Anna Mahtani

Department of Philosophy, Logic and Scientific Method
London School of Economics and Political Science
Houghton Street, London, WC2A 2AE



I'm an Associate Professor at the London School of Economics and Political Science. I work on the philosophy of language, along with decision theory, formal epistemology and welfare economics, and the relationship between these areas.

3rd-Person Bio / CV / ”Meet the Faculty” Video

Anna Mahtani is an Associate Professor in the Department of Philosophy, Logic and Scientific Method at the London School of Economics and Political Science.

She completed her PhD on the Epistemic Theory of Vagueness at the University of Sheffield in 2005. She then took up a British Academy Postdoc at the University of Oxford, before moving to the LSE in 2013. In 2014 she won a Philip Leverhulme Prize.

She has published on a wide range of topics, including vagueness, imaginative resistance, deference principles, imprecise probabilism, arguments for probabilism and the ex ante pareto principle. She is currently writing a book called The Objects of Credence.


Forthcoming. 'Awareness Growth and Dispositional Attitudes', Synthese  (Special Edition) — Decision-Making and Hypothetical Reasoning: Themes in the Philosophy of Richard Bradley.

Forthcoming. 'Dutch book and Accuracy Theorems', Proceedings of the Aristotelian Society .


Dutch book and accuracy arguments are used to justify certain rationality constraints on credence functions. Underlying these dutch book and accuracy arguments are associated theorems, and I show that the interpretation of these theorems can vary along a range of dimensions. Given that the theorems can be interpreted in a variety of different ways, what is the status of the associated arguments? I consider three possibilities: we could aggregate the results of the differently interpreted theorems in some way and motivate rationality constraints based on this aggregation; we could be permissive and accept the conclusions of the dutch book and accuracy arguments under all interpretations of the associated theorems; or we could select one uniquely correct interpretation of the dutch book/accuracy theorem and use that to justify certain rationality constraints. I show that each possibility faces problems, and conclude that dutch book and accuracy theorems cannot be used to justify any principle of rationality.

Forthcoming. 'Frege's Puzzle and the Ex Ante Pareto Principle', Philosophical Studies.


The ex ante Pareto principle has an intuitive pull, and it has been a principle of central importance since Harsanyi’s defence of utilitarianism (to be found in e.g. (Harsanyi 1977)). The principle has been used to criticize and refine a range of positions in welfare economics, including egalitarianism and prioritarianism. But this principle faces a serious problem. I have argued elsewhere (XXX) that the concept of ex ante Pareto superiority is not well defined, because its application in a choice situation concerning a fixed population can depend on how the members of that population are designated. I show in this paper that in almost all cases of policy choice, there will be numerous sets of rival designators for the same fixed population.

I explore two ways that we might complete the definition of ex ante Pareto superiority. I call these the ‘supervaluationist’ reading and the ‘subvaluationist’ reading. I reject the subvaluationist reading as uncharitable, and argue that the supervaluationist reading is the most promising interpretation of the ex ante Pareto principle. I end by exploring some of the implications of this principle for prioritarianism and egalitarianism.

2020. The Dispositional Account of Credence. Philosophical Studies 177 (3):727-745.


In this paper I offer an alternative—the ‘dispositional account’—to the standard account of imprecise probabilism. Whereas for the imprecise probabilist an agent’s credal state is modelled by a set of credence functions, on the dispositional account an agent’s credal state is modelled by a set of sets of credence functions. On the face of it, the dispositional account looks less elegant than the standard account—so why should we be interested? I argue that the dispositional account is actually simpler, because the dispositional choice behaviour that fixes an agent’s credal state is faithfully depicted in the model of that agent’s credal state. I explore some of the implications of the account, including a surprising implication for the debate over dilation.

2019. 'Imprecise Probabilities'. Open Handbook of Formal Epistemology. Pettigrew, R. & Weisberg, J. (eds.) PhilPapers Foundation: 107-130.

2019. Vagueness and Imprecise Credence. Vagueness and Rationality in Language Use and Cognition, Dietz R (ed.). Springer. Switzerland: 7-30.


In this paper I investigate an alternative to imprecise probabilism. Imprecise probabilism is a popular revision of orthodox Bayesianism: while the orthodox Bayesian claims that a rational agent’s belief-state can be represented by a single credence function, the imprecise probabilist claims instead that a rational agent’s belief-state can be represented by a set of such functions. The alternative that I put forward in this paper is to claim that the expression ‘credence’ is vague, and then apply the theory of supervaluationism to sentences containing this expression. This gives us a viable alternative to imprecise probabilism, and I end by comparing the two accounts. I show that supervaluationism has a simpler way of handling sentences relating the belief-states of two different people, or of the same person at two different times; that both accounts may have the resources to develop plausible decision theories; and finally that the supervaluationist can accommodate higher-order vagueness in a way that is not available to the imprecise probabilist.

2019. Basic-Know and Super-Know. Philosophy and Phenomenological Research 98 (2): 375-391.


Sometimes a proposition is 'opaque' to an agent: (s)he doesn't know it, but (s)he does know something about how coming to know it should affect his or her credence function. It is tempting to assume that a rational agent's credence function coheres in a certain way with his or her knowledge of these opaque propositions, and I call this the 'Opaque Proposition Principle'. The principle is compelling but demonstrably false. I explain this incongruity by showing that the principle is ambiguous: the term 'know' as it appears in the principle can be interpreted in two different ways, as either basic-know or super-know. I use this distinction to construct a plausible version of the principle, and then to similarly construct plausible versions of the Reflection Principle and the Sure-Thing Principle.

2018. Imprecise Probabilities and Unstable Betting Behaviour. Noûs 52 (1):69-87.


Many have argued that a rational agent's attitude towards a proposition may be better represented by a probability range than by a single number. I show that in such cases an agent will have unstable betting behaviour, and so will behave in an unpredictable way. I use this point to argue against a range of responses to the ‘two bets’ argument for sharp probabilities.

2018. Vagueness. Routledge Encyclopaedia of Philosophy.

2017. The Ex Ante Pareto Principle. Journal of Philosophy 114 (6): 303-323.


The concept of ‘pareto superiority’ plays a central role in ethics, economics, and law. Pareto superiority is sometimes taken as a relation between outcomes, and sometimes as a relation between actions—even where the outcomes of the actions are uncertain. Whether one action is classed as (ex ante) pareto superior to another depends on the prospects under the actions for each person concerned. I argue that a person’s prospects (in this context) can depend on how that person is designated. Without any constraints on acceptable designators, then, the concept of pareto superiority is ill defined and gives inconsistent results. I consider various ways of completing the definition and draw out some surprising implications.

2017. Deference, Respect and Intensionality. Philosophical Studies 174 (1): 163-183.


This paper is about the standard Reflection Principle (van Fraassen in J Philos 81(5):235–256, 1984) and the Group Reflection Principle (Elga in Nous 41(3):478–502, 2007; Bovens and Rabinowicz in Episteme 8(3):281–300, 2011; Titelbaum in Quitting certainties: a Bayesian framework modeling degrees of belief, OUP, Oxford, 2012; Hedden in Mind 124(494):449–491, 2015). I argue that these principles are incomplete as they stand. The key point is that deference is an intensional relation, and so whether you are rationally required to defer to a person at a time can depend on how that person and that time are designated. In this paper I suggest a way of completing the Reflection Principle and Group Reflection Principle, and I argue that so completed these principles are plausible. In particular, they do not fall foul of the Sleeping Beauty case (Elga in Analysis 60(2):143–147, 2000), the Cable Guy Paradox (Hajek in Analysis 65(286):112–119, 2005), Arntzenius’ prisoner cases (Arntzenius in J Philos, 100(7):356–370, 2003), or the Puzzle of the Hats (Bovens and Rabinowicz in Episteme 8(3):281–300, 2011).

2015. Dutch Books, Coherence, and Logical Consistency’. Noûs 49 (3):522-537.


In this paper I present a new way of understanding Dutch Book Arguments: the idea is that an agent is shown to be incoherent iff he would accept as fair a set of bets that would result in a loss under any interpretation of the claims involved. This draws on a standard definition of logical inconsistency. On this new understanding, the Dutch Book Arguments for the probability axioms go through, but the Dutch Book Argument for Reflection fails. The question of whether we have a Dutch Book Argument for Conditionalization is left open.

2013. with Terry Horgan, Generalized Conditionalization and the Sleeping Beauty Problem. Erkenntnis 78(2): 333-351.


We present a new argument for the claim that in the Sleeping Beauty problem, the probability that the coin comes up heads is 1/3. Our argument depends on a principle for the updating of probabilities that we call ‘generalized conditionalization’, and on a species of generalized conditionalization we call ‘synchronic conditionalization on old information’. We set forth a rationale for the legitimacy of generalized conditionalization, and we explain why our new argument for thirdism is immune to two attacks that Pust (Synthese 160:97–101, 2008) has leveled at other arguments for thirdism.

2012. Diachronic Dutch Book Arguments. Philosophical Review 121 (3): 443-450.


The Reflection Principle can be defended with a Diachronic Dutch Book Argument (DBA), but it is also defeated by numerous compelling counter-examples. It seems then that Diachronic DBAs can lead us astray. Should we reject them en masse — including Lewis’s Diachronic DBA for Conditionalization? Rachael Briggs’s “suppositional test” is supposed to differentiate between Diachronic DBAs that we can safely ignore (including the DBA for Reflection) and Diachronic DBAs that we should find compelling (including the DBA for Conditionalization). I argue that Brigg’s suppositional test is wrong: it sets the bar for coherence too high and places certain cases of self-doubt on the wrong side of the divide. Given that the suppositional test is unsatisfactory, we are left without any justification for discriminating between Diachronic DBAs and ought to reject them all — including the DBA for Conditionalization.

2012. Imaginative Resistance Without Conflict. Philosophical Studies 158 (3): 415-429.


I examine a range of popular solutions to the puzzle of imaginative resistance. According to each solution in this range, imaginative resistance occurs only when we are asked to imagine something that conflicts with what we believe. I show that imaginative resistance can occur without this sort of conflict, and so that every solution in the range under consideration fails. I end by suggesting a new explanation for imaginative resistance — the Import Solution — which succeeds where the other solutions considered fail.

2008. Can Vagueness Cut Out at Any Order? Australasian Journal of Philosophy 86 (3): 499 – 508.


Could a sentence be, say, 3rd order vague, but 4th order precise? In Williamson 1999 we find an argument that seems to show that this is impossible: every sentence is either 1st order precise, 2nd order precise, or infinitely vague. The argument for this claim is unpersuasive, however, and this paper explains why.

2008. Williamson on Inexact Knowledge. Philosophical Studies 139 (2): 171 - 180.


Timothy Williamson claims that margin for error principles govern all cases of inexact knowledge. I show that this claim is unfounded: there are cases of inexact knowledge where Williamson’s argument for margin for error principles does not go through. The problematic cases are those where the value of the relevant parameter is fixed across close cases. I explore and reject two responses to my objection, before concluding that Williamson’s account of inexact knowledge is not compelling.

2004. The Instability of Vague Terms. Philosophical Quarterly 54 (217): 570–576.


Timothy Williamson's response to the question why we cannot know where the sharp boundaries marked by vague terms lie involves the claim that vague terms are unstable. Several theorists would not accept this claim, and it is tempting to think that this gives them a good objection to Williamson. By clarifying the structure of Williamson's response to the title question, I show that this objection is wrong-headed, and reveal a new line of attack.

Recent professional services

Member of the selection board for conferences run by the British Society for the Philosophy of Science (2017, 2018) and for the Formal Epistemology Workshop (2017, 2020).

Member of the council for the Royal Institute of Philosophy (2017 – present)

Member of the Analysis Trust Committee (2015 – present)

Editor of a section (‘The Reflection Principle’) of the Philpapers website (2015 – present)

Guest editor of The Reasoner (2014)

Conference papers and talks

'Names for Merely Statistical People’, given at Reading University’s departmental seminar (November 2017), under the title ‘The Designators that Matter’ at the workshop on Risk and Aggregation hosted jointly by UCL and LSE (March 2018), at Glasgow’s department seminar (May 2019), at the ANU Thursday Seminar (August 2019), and (in a revised form, as 'The Ex Ante Pareto Principle and Frege's Puzzle') at a workshop on 'Bayesian Epistemology: Perspectives and Challenges' at the MCMP (August 2020).

Accommodating Awareness Growth’, given at a workshop on Severe Uncertainty and Climate Policy in Stockholm (April 2019) and at a conference on 'Accommodating Machine Intelligence' at the ANU (August 2019).

Two-Dimensionalism and the Objects of Credence’, given at the ‘What are Degrees of Belief’ Workshop in Leeds (September 2018).

Vagueness and Imprecise Credence’ given at the 5th LSE Conference on Philosophy of Probability (June 2016), at the ‘Experience and Updating’ workshop in Bochum (July 2016), and at the Visiting Speakers Seminar series at Stirling (October 2017), all under the name ‘Vague Credence’. Given at the Knowledge, Belief and Evidence Conference in Oxford (May 2018).

Betting Scenarios and Dilation’ given at the Formal Epistemology Gathering workshop in Bristol (April 2017), at the Choice Group LSE (June 2017), and then under the title ‘The Unified Account of Credence’ at Oxford’s Jowett Society (November 2017).

'What the Objects of Credence Cannot Be’, at the Philosophy of Language for Decision Theorists Workshop, LSE (May 2017).

'Arguments for Probabilism', given at Bristol's seminar series (February 2016), at the 'Reasons and Mental States in Decision Theory' workshop at LSE (June 2016), at the Colloquium in York (October 2016), at the LEM seminar at the Institute of Philosophy (November 2016) and in a revised form as 'Dutch Book and Accuracy Arguments' at the Aristotelian Society (June 2020).

'Knowledge and the Sure-Thing Principle', given at the 'Puzzles of Knowledge' workshop in Lisbon (November 2015), and then at the BSPS meeting at the LSE (March 2016).

'Unstable Betting Behaviour and Imprecise Probabilities', given at Birmingham's departmental seminar (March 2015), at the Vienna Forum for Analytic Philosophy (May 2015), at the final conference of the Franco-Swedish Program in Economics and Philosophy in Uppsala (June 2015), and then at the Bristol-Groningen Conference in Formal Epistemology (July 2015).

'How should we designate the people we care about?', given at LSE's Cumberland Lodge weekend (November 2014), at Belfast's departmental seminar (December 2014), and at Nottingham's departmental seminar (January 2015). This paper then morphed into 'How (not) to make everyone better off', and was given under that name at the LSE Forum for European Philosophy (November 2015), to the Munich Centre for Mathematical Philosophy (December 2015), and to a conference for sixth-form pupils at James Allen's Girls' School, London (February 2016). Finally under the name 'The Ex Ante Pareto Principle', this paper was the subject of a 'Authors and Papers' Seminar at Oxford (June 2016).

'Dutch Books, Coherence and Logical Consistency', given at the Theoretical Work in Progress group, Oxford, June 2013 and at the 'Money Pumps, Dutch Books and other Picturesque Devices' workshop at the in Collège d'études Mondiales, Paris (May 2014).

'Deference and Designators', given at the Choice Group, LSE (July 2013), and at the Logic and Language Conference, Institute of Philosophy (March 2014).


Thanks to Bryan Roberts, who designed the template for this website. And to Ewan Rodgers who created it.