Addis specialises in the philosophy of Wittgenstein and related areas as well as having research interests in the philosophies of language, mind, and religion. His book Wittgenstein: Making Sense of Other Minds (1999) was described by Rom Harre as "a careful and subtle study" whose "scholarly merits are great".[2]Wittgenstein and Philosophy of Religion (2001, co-edited with Robert Arrington) is "an interesting and valuable collection of essays",[3] while Wittgenstein: A Guide for the Perplexed (2006) is "a clear, balanced and very recommendable book which gives a good idea of the complexity of Wittgenstein's philosophy".[4]
Wittgenstein : Making Sense of Other Minds (Aldershot: Ashgate, 1999). ISBN0754610438
Wittgenstein: A Guide for the Perplexed (London: Continuum, 2006). ISBN0-8264-8495-6 (hbk), 0-8264-8496-4 (pbk)
Wittgenstein and Philosophy of Religion (co-edited with Robert Arrington, London: Routledge, 2001). ISBN0-415-21780-6 (hbk), 0-415-33555-8 (pbk)
Essays and chapters
'D. Z. Phillips' Fideism in Wittgenstein's Mirror', in Wittgenstein and Philosophy of Religion pp. 85–100
'Wittgenstein and the Transfinite in Set Theory', in Klaus Puhl, ed., Wittgenstein's Philosophy of Mathematics (Vienna: Holder-Pichler-Tempsky, 1993), pp. 87–92. ISBN3-209-01592-9
Entries on Reuben Louis Goodstein pp. 336–7, Margeret Macdonald pp. 601–5, Margeret Masterman pp. 664–5, and David Pears pp. 756–60 in Stuart Brown, ed., Dictionary of Twentieth-Century British Philosophers (Bristol: Thoemmes Press, 2005). ISBN1-84371-096-X (Reprinted in A.C. Grayling, Andrew Pyle, Naomi Goulder eds., Continuum Encyclopedia of British Philosophy (Thoemmes Continuum, London 2006), as Goodstein pp. 1256–7, MacDonald pp. 1997–8, Masterman p. 2104, and Pears pp. 2454–7. ISBN1-84371-141-9)
'Intellectual Property and the Public Interest', in The International Journal of the Book 6:1 (2009), pp. 121–124. ISSN1447-9516
'Wittgenstein's Private Language Argument and Self Consciousness', in Sats-Nordic Journal of Philosophy 8:2 (2007), pp. 89–103. ISSN1600-1974 (Reprinted in Analysis and Metaphysics 6 (Dec. 2007),pp. 288–302. ISSN1584-0778)
'Criteria: the State of the Debate', in Journal of Philosophical Research XX (1995), pp. 139–174. ISSN1053-8364
'Surveyability and the Sorites Paradox', in Philosophia Mathematica 3:2 (1995), pp. 157–165. ISSN0031-8019
'Philosophy in the Workplace', in Philosophy Now 95 (2013)