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I am a Singaporean PhD candidate in Philosophy at UCSD.

My CV can be found here. 


Science is often held as a paradigm of knowledge, and I believe it is a task of philosophy to subject it to the highest scrutiny. In this vein, my primary interests center on the philosophy of science, with particular interests in the history and philosophy of thermodynamics, and philosophy of physics more generally. I am especially interested in how thermodynamic concepts - such as equilibrium, temperature, and entropy - get extended past their original domain of applicability, and whether justifications from the original domain are transferrable to these new domains. I am also interested in the problem of time in quantum gravity, and various proposals for resolving it. Recently, I became interested in studying the justifications behind the use of idealizations in physics, and science more generally.


Right now, I am working with Eddy Keming Chen on two projects on density matrix realism: one related to justifying the Born rule in Everettian quantum mechanics, and another related to an assessment of the 'ontological models' framework and implications for the PBR theorem.


On the side, I dabble in formal epistemology, data ethics, and the philosophy of logic and mathematics.


I completed my undergraduate studies with double first-class honours in philosophy at Wolfson College, University of Cambridge, where I was trained in most areas of analytic philosophy. I then spent some time at the Munich Center for Mathematical Philosophy before coming to UCSD for my PhD. For what it's worth, my Erdös number is 5.


When I am not doing philosophy, I can be found playing Magic: the Gathering, video games, and board games, or skateboarding.

 

News

 
Image by Mingwei Lim

I will be giving a talk at the California Quantum Interpretation Network's 2022 meeting, on recent work with Eddy Keming Chen, "Branching and the Born Rule for a Mixed-State Everettian Multiverse"

Education

2018 -

PhD Philosophy, 
University of California San Diego

2017 - 2018

MA Logic and Philosophy of Science, 
Munich Center for Mathematical Philosophy
(incomplete, left early for PhD)

2014 - 2017

BA & MA (Cantab) Philosophy,
University of Cambridge

 

Publications

T Falls Apart: On the Status of Classical Temperature in Relativity

(Accepted in Philosophy of Science, winner of the 18th Clifton Prize in Philosophy of Physics)

Taking the formal analogies between black holes and classical thermodynamics seriously seems to first require that classical thermodynamics applies in relativistic regimes. Yet, by scrutinizing how classical temperature is extended into special relativity, I argue that it falls apart. I examine four consilient procedures for establishing the classical temperature: the Carnot process, the thermometer, kinetic theory, and black-body radiation. I show how their relativistic counterparts demonstrate no such consilience in defining relativistic temperature. As such, classical temperature doesn’t appear to survive a relativistic extension. I suggest two interpretations for this situation: eliminativism akin to simultaneity, or pluralism akin to rotation.

Degeneration and Entropy

(2022, in Lakatos’s Undone Work: The Practical Turn and the Division of Philosophy of Mathematics and Philosophy of Science, special issue of Kriterion: Journal of Philosophy, edited by S. Nagler, H. Pilin, and D. Sarikaya.)

Lakatos’s analysis of progress and degeneration in the Methodology of Scientific Research Programmes is well-known. Less known, however, are his thoughts on degeneration in Proofs and Refutations. I propose and motivate two new criteria for degeneration based on the discussion in Proofs and Refutations – superfluity and authoritarianism. I show how these criteria augment the account in Methodology of Scientific Research Programmes, providing a generalized Lakatosian account of progress and degeneration. I then apply this generalized account to a key transition point in the history of entropy – the transition to an information-theoretic interpretation of entropy – by assessing Jaynes’s 1957 paper on information theory and statistical mechanics.

No Time for Time from No-Time

(with Craig Callender, Philosophy of Science 88:5, 2021)

Programs in quantum gravity often claim that time emerges from fundamentally timeless physics. In the semiclassical time program time arises only after approximations are taken. Here we ask what justifies taking these approximations and show that time seems to sneak in when answering this question. This raises the worry that the approach is either unjustified or circular in deriving time from no–time.

Does Von Neumann Entropy Correspond to Thermodynamic Entropy? 
(Philosophy of Science 88:1, 145-168, 2021)

Conventional wisdom holds that the von Neumann entropy corresponds to thermodynamic entropy, but Hemmo and Shenker (2006) have recently argued against this view by attacking von Neumann's (1955) argument. I argue that Hemmo and Shenker's arguments fail due to several misunderstandings: about statistical mechanical and  thermodynamic domains of applicability, about the nature of mixed states, and about the role of approximations in physics. As a result, their arguments fail in all cases: in the single-particle case, the finite-particles case, and the infinite-particles case.

Improving LIME Robustness with Smarter Locality Sampling 
(2020, with Sean Saito, Rocco Hu and Nicholas Capel, AdvML '20: Workshop on Adversarial Learning Methods for Machine Learning and Data Mining, KDD2020, August 24, 2020, San Diego, CA.)

(Video of talk available here.) 

Explainability algorithms such as LIME have enabled machine learning systems to adopt transparency and fairness, which are important qualities in commercial use cases. However, recent work has shown that LIME's naive sampling strategy can be exploited by an adversary to conceal biased, harmful behavior. We propose to make LIME more robust by training a generative adversarial network to sample more realistic synthetic data which the explainer uses to generate explanations. Our experiments demonstrate that our proposed method demonstrates an increase in accuracy across three real-world datasets in detecting biased, adversarial behavior compared to vanilla LIME. This is achieved while maintaining comparable explanation quality, with up to 99.94% in top-1 accuracy in some cases.

An Empirical Route to Logical ‘Conventionalism’
(2017, In: Baltag A., Seligman J., Yamada T. (eds) Logic, Rationality, and Interaction. LORI 2017. Lecture Notes in Computer Science, vol 10455. Springer, Berlin, Heidelberg.)

The laws of classical logic are taken to be logical truths, which in turn are taken to hold objectively. However, we might question our faith in these truths: why are they true? One general approach, proposed by Putnam and more recently Dickson or Maddy, is to adopt empiricism about logic. On this view, logical truths are true because they are true of the world alone – this gives logical truths an air of objectivity. Putnam and Dickson both take logical truths to be true in virtue of the world’s structure, given by our best empirical theory, quantum mechanics. This assumes a determinate logical structure of the world given by quantum mechanics. Here, I argue that this assumption is false, and that the world’s logical structure, and hence the related ‘true’ logic, are underdetermined. This leads to what I call empirical conventionalism.

Is Logic Empirical? Logical 'Conventionalism' from an Empirical Standpoint
(2017, Aporia Vol. XVII, Recipient of the Aporia Essay Prize)

The laws of classical logic are taken to be logical truths, and logical truths are taken to objectively hold. However, we might question our faith in these truths: why are they true? One often avoided approach is logical conventionalism, because it makes the logical truths dependent on somewhat intersubjective linguistic conventions. Another approach, proposed by Putnam (1975) and more recently Dickson (2001) or Maddy (2007), is to adopt empiricism about logic. On this view, logical truths are true because they are true of the world alone – this gives logical truths an air of objectivity unlike logical conventionalism. Putnam and Dickson both take logical truths to be true in virtue of the world’s structure, and the structure of the world is to be understood to be given by our best empirical theory, quantum mechanics. As it turns out, the structure of quantum mechanics apparently makes true the laws of quantum logic, and falsifies (one half of) the distributive law, something which was taken to be a logical truth under classical logic. Empiricists take this to indicate that the distributive law was not a logical truth to begin with. However, this argument assumes that there is a single determinate structure of the world prescribed by quantum mechanics. In this essay, I argue that this assumption is false, and that the structure of the world is underdetermined in quantum mechanics. Likewise, the choice of ‘true’ logic, as given by the world’s structure, is also underdetermined. This leads to what I call empirical conventionalism: the world alone fails to determine our logical truths. We need something broadly intersubjective, and thus less than objective, to fix our choice of logic even under empiricism. An attempt to avoid one form of conventionalism has thus led us back to another.

 

Drafts and Works in Progress

Decoherence, Branching, and the Born Rule for a Mixed-State Everettian Multiverse (joint work with Eddy Keming Chen)

Everettians have tried to justify the Born rule by using self-locating uncertainty (e.g. Sebens and Carroll 2014, Vaidman and McQueen 2018) and decision theory (Deutsch 1999, Wallace 2012). However, they focus exclusively on a pure-state Everettian multiverse, for which the quantum state of the multiverse is represented by a wave-function. Recent works in quantum foundations (e.g. Chen 2018) suggest that it is viable to consider a mixed-state Everettian multiverse, for which the quantum state of the multiverse is represented by a (mixed-state) density matrix. In this work, we work out the conceptual foundations for decoherence in a mixed-state multiverse, and show that the standard justifications of the Born rule in the case of a pure state can be extended to the case of a mixed state. Furthermore, the extended justifications provide a unification of 'classical' and 'quantum' probability in terms of self-location and epistemic uncertainty. The resultant theory is arguably simpler than the pure-state version of Everettian quantum mechanics.

The Time in Thermal Time

Attempts to quantize gravity in the Hamiltonian approach lead to the 'problem of time'; the resultant formalism is often said to be `frozen', non-dynamical, and fundamentally timeless. To resolve this problem, Connes & Rovelli (1994) suggest the adoption of a `thermal time hypothesis': the flow of time emerges thermodynamically from a fundamentally timeless ontology. While statistical states are typically defined to be in equilibrium with respect to some background time,  Connes & Rovelli propose that we instead define time in terms of these statistical states: statistical states define a time according to which they are in equilibrium. To avoid circularity, we better have a good conceptual grasp on notions such as `equilibrium' and `statistical state' which are independent of time. Here, however, I argue that these concepts either implicitly presuppose some notion of time, or cannot be applied justifiably yet to the fundamentally timeless context.

Check, Please: De-idealizing De-idealizations

It is doubtless that scientific inquiry inextricably involves the use of idealizations: for ease of calculation and representation, we assume the absence of friction, the perfect sphericity of cows, or the impeccable rationality of human beings. Idealizations are, strictly speaking, false. Yet they play a crucial role in many of our best sciences in representing all sorts of phenomena, from coffee cups to black holes. Much ink has thus been spilled over how to justify them. A predominant view focuses on justifying these idealizations via de-idealization procedures. A more recent cluster of views, due to Potochnik (2017) and Knuttila & Morgan (2019), pushes back by arguing that these idealizations stand on their own and need no explicit de-idealization, and that de-idealization is too demanding, respectively. I’ll argue that this disagreement hinges on a strong philosopher’s construct of de-idealization, an idea that itself needs to be de-idealized. I explicate two weaker senses in which idealizations can be de-idealized.

Do Black Holes Evaporate?

Since Hawking first predicted that black holes lose mass and `evaporate' via Hawking radiation, the phenomenon has become a linchpin of black hole research. However, I will argue that we lack justification for thinking that black hole evaporation occurs. The derivation of black hole evaporation requires some global notion of energy conservation, which in turn rests on assuming that the spacetime in question has certain idealized properties; the ubiquitous ones are stationarity and asymptotic flatness. By examining these idealizations and how they cannot be appropriately `deidealized' in describing actual physical systems, I argue that we lack justification for concluding that actual black holes evaporate.

 
 

Teaching

The word “epistemology" stems from the Greek words “episteme” and “logos”, translated roughly as “knowledge", and “reason" or “argument", respectively. In short, epistemology is the branch of philosophy which focuses on the study of the various aspects of knowledge, asking questions like “what can we know?", “how do we know?", “what are the conditions for  knowledge?", and “what are we justified in knowing?", among other questions.


In this course, we will focus on the study of scientific knowledge. Interestingly, the word “science" stems from the Latin “scientia", which also translates roughly to “knowledge". After all, a paradigm of contemporary human knowledge is scientific knowledge. We frequently appeal to and rely on scientific knowledge: our GPS works because of general relativity, our semiconductors are designed with quantum-mechanical principles in mind, and we take vaccines because we think the science behind it is trustworthy, etc. But what is scientific knowledge? How do we acquire scientific knowledge? These two questions will be the driving questions of our course for the next five weeks, and I hope you will walk away from this course with at least some tentative answers to these big questions.

Organized Desk