Faces | Johanna Thoma: The main point of philosophy is to get people to think better – In Conversation

Johanna Thoma is an assistant professor at the Department of Philosophy, Logic and Scientific Method at the London School of Economics.

Her main research is in practical rationality and decision theory and she is particularly interested in questions of rationality over time, and in the context of uncertainty. She also works on ethics and the philosophy of science, in particular the philosophy of social science and economics. This interview was conducted by Catharsis’ editor, Divanshu Sethi.

What got you interested in the field of Philosophy and Economics? What is the relationship between the two?

I studied PPE (Philosophy, Politics and Economics) as an undergraduate, primarily because I was interested in politics, and thought there would be some benefit to an interdisciplinary approach. I didn’t have much prior experience of either economics or philosophy. I got drawn into both fields quite quickly, and for similar reasons: I loved the analytical rigour. And I also started to see connections early on. Most importantly, my economics teachers were talking about rationality and welfare, and were making all sorts of other normative claims – ones that in my philosophy classes, I was learning to question. Thinking back, I think one thing that drew me in at the time is the fact that economists sometimes make these seemingly outrageous claims, offering simple explanations of complex problems, that have a whiff of moral repugnance. I ended up writing my undergraduate dissertation on the question of whether children could be considered to be public goods.

Of course, now I know much more about the connections between the two fields. At the heart of orthodox economics we indeed find a theory of rationality that is philosophically contested. Similarly, welfare economics engages in moral theorizing. Somewhat less obviously, fundamental debates about the nature of causality take place within econometrics. So part of what economists do actually is philosophy. And conversely, philosophers sometimes find themselves doing economics, that is, applying models and methods from economics to philosophical questions. Game theoretic modelling, in particular, has been very popular. I have, for instance, worked on applying economic bargaining theory to moral theories that claim that moral rules are determined by a hypothetical social contract. Next to economists doing philosophy and philosophers doing economics, we also find philosophers of economics who work on the more traditional questions of philosophy of science: How do the methods of economics enable us to learn about the economic world? And what is the ontological status of the theoretical entities economists talk about?

Can you tell us about your interest in decision theory and the significance of it in our daily lives?

At the moment, I am primarily interested in what instrumental rationality – the kind of rationality involved in taking the best means to our ends – requires of us under conditions of risk and uncertainty, on the one hand, and when we make decisions over time, on the other. One interesting question about rationality under risk is the question of whether we can only be risk averse when we value a good less the more we already have of it. This is implied by some popular interpretations of the standard economic theory of rationality. But intuitively, this doesn’t seem to be obvious. Imagine two children, Johanna and Erik, interested in eating only candy. Each prefers a sure 4 pieces to a 50/50 gamble of getting either nothing or 10 pieces of candy. So each of them is risk averse. Johanna chooses in this way because she gets easily satiated: The 7th, 8th, 9th or 10th piece of candy don’t add that much to her wellbeing anymore, and so their prospect doesn’t do much to weigh up the chance of ending up with nothing. But Erik doesn’t get satiated. Each piece of candy is just as good as the last to him. He just opts for the 4 pieces for sure because he is risk averse. Whether and how we can rationally allow for such “pure” risk aversion is a matter of much debate right now. Obviously, this has practical relevance for most of the decisions we make, since most of our decisions involve an element of uncertainty.

The orthodox normative decision theory which is expected utility theory(EU) says that in a state of uncertainty, one should prefer the option with greatest expected desirability or value. What happens when two options are incomparable due to its incommensurable quantities? What kind of impact it has on the theory?

I actually don’t think that EUT is best interpreted as saying that we should pick the action with greatest expected desirability or value. I think the better interpretation is that EUT requires us to have preferences over uncertain prospects that abide by various conditions, such as Savage’s Sure-Thing Principle. If they do, agents can be represented as maximizing the expectation of some utility function. But I think it is a mistake to think that the utility function is a cardinal measure of value or desirability. If that sounds technical, the important point is that I think that the kinds of values that could be incommensurable only feature indirectly in decision theory. Decision theory is about preferences, and imposes consistency conditions on them. Values come in only indirectly, in that, to be instrumentally rational, our preferences should reflect our values.

The case of incommensurable values is one where this difference matters. As I said, if we want to be instrumentally rational, our preferences should reflect our values. Suppose we hold incommensurable values, and they pull in opposite directions in a choice we are facing. As in Sartre’s famous example, suppose you have to choose between joining the Resistance and caring for your elderly mother. I think in those kinds of cases, rationality is permissive about what preferences you can have. You can prefer joining the Resistance, or caring for your mother, or you can be indifferent. One caveat here is that I think there can also be diachronic constraints on you frequently changing your mind on the question. If you eventually become impoverished from buying a train ticket every other day to go back and forth between your mother or the Resistance, something has gone wrong. But as long as you don’t incur such costs, you are free to prefer either. Importantly, then, the incommensurable values do not translate directly into an indeterminate utility function. If you consistently prefer one option over the other despite the incommensurable values involved, you can be represented with a precise utility function.

Many recent studies have highlighted the underrepresentation of women in the fields of Philosophy and Economics. How does it affect the progression of the two fields? What kind of experience has been it for you?

The underrepresentation is noticeable, frustrating, but at the same time doesn’t seem to have an easy explanation. It’s certainly a sad state of affairs for both fields. If nothing else, quality suffers, because both fields are missing out on women who would have been great philosophers and economists, instead recruiting mostly from the pool of men. But I think it also means both fields are missing out on the distinct and valuable points of view women might contribute, given the different life experiences they make in our unequal societies. Similar considerations apply, of course, to many other groups currently underrepresented in both fields.

What do you think is the relevance of philosophy? And for our readers, could you recommend some papers or books to better understand the nature of your philosophical work?

First and foremost, I think philosophy is worthwhile because there is value in contemplation, even if it raises more questions than it answers. And interpersonally, there is value in understanding one another’s arguments, and offering the best versions of our own – even if it doesn’t lead to us converging in our views. Of course, philosophy can also be more directly socially relevant, by informing policy-making, or the way in which economics is conducted. But I think that is secondary. The main point of philosophy is to get people to think, and ideally think better.

For good introductions to the philosophy of economics, I would recommend Hausman, McPherson and Satz’s Economic Analysis, Moral Philosophy, and Public Policy (3rd edition, 2016), and Julian Reiss’ Philosophy of Economics (2013). I wrote up an introduction to decision theory myself for an online handbook, which you can find here.

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