My main research interests lie in philosophy of mind and cognitive science. I am particularly interested in the nature of belief, dual-process theories of reasoning, and phenomenal consciousness.

The nature of belief

My early research was on the nature of belief and belief-desire explanation. Building on ideas by Ronald de Sousa, Daniel Dennett, and Jonathan Cohen, I argued that the folk-psychological term ‘belief’ refers to two distinct types of mental state, which have different properties and support different kinds of mental explanation. Building on this claim, I proposed a layered model of the human mind, in which a biologically based ‘basic mind’ supports an actively constructed, conscious ‘supermind’. This work culminated in a monograph, Mind and Supermind (2004), which set out the two-level framework and explored its implications for issues in philosophy of mind. A subtheme of this work was the threat of eliminativism about belief — a threat which, I argued, diminishes once we distinguish different levels of belief. I continue to explore the implications of a two-level conception of belief our understanding of various issues, including the nature of judgement, delusions, implicit bias, and conscious thought.

Dual-process theories

The layered model of mind developed in Mind and Supermind has strong connections with ‘dual-process’ theories in cognitive and social psychology, and I went on to explore these connections. In 2006, I initiated the first-ever international conference dedicated specifically to dual-process theories, which I co-organized with Professor Jonathan Evans of the University of Plymouth. Jonathan and I later co-edited a collection of papers derived from the conference, In Two Minds: Dual Processes and Beyond, which represented the state of the art in the field. The volume also contained a long historical chapter co-authored by Jonathan and myself and my own paper ‘Systems and levels’, which proposed a two-level reinterpretation of dual-process theory. I continue to engage with scientific work in the dual-process tradition and to explore its implications for issues in philosophy.


My other major interest is in the explanation of phenomenal consciousness, where I take a robustly materialist stance. Initially tempted by a realist ‘type-B’ materialism, I attempted to rebut the zombie argument by showing that a parallel conceivablity argument (‘The anti-zombie argument’) can be run for materialism. In later work, however, I rejected phenomenal realism, questioning the coherence of the weak conception of qualia typically employed by materialists and arguing that materialists should be thoroughgoing eliminativists about qualia. Developing this view, I now advocate what I call ‘illusionism’ about consciousness — the view that phenomenality is an introspective illusion. I have defended this view on numerous occasions (including on a 2014 ‘consciousness cruise’ off Greenland), and in 2016 I prepared a target article on the topic for a special issue of Journal of Consciousness Studies, which included responses by supporters and critics of the position. I have also written a textbook on consciousness for an Open University course and am currently working on a new short introduction to the field.

Other interests

I also have research interests in the philosophy of language, philosophical logic, philosophy of action, and epistemology. I have published papers on the semantics of indirect discourse and conversational implicature (with Maria Kasmirli) and have co-edited a volume of research papers in philosophy of action, New Waves in Philosophy of Action.


I am a strong believer in the importance of interdisciplinary collaboration. In my early days at Sheffield, I was closely involved in the work of the Hang Seng Centre for Cognitive Studies and was co-editor of the interdisciplinary web journal Connexions and a weblog on evolutionary topics, Evolving Ideas. At The Open University I was for several years as Director of Mind, Meaning, and Rationality Research Group , and since relocating to Greece I have been affiliated with the University of Crete’s Brain and Mind Program, which acts as focus for a community of researchers in cognitive science and AI. I have also co-edited two interdisciplinary volumes in the ‘Cambridge Handbooks’ series, The Cambridge Handbook of Artificial Intelligence and The Cambridge Handbook of Cognitive Science (with William Ramsey of the University of Nevada).