Mark Jago
Lecturer, Faculty of Arts
Contact
Biography
I began doing research in a computer science department, working on logics in AI for reasoning about knowledge and belief. But I felt the draw of bigger questions, and I've ended up working in a philosophy department, writing about truth, knowledge and paradox. For me, the big questions are about how the world ultimately is, and how we can think and know about it. But when this all gets a little too deep, I still dabble in the formal stuff, particularly modal and relevance logics.
Expertise Summary
I've published and given research talks in the following areas:
- Metaphysics: Truth and truthmaking, constitution, facts/states of affairs, modality and counterpart theory, existence and absence
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Epistemology: Knowability, epistemic logic, belief revision
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Formal and philosophical logic: Modal logic, relevant logic, Fitch's paradox
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Philosophy of Language: Propositions, vagueness, content, what is said, indexicals, semantic paradoxes
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Philosophy of Mind: Mental causation, mental content
Research Summary
My current research centers around three themes:
1. Thinking about the impossible
(a) An account of propositions as sets of possible and (non-trivial) impossible worlds. This allows an account of same-saying. It also explains how logically equivalent propositions can be distinct and hence how they can be made true by distinct entities.
(b) An account of epistemic possibility, which is non-trivial in the sense that not every set of sentences represents some epistemic/doxastic possibility, and non-ideal in the sense that some epistemic possibilities are logically impossible. The account can be used to give a semantics for 'knows' and 'believes' (and possibly other psychological attitudes).
2. The Nature of Truth
This project has three components, giving an account of (a) the truthmakers, (b) the truthbearers and (c) the relationship between them. As part of this research, I'm developing an account of (non-linguistic) facts, including negative, conjunctive and existential facts. This is based partially on David Armstrong's account of states of affairs. Formal features are taken from the typed lambda-calculus. Finally, I'm investigating a logic of 'truthmaking entailment', the relation which holds between propositions p and q when all of p's truthmakers also make q true.
3. Making up the world
Selected Publications
MARK JAGO, 2012. The Truthmaker Non-Maximalist's Dilemma Mind.
MARK JAGO, 2012. The Content of Deduction Journal of Philosophical Logic.
JAGO, MARK and BARKER, STEPHEN, 2011. Being Positive About Negative Facts Philosophy & Phenomenological Research.
JAGO, M., 2010. Closure on knowability ANALYSIS -OXFORD-. VOL 70(NUMBER 4), 648-659
Past Research
In my PhD thesis (2006), I developed a logic and modal semantics for modelling rule-based agents (of the type that are being developed in AI for commercial applications) with limited cognitive resources (memory & time in which to reason). I axiomatized the logic and gave a number of proofs: soundness & completeness and a complexity analysis (one problem is in NP, another in PSPACE). For the modal semantics, two particular results are of interest:
- Bisimulation in these models is identical to modal equivalence between states.
- Models have the congruence (Church-Rosser) property.
Future Research
Over the next few years, I'll be working on the following themes:
Metaphysics: Truth and truthmaking, constitution, facts/states of affairs, modality and counterpart theory, existence and absence
Epistemology: Knowability, epistemic logic, belief revision
Formal and philosophical logic: Modal logic, relevant logic, Fitch's paradox
Philosophy of Language: Propositions, vagueness, content, what is said, indexicals, semantic paradoxes
Philosophy of Mind: Mental causation, mental content