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Dublin Postgraduate Philosophy Conference 2014
'Duality and Opposition'

posterTrinity Long Room Hub Arts and Humanities Research Institute
29th and 30th of March

The philosophy departments of Trinity College Dublin and University College Dublin will host the annual Dublin Graduate Philosophy Conference. The keynote speakers will be Dr. Fabien Schang from Moscow State University and Professor Vasilis Politis from Trinity College Dublin.

The theme of this conference will be 'Duality and Opposition', this has been a perennial topic of study since the earliest philosophies, and also continues to be discussed in a number of other disciplines in the present day. The philosophy of duality and opposition has become a broad and interdisciplinary field. However, we intend this conference to focus on duality and opposition as such, and to address these phenomena themselves, not merely examinations of particular dualities or oppositions. Through this focus we wish to facilitate broad participation in discussion about this most interesting topic.

Some examples of other key terms that are sometimes used to describe the same or related topics are: Antonymy, Polarity, Complementarity, Contradiction, Contrariety, Chirality, Dyadic, Binary, Difference, Enantia, Enantiomorphic, etc.

Please register by email to

Please indicate if you wish to avail of the catered sandwich lunch and refreshments at the conference; a nominal charge will apply (€10 for Saturday, and €8 for Sunday), please indicate if you require a vegetarian option. The deadline for booking catering is 11am on Friday 28 March. There will be a conference dinner on Saturday at around 7.30pm, if you would like to join us, it will be a set menu for €30 per head. Please notify us accordingly.

Provisional Programme:

Saturday 29th March:

9.30am: Arrival and Registration

9.45am: Introduction and Announcements.

Keynote Speaker:
10-11.30am: Fabien Schang (Moscow State University)
Title: 'OF Logic'


12-1.30pm: Keith Begley (Trinity College Dublin)
Title: 'What is this thing called Duality?'


2.30-4pm: Hannah Haejin Kim (Oriel College, University of Oxford)
Title: 'Reality as the Coincidence of Opposites: Alfred North Whitehead on Time and Eternity'


4.30-6pm: Christopher Buckels (Trinity College Dublin)
Title: 'Predicating Opposites in Plato's Sophist'

Sunday 30th March:

9.45am: Arrival

Keynote Speaker:
10-11.30am: Vasilis Politis (Trinity College Dublin)
Title: TBA


12-1.30pm: Flavio Zelazek (Sapienza - Università di Roma)
Title: 'The Tao of Logic'


2.30-4pm: Dónall McGinley (Trinity College Dublin)
Title: 'John Duns Scotus on the Reality of Opposition'


'OF Logic'
Fabien Schang (Moscow State University)

Starting from an intersubjective view of truth as a social construction resulting in a normative agreement, a general theory of meaning is suggested in the form of an interrogative inquiry, namely: a Question-Answer Semantics (thereafter: QAS), according to which the meaning of any object (i.e. whatever meaningful) is given by an ordered set of questions and corresponding answers. While borrowing from Frege's theory of sense and reference, our non-Fregean semantics differs from it by altering the definition of sense and reference at once: the former corresponds to a set of questions characterizing the object at hand, while the latter is the corresponding set of answers. We will restrict to a binary pair of yes-no answers for the present talk, admitting the possibility of indeterminate ontologies with further, non-categorical answers.

The upshot of such a Boolean game stands in-between formal ontology and formal logic. First of all, any given ontology amounts to a given set of objects without preexisting hierarchy (individuals, concepts, sentences, and so on) and defined by questions and answers. Then the relations between any such objects are determined within a formal logic whose model is a Boolean algebra. Above all, this logic is not a standard (Tarskian) one in that the fundamental relation at hand is not consequence but opposition. By this way, the Aristotelian corpus is revisited and leads to an abstract Opposition-Friendly Logic (or 'OF Logic') that echoes with Hintikka and Sandu's Independence-Friendly Logic (or 'IF Logic') in several respects. It is more expressive than the standard truth-functional logic, on the one hand, by introducing a set of opposite-forming operators like e.g. contrariety or subcontrariety. It wants to display a more fine-grained explanation of the diachronic aspect of meaning in natural languages, on the other hand, by means of a general theory of negation that proceeds as a difference-forming operator and largely applies beyond the sole category of sentences. It questions some mainstream assumptions of logic, finally, including the theory of meaning as truth-condition or the view that only sentences can have a logical value.

This logical machinery will be tested in its philosophical motivations and technical results, thereby leading from a holistic view of meaning to a calculus of oppositions through some reflections on the philosophical import of logic as a theory of opposition (rather than consequence). Language game theory and lexical semantics will be emphasized for this purpose.

Blanché, Robert. Structures Intellectuelles (essai sur l'orginisation systématique des concepts), Vrin, Paris, 1966
Moretti, Alessio. The Geometry of Logical Opposition, PhD Thesis, University of Neuchâtel, 2009
Schang, Fabien. 'Abstract Logic of Oppositions', Logic and Logical Philosophy, Vol. 21, 2012: 415-438
Schang, Fabien. 'Logic in Oppositions', in Studia Humana, Vol. 2(3), 2013: 31-45
Smessaert, Hans. 'On the 3D Visualisation of Logical Relations', Logica Universalis, Vol. 3, 2009: 212-231

'What is this thing called Duality?'
Keith Begley (Trinity College Dublin)

I employ the word 'duality' as a technical term of philosophy to refer to binary oppositions in all aspects or domains of reality. Some of these dualities are easily recognisable and others require the formal analysis of a special science in order to be recognised. In this presentation I will briefly outline some of the attitudes taken towards 'opposites' by the special sciences; in particular, the lexical semantics of antonymy, and the psychology of the perception of opposites. I will also look at some proposed philosophical problems involved with these views and engage with the question of the nature and origin of Duality.

'Reality as the Coincidence of Opposites: Alfred North Whitehead on Time and Eternity'
Hannah Haejin Kim (Oriel College, University of Oxford)

Alfred North Whitehead's metaphysical system is a project of complementarity; he sees truth in a series of coincidences of opposites manifested in the creative process, and his treatment of time and eternity is an example of how he integrates traditionally paradoxical notions. In Process and Reality, temporality is both fixed (complete already) and flowing (unfolding successively). Therefore time, eternity, and even everlastingness interpenetrate each other in Whitehead's philosophy. Temporality is one manifestation of the fact that only the conjunction of process and reality adequately captures the true metaphysical arrangement of the world. Whitehead's complementary philosophy is informed by his belief that there is no such thing as an isolated fact in the universe. This sentiment encourages him to incorporate every aspect of reality, including our experiences, to be a meaningful part of the structure of reality. Since temporality is one of the most important tenets of the human experience, Whitehead aims to account for its significance and meaning in a way that preserves the coincidence of opposites present in the universe. Whitehead's philosophy blurs the sharp distinction between temporality and eternity because the 'ideal contrast between permanence and flux' is a 'contrast of opposites whose ultimate harmony is expressive of the organic interconnectedness of the world'.

'Predicating Opposites in Plato's Sophist'
Christopher Buckels (Trinity College Dublin)

The megista genê, or greatest kinds, in Plato's Sophist appear to 'run through' all other kinds. One way of interpreting this discussion is as a theory of predication, since the various kinds are 'said' in different ways. Especially interesting questions in this discussion are whether opposites can be predicated of a single thing and whether a kind can be predicated of its opposite. For example, can something be both changing and at rest, and can change rest and rest change? A standard interpretation of Sophist 254ff. takes it that some kinds may not be jointly predicated, and that some may not be predicated of their opposites: Change and Rest are taken to be paradigmatic examples of these kinds. I will defend an opposing interpretation, which will also involve discussion of how Sameness and Difference are predicated of each other and the other 'greatest kinds', which include the four kinds mentioned as well as Being. In short, I will make use of a distinction in the text between kath hauto (per se or by itself) predications and pros ti (in relation to something) predications to show that Change, Rest, Sameness, and Difference are predicated relationally and are, thus, not incompatible with their opposites when predicated in relation to different things. For example, a woman driving a car is at rest in relation to the car and yet changing (in motion) in relation to her surroundings. A kind may be at rest and changing similarly: at rest in one way and changing in another. Thus opposite kinds may, as a rule, be jointly predicated of a single thing and be predicated of their opposites, as long as they are predicated in relation to different things.

'The Tao of Logic'
Flavio Zelazek (Sapienza - Università di Roma)

In this work are examined the conceptions of duality given in the classic Chinese philosophy and in the recent logical research

From the consideration of the I Ching (Book of Changes) and the T'ai Chi Ch'uan classics emerges a characterization of duality as coexistence, interchangeability and interaction of opposites of the same nature.

A similar conception of duality, at the logical and computational level, arises from the results of linear logic in the Curry-Howard (or Proofs-as-Programs) paradigm: duality is expressed by linear negation, which has a clear computational meaning involving symmetry between inputs and outputs.

A connection with ethics and non-deductive logic is briefly pointed at.

Keywords: duality, interaction, negation, proofs-as-programs, linear logic, I Ching, T'ai Chi Ch'uan

'John Duns Scotus on the Reality of Opposition'
Dónall McGinley (Trinity College Dublin)

This paper is an exploration of John Duns Scotus' account of natural opposition, found in his theory of common natures. Duns Scotus argued that the relata of natural opposition must be common natures rather than individuals. Common natures, on Scotus' view, have a unity less than the numerical unity that pertains to individuals. I will develop Duns Scotus' account of less than numerical unity to argue that a real unity holds between opposites themselves. In addition to this treatment of Aristotelian opposites, I will look at a modal opposition found in Duns Scotus' theory of universals and individuation, and defend it against William of Ockham's charge that it is ultimately self-contradictory. According to Duns Scotus, a thing's nature, while it exists in reality as an individual instance, is nevertheless 'of itself' common. Ockham argued that Scotus' claim that natures are individual in their instances but nevertheless 'of themselves' common is really to assert opposite features of the same thing, and results in a contradiction. Furthermore, Ockham insisted that Scotus' metaphysics explains individuation and distinction by appealing to what is non-intrinsic to the distinguished entities, therefore offending against a central Aristotelian principle. I argue, against Ockham, that Scotus' metaphysics does not appeal to what is non-intrinsic to account for intrinsic features, and that the oppositions found in Scotus' account of common natures and individuation are essential to giving a proper description of the modal features of his theory of universals.