Petra Kosonen
Postdoctoral Fellow at the Population Wellbeing Initiative,
University of Texas at Austin
Petra Kosonen
Postdoctoral Fellow at the Population Wellbeing Initiative,
University of Texas at Austin
Petra Kosonen
Postdoctoral Fellow at the Population Wellbeing Initiative,
University of Texas at Austin
My research is mostly on ethics and decision theory. I earned a DPhil in Philosophy from Oxford University. The central theme of my thesis was how we should treat tiny probabilities of vast value.
Thesis
Tiny Probabilities of Vast Value
University of Oxford, 2022
The topic of this thesis is how we should treat tiny probabilities of vast value. This thesis consists of six independent papers. Chapter 1 discusses the idea that utilities are bounded. It shows that bounded decision theories prescribe prospects that are better for no one and worse for some if combined with an additive axiology. Chapter 2, in turn, points out that standard axiomatizations of Expected Utility Theory violate dominance in cases that involve possible states of zero probability. Chapters 3-6 discuss the idea that we should ignore tiny probabilities in practical decision-making. Chapter 3 argues that discounting small probabilities solves the ‘Intrapersonal Addition Paradox’ and thus helps avoid the Repugnant Conclusion. Chapter 4 explores what the most plausible version of this view might look like and what problems the different versions have. Chapter 5 focuses on one type of problem, namely, money pumps. The Independence Money Pump, in particular, presents a difficult challenge for those who wish to discount small probabilities. Finally, Chapter 6 discusses the implications of discounting small probabilities for the value of the far future.
Publications
Probability Discounting and Money Pumps
Philosophy and Phenomenological Research 109 (2), pp. 593-611 (2024).
In response to cases that involve very small probabilities of huge payoffs, some argue that we ought to discount very small probabilities down to zero. However, this paper shows that doing so violates Independence and Continuity, and as a result of these violations, those who discount small probabilities can be exploited by money pumps. Various possible ways of avoiding exploitation will be discussed. However, this paper concludes that the money pump for Independence undermines the plausibility of discounting small probabilities.
Discounting Small Probabilities Solves the Intrapersonal Addition Paradox
Ethics 132 (1), pp. 204-217 (2021).
Nebel argues for the Repugnant Conclusion via the “Intrapersonal Repugnant Conclusion,” on which certainty of a mediocre life is better for individuals than a sufficiently small chance of an excellent life. In this article, I deny that acceptance of the Intrapersonal Repugnant Conclusion leads us to the Repugnant Conclusion. I point out that on many views which avoid the Repugnant Conclusion we should discount very small probabilities down to zero. If we do, then Nebel’s crucial premise of Ex Ante Pareto fails, because discounting at the individual level can fail to match up with discounting at the population level.
Prudential Longtermism
Essays on Longtermism, Oxford University Press (forthcoming), with Johan E. Gustafsson.
According to Longtermism, our acts’ expected influence on the expected value of the world is mainly determined by their effects in the far future. There is, given total utilitarianism, a straightforward argument for Longtermism due to the enormous number of people that might exist in the future, but this argument does not work on person-affecting views. In this paper, we will argue that these views might also lead to Longtermism if Prudential Longtermism is true. Prudential Longtermism holds for a person if and only if our acts’ overall influence on that person’s expected well-being is mainly determined by the acts’ effects in the far future. We argue that (due to a small chance of anti-ageing and uploading) there could be an enormous amount of prudential value for some contemporary person in the far future and that value may be so large that it dominates their overall expectation of lifetime well-being.
Do Lefty and Righty Matter More than Lefty Alone?
Erkenntnis 89 (5), pp. 1921-1926 (2024), with Johan E. Gustafsson.
Derek Parfit argues that fission is prudentially better for you than ordinary death. But is having more fission products with good lives prudentially better for you than having just one? In this paper, we argue that it is. We argue that, if your brain is split and the halves are transplanted into two recipients (who both have good lives), then it is prudentially better for you if both transplants succeed than if only one of them does (other things being equal). This upshot rules out, among other things, that the prudential value of standing in the relation that matters in survival to multiple people is equal to their average well-being.
Work in Progress
How to Discount Small Probabilities
Maximizing expected value leads to counterintuitive choices in cases that involve tiny probabilities of huge payoffs. In response to such cases, some have argued that we ought to discount very small probabilities down to zero. In this paper, I discuss how exactly this view can be formulated. I begin by showing that less plausible versions of discounting small probabilities violate dominance. Then, I show that more plausible formulations of this view avoid these dominance violations, but instead, they violate the axiom of Independence. As a result of this violation, those who discount small probabilities can be exploited by a money pump. I conclude that discounting small probabilities faces significant problems that undermine its plausibility as a theory of instrumental rationality.
Overview of Fanaticism (Introduction to My Thesis)
This paper explores different approaches to cases that involve tiny probabilities of huge payoffs. The main approaches discussed are Probability Fanaticism, Boundedness and Probability Discounting. First, the paper discusses two arguments for maximizing expected utility: the long-run argument and representation theorems. Next, it investigates Probability Fanaticism, on which tiny probabilities of huge positive or negative payoffs can have enormous positive or negative expected utility (respectively). Various arguments for and against Probability Fanaticism are discussed. Then, the paper considers Boundedness, namely, the idea that utilities are bounded. Finally, the paper discusses Probability Discounting, on which tiny probabilities should be ignored in practical decision-making. Some other approaches are also discussed briefly. The paper concludes that the paradoxes involving tiny probabilities of vast value show that some intuitively compelling principles of rationality must be given up.
Expected Utility Theory and Possible States of Zero Probability
At least at first glance, Expected Utility Theory tells us to be indifferent between two prospects when they are otherwise the same, except that one gives a better outcome than the other in a possible state of zero probability. But as some have suggested, Expected Utility Theory might be supplemented with dominance to get the verdict that the dominating prospect is better than the dominated one. However, I will show that if Expected Utility Theory is supplemented with dominance in this way, it will violate the Continuity axiom of Expected Utility Theory.
Pascal’s Hell
A dialogue based on Pascal’s Mugging.
Ignore Outlandish Possibilities (with Tomi Francis)
Expected Utility Theory appears to face two problems. The first one is the Problem of Outlandishness: Our decisions could depend almost entirely on what happens if very outlandish things are true. The second problem is that once we consider gambles with infinitely many possible outcomes, Expected Utility Theory either needs to be bounded, or it will be inconsistent with an infinitary generalisation of the Sure Thing Principle leaving it vulnerable to money pumps. But, Bounded Expected Utility Theory is very difficult to believe in the moral case: It is hard to believe that there could ever be a case where it would be better to save some number of lives for sure than it would be to save any number of lives with probability almost one. In order to solve these two problems, we propose that we should conditionalise on the falsity of outlandish propositions before applying Expected Utility Theory. We suggest two accounts of outlandishness, however, both versions suffer from serious objections. The most significant of these is that both seem to leave an agent vulnerable to money pumps.
Bounded Utilities and Ex Ante Pareto
This paper shows that decision theories on which utilities are bounded, such as standard axiomatizations of Expected Utility Theory, violate Ex Ante Pareto if combined with an additive axiology, such as Total Utilitarianism. A series of impossibility theorems point toward Total Utilitarianism as the right account of axiology, while money-pump arguments put Expected Utility Theory in a favorable light. However, it is not clear how these two views can be reconciled. This question is particularly puzzling if utilities are bounded (as standard axiomatizations of Expected Utility Theory imply) because the total quantity of well-being might be infinite or arbitrarily large. Thus, there must be a non-linear transformation from the total quantity of well-being into utilities used in decision-making. However, such a transformation leads to violations of Ex Ante Pareto. So, the reconciliation of Expected Utility Theory and Total Utilitarianism prescribes prospects that are better for none and worse for some.
Tiny Probabilities and the Value of the Far Future
Morally speaking, what matters the most is the far future—at least according to Longtermism. The reason why the far future is of utmost importance is that our acts’ expected influence on the value of the world is mainly determined by their consequences in the far future. The case for Longtermism is straightforward: Given the enormous number of people who might exist in the far future, even a tiny probability of affecting how the far future goes outweighs the importance of our acts’ consequences in the near term. However, it seems that there is something wrong with a theory that lets very small probabilities of huge payoffs dictate one’s course of action. If instead, we discount very small probabilities down to zero, we may have a response to Longtermism provided that its truth depends on tiny probabilities of vast value. Contrary to this, I will argue that discounting small probabilities does not undermine Longtermism.
The Optimistic Meta-Induction
The justification for existential risk mitigation need not rely on a high subjective credence in these risks. However, many do, in fact, give relatively high probabilities for these risks materializing in the near future. In this paper, I argue that our estimates for the probabilities of existential risks might be undermined by the Optimistic Meta-Induction: The history of humanity is full of doomsday predictions that turned out to be wrong, so we have no reason to believe our current doomsday predictions are approximately right. I explore whether we should lower our subjective credences in near-term existential risks in light of the historical track record of failed predictions. Should we turn back the Doomsday Clock? I discuss various objections to the Optimistic Meta-Induction, such as observation selection effects explaining the continued existence of humanity and past doomsday predictions being the wrong reference class to reason about current doomsday predictions.
A Money Pump Against Knowledge-Based Decision Theories
Some argue that knowledge plays a crucial role in instrumental rationality. The idea is that agents should take into account their knowledge when deliberating what they rationally ought to do. In this paper, I will show that these views are vulnerable to a money pump: Agents who conditionalize on what they know before maximizing expected utility would in some circumstances pay for something they could keep for free. This undermines the plausibility of conditionalizing on knowledge before maximizing expected utility.
Tutoring
ETHICS
St. Catherine’s College, University of Oxford, 2021
I taught one-on-three tutorials on ethics.
PRACTICAL ETHICS
St. Catherine’s College, University of Oxford, 2021
I taught tutorials on practical ethics for one student.
THEORY OF POLITICS
University College, University of Oxford, 2021
I taught one-on-one and one-on-two tutorials on political philosophy for three students.
PHILOSOPHY OF SCIENCE
University of Oxford, 2021
I taught one-on-three tutorials on philosophy of science.
INTRODUCTION TO PHILOSOPHY
Sarah Lawrence Programme, University of Oxford, 2020
I taught philosophy tutorials for one student.