Carnegie Mellon University

Upcoming Workshops


June 25-29, 2018

We are excited to announce that in June 2018, the Department of Philosophy, with support from across the campus, will host the upcoming North American Summer School in Logic, Language and Information. NASSLLI is a biennial event inaugurated in 2001, which brings together faculty and graduate students from around the world, for a week of interdisciplinary courses on cutting edge topics at the intersection of philosophy, linguistics, computer science and cognitive science. The Summer School aims to promote discussion and interaction between students and faculty in these fields. High level introductory courses allow students in one field to find their way into related work in another field, while other courses focus on areas of active research. With its focus on formalization and on cross-disciplinary interactions, NASSLLI is a natural fit for us here at CMU. We are delighted to be hosting. The summer school will take place June 25-29, 2018, with preparatory events June 23-24.

Past Workshops and Conferences

Information, Causal Models and Model Diagnostics

April 14-15, 2018

Co-sponsored by the Info-Metrics Institute and Dietrich College of Humanities & Social Sciences

The fundamental concepts of information theory are being used for modeling and inference of problems across most disciplines, such as biology, ecology, economics, finance, physics, political sciences and statistics (for examples, see Fall 2014 conference celebrating the fifth anniversary of the Info-Metrics Institute).

The objective of spring 2018 workshop is to study the interconnection between information, information processing, modeling (or model misspecification and diagnostics) and causal inference. In particular, it focuses on modeling and causal inference with an information-theoretic perspective.

Background: Generally speaking, causal inference deals with inferring that A causes B by looking at information concerning the occurrences of both, while probabilistic causation constrains causation in terms of probabilities and conditional probabilities given interventions. In this workshop we are interested in both. We are interested in studying the modeling framework - including the necessary observed and unobserved required information - that allows causal inference. In particular we are interested in studying modeling and causality within the info-metrics - the science of modeling, reasoning, and drawing inferences under conditions of noisy and insufficient information - framework. Unlike the more 'traditional' inference, causal analysis goes a step further: its aim is to infer not only beliefs or probabilities under static conditions, but also the dynamics of beliefs under changing conditions, such as the changes induced by treatments or external interventions.

This workshop will (i) provide a forum for the dissemination of new research in this area and will (ii) stimulate discussion among research from different disciplines. The topics of interest include both, the more philosophical and logical concepts of causal inference and modeling, and the more applied theory of inferring causality from the observed information. We welcome all topics within the intersection of info-metrics, modeling and causal inference, but we encourage new studies on information or information-theoretic inference in conjunction with causality, model specification (and misspecification). These topics may include, but are not limited to:

  • Causal Inference and Information
  • Probabilistic Causation and Information
  • Nonmonotonic Reasoning, Default Logic and Information-Theoretic Methods
  • Randomized Experiments and Causal Inference
  • Nonrandomized Experiments and Causal Inference
  • Modeling, Model Misspecification and Information
  • Causal Inference in Network Analysis
  • Causal Inference, Instrumental Variables and Information-Theoretic Methods
  • Granger Causality and Transfer Entropy
  • Counterfactuals, Causality and Policy Analysis in Macroeconomics



Category Theory Octoberfest

October 28-29, 2017

View slides from Dana Scott’s Talk: What is Explicit Mathematics?

The 2017 Category Theory Octoberfest will be held on the weekend of Saturday, October 28 and Sunday, October 29 at Carnegie Mellon University in Pittsburgh. Following the tradition of past Octoberfests, this is intended to be an informal meeting, covering all areas of category theory and its applications.

Talks by PhD students and young researchers are particularly encouraged!

Details and travel information can be found here:


There is no registration fee.  Registration is optional, but participants are requested to contact the organizers in advance, especially if they would like to give a talk.  To register and/or submit a talk, please send email to the organizers with the following information: your name, will you give a talk (yes or no), the title of your talk (if yes).


Steve Awodey
Jonas Frey

Modality and Method Workshop

June 9 and 10, 2017 - Center for Formal Epistemology
Margaret Morrison 103

This workshop showcases cutting-edge applications of modality to an intriguing range of methodological issues, including reference, action, causation, information, and the scientific method. Following the tradition of CFE workshops, it is structured to provide ample time for real interaction with, and between, the speakers.

All are welcome to attend.
For more information please email.

Workshop Speakers:

Alexandru Baltag
Oxford University

Title: Knowing Correlations: how to use questions to answer other questions

Abstract: Informationally, a question can be encoded as a variable, taking various values ("answers") in different possible worlds. If, in accordance to the recent trend towards an interrogative epistemology, "To know is to know the answer to a question" (Schaffer), then we are lead to paraphrasing the Quinean motto: To know is to know the value of a variable. There are two issues with this assertion. First, questions are never investigated in isolation: we answer questions by reducing them to other questions. This means that the proper object of knowledge is uncovering correlations between questions. To know is to know a functional dependence between variables.

Second, when talking about empirical questions/variables, the exact value/answer might not be knowable, and instead only "feasible answers" can be known: this suggests a topology on the space of possible values, in which the open neighborhoods of the actual value represent the feasible answers (knowable approximations of the actual value). A question Q epistemically solves question Q' if every feasible answer to Q' can be known if given some good enough feasible answer to Q. I argue that knowability in such an empirical context amounts to the continuity of the functional correlation. To know is to know a continuous dependence between variables.

I investigate a logic of epistemic dependency, that can express knowledge of functional dependencies between (the values of) variables, as well as dynamic modalities for learning new such dependencies. This dynamic captures the widespread view of knowledge acquisition as a process of learning correlations (with the goal of eventually tracking causal relationships in the actual world).

There are interesting formal connections with Dependence Logic, Inquisitive Logics, van Benthem's Generalized Semantics for first order logic, Kelly's notion of gradual learnability (as well as the usual learning-theoretic notion of identifiability in the limit), and philosophically with Situation Theory and the conception of "information-as-correlation". 

Adam Bjorndahl
Carnegie Mellon University

Title: Logic and Topology for Knowledge, Knowability, and Belief

Abstract: In recent work, Stalnaker (2006) proposes a logical framework in which belief is realized as a weakened form of knowledge. Building on Stalnaker's core insights, and using frameworks developed in (Bjorndahl 2016) and (Baltag et al. 2016), we employ topological tools to refine and, we argue, improve on this analysis. The structure of topological subset spaces allows for a natural distinction between what is known and (roughly speaking) what is knowable; we argue that the foundational axioms of Stalnaker’s system rely intuitively on both of these notions. More precisely, we argue that the plausibility of the principles Stalnaker proposes relating knowledge and belief relies on a subtle equivocation between an "evidence-in-hand" conception of knowledge and a weaker "evidence-out-there" notion of what could come to be known. Our analysis leads to a trimodal logic of knowledge, knowability, and belief interpreted in topological subset spaces in which belief is definable in terms of knowledge and knowability. We provide a sound and complete axiomatization for this logic as well as its uni-modal belief fragment. We also consider weaker logics that preserve suitable translations of Stalnaker's postulates, yet do not allow for any reduction of belief. We propose novel topological semantics for these irreducible notions of belief, generalizing our previous semantics, and provide sound and complete axiomatizations for the corresponding logics.

This is joint work with Aybüke Özgün.

Michael Caie

University of Pittsburgh

Title: Classical Opacity

Abstract: In Frege's well-known example, Hesperus was known by the Greeks to rise in the evening, and Phosphorus was not known by the Greeks to rise in the evening, even though Hesperus is Phosphorus. A predicate F such that for some a and b, a=b, Fa and not Fb is said to be opaque. Opaque predicates appear to threaten the classical logic of identity. The responses to this puzzle in the literature either deny that there are cases of opacity in this sense, or deny that one can use classical quantificational logic when opacity is in play. In this paper we motivate and explore the view that there are cases of opacity and that classical quantificational logic is valid even when quantifying in to opaque contexts. We develop the logic of identity given these assumptions in the setting of higher-order logic. We identify a key choice-point for such views, and then develop alternative theories of identity depending on how one makes this choice. In closing, we discuss arguments for each of the two theories.

Melissa Fusco
Columbia University

Title: Deontic Modality and Classical Logic

Abstract: My favored joint solution to the Puzzle of Free Choice Permission (Kamp 1973) and Ross's Paradox (Ross 1941) involves (i) giving up the duality of natural language deontic modals, and (ii) moving to a two-dimensional propositional logic which has a classical Boolean character only as a special case.  In this talk, I'd like to highlight two features of this radical view: first, the extent to which Boolean disjunction is imperiled by other natural language phenomena not involving disjunction, and second, the strength of the general position that natural language semantics must treat deontic, epistemic, and circumstantial modals alike.

Dmitri Gallow
University of Pittsburgh

Title: Learning and Value Change

Abstract: Accuracy-first accounts of rational learning attempt to vindicate the intuitive idea that, while rationally-formed belief need not be true, it is nevertheless likely to be true. To this end, they attempt to show that the Bayesian’s rational learning norms are a consequence of the rational pursuit of accuracy. Existing accounts fall short of this goal, for they presuppose evidential norms which are not and cannot be vindicated in terms of the single-minded pursuit of accuracy. They additionally fail to vindicate the Bayesian norm of Jeffrey conditionalization; the responses to uncertain evidence which they do vindicate are not epistemically defensible. I propose an alternative account according to which learning rationalizes changes in the way you value accuracy. I show that this account vindicates the Bayesian’s norm of conditionalization in terms of the single-minded pursuit of accuracy, so long as accuracy is rationally valued.

Franz Huber
University of Toronto

Title: The Modality underlying Causality

Abstract: I will discuss the relationship between extended causal models, which represent two modalities (causal counterfactuals and normality), and counterfactual models, which represent one modality (counterfactuals). 

It is shown that, under a certain condition, extended causal models that are acyclic can be embedded into counterfactual models. The relevant condition is reminiscent of Lewis (1979) "system of weights or priorities" that governs the similarity relation of causal counterfactuals. In concluding I will sketch modal idealism, a view according to which the causal relationship is a mind-dependent construct.

Kevin T. Kelly and 

Konstantin Genin
Carnegie Mellon University

Title: What is Statistical Deduction?

Abstract: The philosophy of induction begins by drawing a line between deductive and inductive inference. That distinction is clear when empirical information can be modeled as a non-trivial proposition that restricts the range of theoretical possibilities—inference is deductive when every possibility of error is excluded by the premise. Recently, topological methods have been used with success to characterize the boundary between induction and deduction for propositional information of that kind. The basic idea is that that the possible, propositional information states constitute a topological space in which the deductively verifiable propositions are open sets. Then refutable propositions are closed sets, decidable propositions are closed-open, and more general topological concepts characterize the hypotheses that are decidable, verifiable, or refutable in the limit. A new justification of inductive inference emerges thereby—an inductive method is justified insofar as it achieves the best possible sense of success, given the topological complexity of the inference problem faced. That revealing, topological approach to empirical information does not apply directly to statistical inference, because statistical information typically rules out no theoretical possibilities whatever—the sample might just be very unlucky. For that reason, the received view in the philosophy of science has been that all statistical inference is inductive. However, some statistical inferences are evidently very similar to deductive inferences—e.g., rejecting a sharp null hypothesis or generating a confidence interval—whereas others are more similar to inductive inferences—e.g., accepting a sharp null hypothesis or selecting a statistical model. The basis for the analogy is that statistically deductive inferences are ''nearly deductive’’, in the sense that they are performed with a guaranteed low chance of error. The key to connecting the topological-propositional perspective on information with statistics is, therefore, to identify the unique topology for which the propositions that are verifiable with low chance of error are exactly the open propositions. In this talk, we show how to do just that. The result opens the door to a free flow of logical/topological insights into statistical methodology.

Tamar Lando
Columbia University
Title: Topology and Measure in Logics for Point-Free Space

Workshop on Exploitation and Coercion

Nov 4-5, 2016 - Center for Ethics & Policy

The Center for Ethics & Policy at Carnegie Mellon University invites paper abstracts for an inaugural Workshop on Ethics and Policy to be hosted November 4-5, 2016 at the CMU campus in Pittsburgh, PA. We are pleased to welcome Richard Arneson as our keynote speaker. In celebration of the 20th Anniversary of the publication of Alan Wertheimer's seminal work Exploitation, the theme for our inaugural workshop is "Exploitation and Coercion".

Download CFP

Attitudes and Questions Workshop

June 10 and 11, 2016 - Center for Formal Epistemology

Question embedding in natural language allows a subject to be related to a question by either a (traditionally) propositional attitude like knowledge and forgetting, or an (apparently) inherently question-oriented predicate like asking or wondering. Attitudes held of questions are an important locus of research into the semantics of both interrogative clauses and clause-embedding verbs, closely connected with the notion of the answerhood conditions of a question, and with the operations of composition involved in combining these types of predicates with semantically heterogeneous arguments. The attitudes that relate us to questions are also of considerable epistemic interest, touching on the nature of the knowledge relation and on the way that questions structure our inquiries. This workshop aims to bring together a diverse group of experts on the semantics and epistemic issues raised by these phenomena, to promote exchange of theoretical perspectives and approaches, and to help to move forward current work on questions and attitudes.

Workshop Schedule

Workshop Speakers:

Yimei Xiang

Harvard University

Sensitivity to false answers in indirect questions

Interpretations of indirect questions exhibit sensitivity to false answers (FAs). For instance, for John knows who came being true, John must have no false belief as to who came. This paper focuses on the following two facts, which challenge the current dominant view that FA-sensitivity is derived by exhaustifications (Klinedinst & Rothschild 2011): first, FA-sensitivity is involved in interpreting indirect mention-some questions (e.g., John knows where we can buy an Italian newspaper.) (George 2011, 2013); second, FA-sensitivity is concerned with all types of false answers, not just those that can be complete.

Carlotta Pavese

Duke University

Reducibility, George's challenge, and Intermediate Readings: In search for an Alternative Explanation

In my talk I consider a phenomenon that has been used in arguments against the reducibility of knowledge-wh to knowledge-that (George 2013). I defend a new account of the phenomenon that is compatible with reducibility and I argue that it is explanatorily more satisfying than alternative reducibility-unfriendly analyses.

Danny Fox

Massachusetts Institute of Technology

Mention Some, Reconstruction, and Free Choice

The goal of this talk is to present an account of the distribution of “mention some” readings of questions (MS) and to discuss some of the challenges that this account faces. The account will be based on the observation that MS arises only when an existential quantifier intervenes between a wh-phrase and its trace (c.f. George 2011). This observation will be used to argue that reconstruction is necessary for MS and that the notion of exhaustification that reveals itself in the presence of existential quantifiers (resulting in, so called, Free Choice effects) is a crucial component, as well.

Alexandre Cremers

École Normale Supérieure,
Laboratoire de Sciences Cognitives et Psycholinguistique (LSCP)

Plurality effects and exhaustive readings of embedded questions

Questions share many properties with plural nouns. Most famously, Berman (1991) showed that embedded questions can be modified by adverbs of quantity such as 'mostly' or 'in part' (quantificational variability effect). They also give rise to cumulative readings (Lahiri, 2002), and homogeneity effects (observed but not implemented). It has also been shown recently that questions embedded under verbs like 'know' are ambiguous between different exhaustive readings (weak, strong, intermediate). This ambiguity is usually seen as an orthogonal issue, and most recent literature on the various levels of exhaustivity completely ignores plurality effects. I will show how an updated version of Lahiri's (2002) proposal can be combined with ideas from Klinedinst & Rothschild (2011) to yield a theory of strong and intermediate readings on par with recent theories of plurality effects of definite plurals (e.g., homogeneity, cumulative readings) and at the same time compatible with recent experimental results.

Benjamin Spector

Institut Jean Nicod & Ecole Normale Supérieure

Predicting the presuppositions triggered by responsive predicates

Most responsive predicates (predicates which can take both a declarative and an interrogative as an argument, e.g. 'know') are presupposition triggers when they embed declaratives (e.g, x knows that p presupposes p). This raises the question how the presuppositions triggered by responsive verbs when they take a declarative complement are inherited when such verbs take an interrogative complement (assuming that the interrogative-taking use is derived from the declarative-taking use). In Spector & Egré (2015), we made a proposal which seems empirically quite well motivated, but which is stipulative, in that it is not derived from an independently motivated theory of presupposition projection. In this talk, I will show, focusing mostly on polar questions, that it is at the very least very hard to come up with a theory which satisfies simultaneously the two following desiderata:
a) providing a general and uniform semantics for embedded questions under responsive predicates in which the meaning of P+interrogative is deducible from that of P+declarative.
b) deriving the presuppositions of the 'P+interrogative' construction on the basis of current explanatory approaches to presupposition projection.
I will discuss the implications of this observation for theories of embedded questions.

Konstantin Genin

Carnegie Mellon University

Simplicity and Scientific Questions


Ockham’s razor instructs the scientist to favor the simplest theory compatible with current information. There is a broad consensus that simplicity is a principal consideration guiding inductive inference in science. But that familiar observation raises several subtle questions. When is one theory simpler than another? And why should one prefer simpler theories if there is no guarantee that simpler theories are — in some objective sense — more likely to be true? We present a model of empirical inquiry in which simplicity relates answers to an empirical question, and is grounded in the underlying information topology, the topological space generated by the set of possible information states inquiry might encounter. We show that preferring simple theories is a necessary condition for optimally direct convergence to the truth, where directness consists in avoiding unnecessary cycles of opinion on the way to the truth. Our approach relates to linguistics in two ways. First, it illustrates how questions under discussion can shape simplicity and, hence, the course of theoretical science. Second, it explains how, and in what sense, empirical simplicity can serve as a theoretical guide in empirical linguistics.

B. R. George

Carnegie Mellon University

The False Belief Effect for know wh and its Conceptual Neighbors

Spector (2005, 2006) and George (2011, 2013) suggest that the truth know wh ascriptions may depend on which false beliefs the subject of know holds, independent of their propositional knowledge. In this talk, I try to introduce the problem, and to provide a (mostly informal) overview of its apparent connections with exhaustification, presupposition, and the semantics of question-embedding predicates other than know. I try to identify some relevant issues and perspectives, and to highlight a few potential challenges and promising generalizations.

Jonathan Phillips

Harvard University

"Differentiating Contents" CFE/Linguistics Workshop

Saturday, December 5, 2015 - Carnegie Mellon, Baker Hall, Dean’s Conference Room, 154R

A variety of phenomena have motivated researchers to distinguish between different types of linguistic content. One classical distinction is that made by Austin (1962) and Searle (1969) between the propositional content of utterances and their speech act force. Another classical distinction is that between assertoric and presupposed content (Frege 1893, Strawson 1950, Stalnaker 1974, inter alia). In recent years, a new distinction between at-issue and not at-issue content (Potts 2005, Simons et al. 2010) has been introduced, to some extent offered as a replacement for the asserted/presupposed distinction. One empirical domain where the at-issue/not at-issue distinction has been utilized by some researchers is in the study of evidentials, a category of linguistic forms which provide information about the speaker’s evidential relation to the (remaining) content of her utterance.

This one day workshop will bring together researchers with intersecting work on the nature of these distinctions, on the empirical evidence for them, and on how to model them.

Workshop Schedule

Fifteenth conference on Theoretical Aspects of Rationality and Knowledge (TARK 2015)
Co-sponsored by the Center for Formal Epistemology

June 4-6, 2015 - Carnegie Mellon

Pitt/CMU Graduate Student Conference

March 20-21, 2015 - Carnegie Mellon
Locations: Mellon Institute, Room 348 (March 20) and Margaret Morrison, Room A14 (March 21)

Workshop on Simplicity and Causal Discovery
Co-sponsored by the Center for Formal Epistemology

June 6-8, 2014 - Carnegie Mellon

Modal Logic Workshop: Consistency and Structure
Co-sponsored by the Center for Formal Epistemology

Saturday, April 12, 2014 - Carnegie Mellon

Trimester: Semantics of Proofs and Certified Mathematics Trimester at the Institut Henri Poincare

April 7 - July 11, 2014 - Paris, France

Workshop: Philosophy of Physics

September 7, 2013
With Hans Halvorson (Princeton University) and James Weatherall (UC Irvine)

Conference: Type Theory, Homotopy Theory, and Univalent Foundations

September 23-27, 2013 - Barcelona, Spain

Workshop: Case Studies of Causal Discovery with Model Search

October 25-27, 2013 - Carnegie Mellon