th century, and led by figures like Wittgenstein. Again, you may have heard Wittgenstein talk about the need to free ourselves from linguistic confusions. On his model, philosophy is showing the fly the way out of the fly bottle, trying to dispel the kinds of confusions that lead to certain metaphysical questions. Others, like Gilbert Ryle or J.L. Austin or Peter Strawson, were interested in other questions about how ordinary language works. Ryle was interested in questions about how our mental concepts work. Strawson wanted to know what kinds of concepts are essential to any conceptual scheme, and so on.

Then there were the positivists, who I mentioned earlier, who thought of much prior metaphysical work as nonsense and thought that what was left for philosophy was works of clarification and analysis. That is, analysis of language. Distinguishing the meaningful from the nonsensical, which bits of language are meaningful and which are nonsensical. Stating what they called analytic truths. That is, truths that we can know about just by understanding the meanings of terms and by doing basic reasoning. And constructing new terms or concepts for use in the sciences.

So these are three really different philosophical traditions in a lot of ways, but they all agreed on this much, that the work of philosophy shouldn't be thought of in terms of traditional metaphysics as trying to discover some sort of deeper, hidden truths about what exists or what the world is like. They would've all been happy to leave that to the empirical sciences, but rather to do with linguistic or conceptual work. So that's where we were in the middle of the 20th century, with this widespread consensus that the work of philosophy should be thought of broadly in terms of linguistic or conceptual work.

## Quine's Influence and the Revival of Metaphysics

What happened? Well, one of the main things that happened was the work of American philosopher Willard Van Orman Quine. And Quine raised some very famous arguments that you can't distinguish what he called analytic from synthetic statements. That is, there's no way to distinguish claims that are true in virtue of meaning, which is what the positivists thought we could still do, from the empirical claims of the sciences. I won't get into the weeds of all that here, but that convinced many people, I think prematurely, that there wasn't a way to distinguish this work on understanding language and meanings from the empirical work of the sciences.

Besides that, there was a lot of, I think, restlessness among metaphysicians who really felt the traditional hankering to say something more. They would say things like, "Oh, look, talking about our language or concepts, that's just shallow. I don't care about how our language or concepts work. I care about what the world is like." And so they thought of Quine, I think in ways he wouldn't have endorsed, as giving them license to go back to doing metaphysics and thinking of it as part of the same project as science, and thereby, I think they hoped, as gaining some of the respectability of the sciences.

So that led to a kind of revival in metaphysics in the wake of positivism, which had really treated metaphysics as dead and as nonsense. And there's been a really serious revival of metaphysics in philosophy, I think especially American philosophy, but also other places in analytic philosophy over the last 75 years or so. First in people who took themselves to be following Quine's approach. Those would be called neo-Quineans. I'll talk about them. And then others who had dissatisfactions with that approach, but not with the very idea that we could do metaphysics and came up with different conceptions of what we're doing and how we can do it. So there's this problem with the rivalry with the sciences.

## Is Metaphysics More General Than Science?

What do we do about that? Well, the first standard answer that's usually given by metaphysicians in the last 75 years or so, and again, you'll see this if you look at any introductory book or anthology on metaphysics, is that, look, metaphysics isn't a rival to the sciences because it's more general. It's not just concerned with physical reality, but we also ask other questions. We ask about the nature of moral reality. What are moral obligations? What are moral facts or properties? Are there such things?

We ask about the nature of possibility. What are possibilities? Are there other possible worlds, for example? We ask questions about the existence of numbers or properties or freedom, all of these being things that scientists don't tend to focus on, certainly not in the physical and chemical sciences. So that's the standard answer, and I will come to problematize that, that metaphysics is more general. It's still asking questions about the world, but that are more general than you would get from physics, chemistry, biology, et cetera.

## Symptoms of Dysfunction in Metaphysics

Metaphysics has gone on for the last 75 years or so, happily pursuing these questions. Now, I want to say, as someone who's been in the field for a while, that if you look at the work of the metaphysical revival, that is from 1950 onwards, with a neutral eye, not as a committed practitioner, you can see symptoms of dysfunction everywhere you go.

One is there's been this huge proliferation of views in metaphysics. We like to think that in the sciences, we get a gradual convergence on the truth. That's not to say that they have all converged, and of course, at some really difficult theoretic ends of science, like quantum mechanics, we don't have convergence. That's where it gets closest to philosophy. But by and large, we tend to get convergence on scientific theses over time. In metaphysics, by contrast, the longer we go on, the more and more we get a proliferation of views, more and more wildly different and often counterintuitive views.

A lot of people think that one of the jobs of metaphysics is to say what exists. They pull that out of Quine. And we get a divergence of views about what exists also. There have been people in the last 50 years who have denied the existence even of ordinary objects like tables and chairs and said there are no such things. There's just collections of particles arranged table-wise or chair-wise, or who've denied the existence of persons, for example. So even what seems most obvious, people deny.

On less obvious things like properties, there's a huge range of views. Do we want to say there are properties like redness that are the same in each red apple, or are there just individual rednesses in each apple? Or is this talk of properties somehow confused and misleading to begin with? So we get this huge proliferation of views with no real agreement about what would settle it. Where we have competing scientific theories, there are typically agreements, at least about what kind of fossil discovery or experiment in the particle accelerator or whatever would help settle the issue. Not so in metaphysics.

Now, one result of this massive proliferation of views has been a kind of skepticism, even among metaphysicians and other philosophers, about whether we can really know anything in metaphysics. So Karen Bennett, for example, develops what she calls an epistemicist's view, saying that really there's little justification for believing either side of many traditional debates in metaphysics. Others, like Robert Nozick and Edouard Machery, have denied that we can know about what's possible or what's necessary in ways that are important if you want to discover the natures of things in metaphysics and said, well, we should just be skeptical about our ability to know the answers to any of these questions.

These both tie up with a third problem, which I've alluded to already, what I would call epistemological mystery. Epistemology is just the study of knowledge, the theory of knowledge. So how can we know these claims in metaphysics? How can we hope to settle these debates? In most cases, as most of the disputants in these metaphysical debates will tell you, the competing theories are empirically equivalent. So if you are arguing with someone who says there's no chairs, and you say, "Well, sure there are. Here's one right now, I see it, I feel it," they'll say, "No, that doesn't count. I can account for that experience just by saying what you're seeing is particles arranged chair-wise." There's no empirical difference in these views.

Similarly, there's no empirical difference and no test you could run to discover whether or not the redness in the two apples is one property in two places, or is two different particularized properties, which people call tropes, and so on. Now, a lot of metaphysicians will say, "Well, look, we can appeal to theoretic virtues like parsimony in terms of what sort of objects we are saying exist, which has the sparest ontology," as they say. Or explanatory power and so on, appeals to these explanatory and other theoretic virtues.

But those are problematic too, because often you get two different theories that are empirically equivalent and they just trade off different theoretic virtues. So one will say there's fewer objects, and the other will give you what they'll call more explanatory power, and it's not at all clear how to weigh them up, or whether these so-called theoretic virtues are really things that will tell us which one is more likely to be true, or just mark which theories are easier for us, limited human beings, to understand and to use.

## Functional Monism as the Core Error

What I'm going to do next is to try to give a unified diagnosis of where all these major ways of approaching metaphysics, especially those that have arisen in the second half of the 20th century and beyond, have gone wrong. The proliferation of views, the skepticism, and the epistemological mystery, I think, are all symptoms of dysfunction, but that's not a diagnosis of why they've gone wrong. And I'm going to diagnose them as all making the same type of error.

And that is the error that I'll call functional monism. And that's the error of assuming that all of the different kinds of discourse that are used in asking the questions of metaphysics and used in our daily lives, discourse about morality, about possibility, about properties, about numbers, as well as about tables and chairs, assuming that they all serve the same type of function. And that's where I think we go wrong. And I think the cure is to have a better attention to what the different functions are of these different kinds of vocabulary.

## Critique of the Neo-Quinean Approach

Let me start, and I'll spend most of my time now talking about the explanatory conception, because this was really the dominant one that led to the rebirth of metaphysics after Quine. And as I mentioned, most metaphysicians working in this way will trace their views to Quine. Although Quine really, I think, wouldn't have fully approved of this metaphysical project. He was at heart a pragmatist. But we'll leave the historical Quine off the page here and talk about these metaphysicians.

Here's their conception of what we can do in metaphysics that came out of Quine's paper on what there is in the early 1950s. And the idea was this. Look, at least one of the big tasks of metaphysics is to answer the question, what is there? Quine spoke of that as doing ontology. Ontology is offering a theory of what exists. How do we answer that? Quine said, "Look, we start from the sciences. We want to figure out which is our best total explanatory scientific theory." Then state it carefully, preferably in terms of first-order logic. Figure out what sorts of entities, as Quine put it, you have to quantify over, or you might say more informally, you have to say there are, in order for these statements to be true. Then say there are those things. We're cool.

One of the motivations for taking on this kind of neo-Quinean approach to metaphysics was that it seemed to lend the work of metaphysics or of ontology a kind of respectability like the sciences. Now, this theory was developed in two different ways. One was to say, look, what we want is for the entities we say there are to add explanatory power to our theories. They've got to be able to explain something to earn their keep in our theories. And so even Quine himself goes through and talks about things like meanings and properties and says, "Look, these don't add any explanatory power to our theories. We can't explain anything by saying there are these." And he spoke of them as occult entities, like properties or meanings. They don't serve as causal explainers.

Now, I actually think Quine was onto something there, that they don't. Think for a minute about our talk of meanings. Red means the same as rot in German. They have the same meaning. Now suppose you try to say what explains that rot can be translated well as red, or that they are synonymous. Oh, it's because they have the same meaning. You can say that, but it's kind of empty words. Instead, I think we introduce terms like meaning as a kind of nominalization out of that. When are we entitled to say this word means the same as that? And then from that, we can say, oh, then they have the same meaning. But then meanings aren't posits like black holes or microbes or something that are supposed to causally explain something. They're just a manner of speaking that we can derive from saying red means the same as rot or maybe means the same as possibly or whatever you want to do. You can do it in one language or different languages.

Similarly, if you've got your two apples, a traditional metaphysician might want to say, what explains why these apples are both red, have this exact similarity? And a traditional metaphysical explanation, so-called explanation, will be, well, it was because they have the same property. Or if you really want to get old school metaphysical, you could say because they participate in the same Platonic form of redness, and go back to Plato. But again, I think property talk is just derived as a kind of nominalization out of saying this apple is red, so this apple has the property of redness. That apple is red. That apple has the property of redness. So there's a property of redness both have in common.

So in both these cases, talk of meanings and talk of properties, these aren't things posited to explain something. Instead, they are introducing new noun terms that we can use in generalizing in certain ways. But if we try to explain in those terms, we're not going to get anything other than a dormitive virtue explanation. You might remember the idea of a dormitive virtue explanation if you've read Moliere. He introduced this term, in his play, *The Imaginary Invalid*. He imagines this doctor being asked, "Why is it that poppies make us sleepy?" And the doctor says, rather pretentiously, "Oh, it is because they have the dormitive virtue." But the joke of it is that the dormitive virtue, that's just a fancy way of saying they make us sleepy. It doesn't explain anything.

So similarly, I think terms for meanings and properties, they can't give us any explanations that aren't just dormitive virtue explanations. In that, I think Quine was right. But does that mean that we have reason to say there aren't or aren't really properties or meanings? That's where I think it goes wrong. Do they contribute explanatory power? Be a universal across-the-board criterion for accepting or rejecting entities. Maybe it's great for figuring out whether you need to posit a new, say, fundamental particle or whether you need to posit two murderers at the crime scene rather than one. Say what else that would explain. But I don't think it's good as a criterion across the board.

Why? Because not all of our terms serve or are even supposed to serve to track something that would explain causally something that we observe. Think again about property terms. I just said I don't think they can explain what we observe, but they do play an important role in being able to even state and formulate general questions and scientific theories and laws. So think yourself back to the beginning of the pandemic. Lots of questions arose. You wanted to ask generalized questions like what properties is it that those patients who are severely affected by COVID-19 have in common that others don't, those who recover from it don't? We need property talk to be able to even ask that question and answer it.

We also need property talk to be able to talk about the property of, say, having a certain temperature or a certain pressure and so on, to be able to even formulate scientific laws like the ideal gas laws that tell you about the relationship between the pressure, volume, and temperature of any sample of gas. So this property talk plays a really important role in being able to form the generalizations we need to do science. But properties aren't posits like black holes or fundamental particles or microbes that are supposed to causally explain anything.

Similar things can be said about numbers. So the contemporary philosopher Steve Yablo has this neat argument showing that you have to have noun terms for numbers, so you can talk about the number three and the number five, not just five apples, in order to be able to state certain scientific laws in finite form, that otherwise it would take an infinite series of infinitely long statements to try to state the laws. So noun terms for properties and numbers are really important in formulating scientific theories. But these noun terms aren't trying to posit or describe explainers. And so the failure of properties or numbers or meanings to contribute explanatory power in this sense gives us really no reason to deny that there are such things. That's just a mistake. They're not supposed to posit explainers.

More than that, we can say not just do some of the noun terms in our scientific theories do things other than try to posit explainers. We could also say, yeah, science is great, but that's not all we do in human life. We're not always formulating scientific theories. We use language also in formulating our laws of state, like what laws are we going to live under, in writing out legal judgments, in criticizing works of art, in creating works of art, in arguing with our friends, in offering moral discussions, and so on. We have so many uses for language beyond just scientific discourse, and that they're not involved in that project doesn't mean they're worthless, so to just be thrown out. Instead, they have their own functions.

Legal discourse has its own functions of trying to establish certain standards under which we are to live together, and standards also for assessing who has and hasn't broken laws and who can punish them and how and so on. So a lot of these kinds of terms that enter into our legal discourse, our moral discourse, and so on, they're not even trying to formulate explanatory scientific theories. And so the failures of our terms for moral properties, for legal standing, et cetera, it would be ridiculous to reject them for not positing things that add explanatory power to our theories. That's not what they're up to. That would be like evaluating all artifacts from knives to vases to hairdryers on the basis of how well they cut steak. It's great in one instance, but it's just a mistake in the others.

So the explanatory power criterion and the whole approach to metaphysics that sees what we should be doing as figuring out what entities we have to say exist in order to make true our best explanatory scientific theories, I think is a mistake. It's a mistake based on artificially generalizing what's correct about one area of discourse across all areas of discourse whatsoever. And this is where we get back to the generality problem. Because metaphysics pretends to, purports to, talk about all these kinds of areas of discourse, about morality, about possibility, about the law, whatever. But then to combine this generality with a really narrow understanding of function that, in this case, has come from the functions of certain terms that posit would-be explainers in our scientific theories.

So I think what we need to do is not to reject the entities, to deny that there are possibilities or meanings or properties or numbers, but rather reject the criterion as an across-the-board criterion, and reject this kind of scientistic conception of metaphysics that has come with it. If metaphysics is really going to be completely general and address questions about morality, modality, law, art, whatever, we have to take all these different kinds and functions of discourse into account and ask questions about the functions of the discourse.

## Critique of the Structural Conception

That's the neo-Quinean conception of metaphysics, roughly. Now, questions about what we can do in metaphysics and how we can do it started to come to discussion again right at the beginning of the 21st century. People started to raise these questions again, I was one of them, about what metaphysics can do and how we can do it. And various kinds of dissatisfaction arose with the neo-Quinean approach. And in that wake, a lot of serious metaphysicians, those who wanted to continue something like this program, came up with other ways of thinking of it.

So I'll just talk more briefly about those conceptions, so you know they're out there, and I'll also try to make the case, again very briefly, that they all suffer from the same mistake. One of the alternative views of what metaphysics could do, and this was developed by the philosopher Ted Sider in his 2011 book, I call the structural conception. He thinks that the Quineans are all wrong in thinking that metaphysics is about answering the question, what exists or what is there? He spins it the following way instead. He says, "Now look, the metaphysical question is fundamentally not about what there is, but about structure, about the structure of the world." And he thinks of metaphysics as aiming to discover the fundamental structure of the world.

Again, this might sound like it has a rivalry with the sciences. Sider presents this in terms of trying to figure out which of our terms, as he puts it, carve the world at its joints, rather than just being arbitrary or gerrymandered kinds of ways of talking about the world, like electron or cow as a term, one he considers. But like the other metaphysicians, he thinks of his work here as more general than what you can get if you're a physicist or a chemist and asking which, say, chemical kind terms carve the world at its joints. Because he also wants to ask these questions about, say, our logical terms like and, or, if then, do they carve the world at its joints? Moral terms, modal terms, which of these really carve the world at its joints?

And so again, he's making the general assumption that this is a good criterion to use in evaluating discourse of all kinds. We should always ask, do these carve the world at its joints or don't they? Do these terms track structure or don't they? But again, if we take seriously the idea that different terms might have different functions, and I'll come back in later lectures to talk about how we can make good on that idea, then the idea that, say, moral or modal terms should be carving the world at its joints is just wrong-headed from the beginning. We should just say, look, that's clearly not what they're even supposed to do, but that's no knock against these areas of discourse, no reason why they're worse than the discourse of physics.

## Critique of the Truthmaker Approach

Another really popular way of thinking about the work of metaphysics is in terms of what's been called truthmakers. The idea of a truthmaker is the idea of what it is in the world that makes our claims true. It's an idea that gets traced back to Wittgenstein's early work in the *Tractatus*, then it was made popular again in a paper by Barry Smith, Peter Simons, and Kevin Mulligan, and then really popularized in the work of philosophers like David Armstrong, Australian philosopher Ross Cameron, John Heil, in the last 30 years or so.

There's different versions of this project, but the idea is whenever we make a claim, it's appropriate to ask, what is it about the world that makes it true? In its strongest form, and this is a form developed by Ross Cameron, the idea is that what we should do in metaphysics is to figure out what the truthmakers are for all those claims that we accept as true. Even if you want to really go basic, what are the fundamental or most basic truthmakers that are needed to make all the other claims true? And then there's hope among some of these folks that we can find what the fundamental truthmakers are for claims, say, about tables and chairs, for example, or about social organizations or gender or whatever.

I think this is, to begin with, a problematic project, because there's always alternative ways to describe what the truthmakers are for any claim we accept as true, even when it looks like it's just describing the world. This is what I call the ontological flexibility of language. Suppose you take a really simple descriptive claim like, "This apple is red." What's the truthmaker for that? Well, you could put it different ways. You could say it's a certain substance, an apple, instantiating a certain property of redness. You could say it's a substance, an apple, that has a certain redness trope.

Some people don't like that way of talking. They'll say, it's the state of affairs of the apple's being red, or even it's the appling redly around here. We can put it all in adverbial terms, but which of these is the real truthmaker? How do we tell? There's just no satisfying answer given. So if you want to appeal to truthmakers to try to figure out the fundamental ontology of the world, what really exists, it looks like there's just no program for figuring out which of many alternatives it is.

But that's not the worst of it. Even you can pull back from that and not use truthmaker theory to try to figure out what the fundamental constituents of reality are that make all our claims true. But rather, you can at least, and a lot more of the truthmaker theorists take this approach, treat it as a constraint. Whatever truths you accept, you've got to be willing to at least say what worldly truthmakers there are for them. If not, you're cheating.

Armstrong said this in response to Ryle's work on philosophy of mind and said, look, if you tell me that there's some truths about dispositions, say the disposition of the glass to break, I want to know, Armstrong said, what it is in the world that makes these true, and if not, you're just cheating by employing talk of dispositions. But again, I think this is just a mistake. This relies on seeing all discourse in the same way. Now, not as with the Neo-Quineans, as positing things that will be explanatory in our best scientific theories, but as trying to describe features of the world that can make it true. All working on the model of discourse like the dog is under the elm, or the apple is red, or something like this, observational, descriptive discourse.

But you can't just go around assuming that all language works that way and has the function of describing the world. In fact, there's really prominent and interesting philosophical theories in other areas that would deny that. So there are, especially in metaethics, there have been these views that say, look, moral discourse, it's not trying to describe moral properties, it's trying to prescribe, there's this prescriptivist views, how we ought to behave, or it's expressing our attitudes towards different kinds of actions. I'll come back to all this in the lecture on moral discourse.

But there are these prominent and viable alternative philosophical theories that will say some prominent areas of discourse aren't just trying to describe the world at all, and that the demand that we give truthmakers in the world to say what makes them true is just inappropriate, a demand we should just shake our heads at and reject as a demand. So the truthmaker approach to metaphysics, even in its weak version, again assumes a functional monism, slightly different from the other one. Not that all the noun terms of interest serve or should serve as explainers in our best scientific theories, but that all of our indicative statements, declaratives, clauses in English, attempt to describe the world in such a way that it makes sense that we ask what is it that makes them true.

Now, of course, you may have got some concerns, like, if we don't say the world's got to make our claims true, how can we understand truth? How can we keep the idea that some claims just are true and others false, regardless of what we prefer or desire or whatever? I'll come back to that in the lecture on truth.

## Critique of the Grounding Approach

But I think as an approach to metaphysics, the truthmaker approach should not be accepted, certainly as a generalized approach to what we're doing if we take the job of metaphysics to involve understanding all forms of discourse, including moral and modal discourse, truth talk, number talk, et cetera.

Beyond those, an approach to metaphysics that's been really popular in the last 20 years, maybe less, is an approach that sees the job of metaphysics, not as figuring out what there is or as finding truthmakers, but rather as concerned with what gets called grounding questions. This is an approach that was popularized by the work of Jonathan Schaffer, and he said something like this. The question of metaphysics isn't what exists. A lot of those questions are easy to answer, like are there chairs? Yes, obviously. Here's some now. But rather, what grounds what? So what's more fundamental and what does it ground at the less fundamental way?

So this has some appeal, I think, for at least understanding certain kinds of relations. Some of my early work was on works of art, artifacts, works of literature. So you can ask really interesting questions about what grounds a work of literature. Could it exist without the existence of meaningful language, of an author intentionally producing it, of a capable readership, et cetera. You can ask interesting grounding questions also about things like races and genders. Would they exist at all without our kinds of attitudes and norms?

So I don't mean to reject all grounding questions. Some local grounding questions I think are interesting and appropriate. Though I think we do have to ask how can we find out what the true answers are? How do we get a good answer? How do we reconcile these? This comes back to the problem of epistemological mystery that I mentioned before.

I think the way to do this is to go by way of understanding how the concepts work, that the concept of, say, a work of literature is the concept of something that is intentionally created by an author in a certain tradition and so on. In that way, I think we can make the epistemology of these kinds of grounding claims clear. But also, I think we've got to be really careful not to overgeneralize. So you get these really impossible-seeming grounding questions.

Here's a classic one. So you may have heard of the problem of the statue and the lump of clay. In some sense, you might want to say the statue just is the lump of clay. And yet it seems like, as philosophers would say, they have different modal properties. That is to say, you could still have the lump of clay if you squashed it back down, but you wouldn't still have the statue, and it certainly wouldn't be the same statue if you squashed it. So the lump has the property of being capable of surviving being squashed. The statue does not.

Oh, but they have all the same physical properties. So what could possibly ground these modal differences between the statue and the clay? That's the grounding problem. But again, I think there's a problem here in assuming that all our terms, including our modal terms, just work to describe bits of reality. So we want to know what grounds these differences in the modal properties. If we bring into question instead how do modal terms work at all, are they even trying to describe the world? Then the demand for thinking that we should be able to find some worldly features that ground the modal differences between the statue and the clay should go away.

All right, so that's at least several, it's certainly not all of the recent ways of thinking of metaphysics that have been popular since the revival of metaphysics that began in the 1950s. Most of the ones I've just described to you have really been since about the year 2000 they've become popular. The moral of the story that I want to give you so far is this, all of these ways of thinking about the work of metaphysics, again, notice they're all recent, they all rely on what I've called the metaphysical malady, and that is this, thinking of metaphysics as addressing all topics of discourse, addressing questions not just about physical objects, but also about possibility, about morality, about properties, about numbers, about freedom, about time, about minds, et cetera.

## The Metaphysical Malady Summarized

Totally general, while at the same time assuming a functional monism, that all these areas of discourse work in the same way, whether it's to posit things to serve in our explanatory theories or to describe features of the world that could make those statements true. So that all we have to do now is just ask, well, what's the nature of modal properties or moral obligations or numbers? And go about doing our metaphysics. I think that's a mistake, and I think we can see it clearly once we recognize the different kinds of functions that these different areas of discourse serve.

Once we accept a functional pluralist view, then we shouldn't demand, we can see why it's a mistake to demand that all of our noun terms of interest in metaphysics ought to refer to things that add explanatory power to our theories, and we should reject them if they don't. We should also reject the idea that discourse is always better to the extent that it tracks the structure of the world, or that we must find some portion of reality to serve as the truth maker for every claim we accept as true, or that it's always appropriate to ask for what's called a metaphysical explanation of what so-called higher-level facts about statues are grounded in, say, physically.

So that's where I think it goes wrong. What can we do instead? Well, the first recommendation is a really simple one. I just want to insist that before you jump into a metaphysical question, asking about the existence or nature of time, possibility, moral obligation, whatever, just pause. You're asking that question using language. Pause and take a step back to ask questions first about how that language works.

## Functional Pluralism and Conceptual Engineering

What functions does it serve for us in human life, in developing our theories, in enabling us to live together, whatever? And how does it get introduced to language? How could it even be learnable at all? And what sorts of rules does it follow? Only then, I think, can we get a clear sense of what metaphysical questions are appropriate and are answerable, and of what demands are appropriate and what are just misguided based on artificially generalizing claims about one area of discourse, say, explanatory scientific theories, to everything whatsoever.

What's the alternative? Well, the alternative that I will be suggesting in these lectures is instead to think of the work we have to do in metaphysics as a kind of conceptual engineering. Well, what's conceptual engineering and how can we do it? And can we do it in a structured, non-arbitrary way? I'll be talking about that in the next two lectures and about how that relieves us of the old problems of these kinds of views of metaphysics that I've been talking about here, while still preserving a lot of the really good work in the history of philosophy, including the history of metaphysics. And then I'll turn from there to talk about how it sheds light on old metaphysical problems about properties, numbers, moral facts, and truth.