modality and temporality: ibn sīnā’s theory of modality revisited

The theory of modality is the matter that most clearly manifests the impact of ibn sīnā (d. 428/1037), the most influential philosopher in the history of islamic logic. ibn sīnā states on the one hand consistently that there are three fundamental modes as necessity, impossibility and possibility in his works; on the other hand, he adds the mode of continuity and discontinuity to the theory of modal logic and classifies the propositions both in terms of being necessary-possible and being continuous-discontinuous. this very situation resulted in the possibility of ibn sīnā’s general absolute propositions to mean continuity-discontinuity as well as necessity-possibility. therefore, in modern studies of islamic logic, it has been widely accepted that one of the most critical points in which ibn sīnā differed from aristotelian logic and latin logicians was his understanding of general absolute propositions. the primary aim of the present paper is to answer the questions of (i) why ibn sīnā felt the need to include temporal propositions in his system, and (ii) whether his attitude represents a fundamental departure from aristotle’s fundamentally essentialist/alethic modal logic to an essentialist-temporal modal logic. by answering these questions, it is aimed to open up for discussion the accuracy of contemporary interpretations that contrary to aristotle’s essentialist modal logic, ibn sīnā developed a detailed essentialist-temporal logic system. the illumination of these issues provides us with some crucial clues in terms of clarifying both the nature of ibn sīnā’s modal logic and the approach of post-avicennian islamic logicians -mainly because they remained within the understanding of modality laid by ibn sīnā- to modal logic. to this end, essentialist-temporal explanations included in ibn sīnā’s logic books were brought together and analyzed in a holistic way. in addition, fakhr al-dīn al-rāzī (d. 606/1210) and afḍal al-dīn al-khūnajī (d. 646/1248) comments on ibn sīnā’s essentialist-temporal explanations were also considered. the main claim of this presentation is that although as a result of the understanding of five universals ibn sīnā inherited from porphyrios (d. 305), ibn sīnā examines three discontinuous necessary propositions and these discontinuous necessary propositions led to temporal other explanations such as continuous necessary propositions, general absolute propositions which are probable to be discontinuous and “perpetual (dāima)” propositions as contradictions of general absolute propositions, ibn sīnā has an essentialist modal logic understanding and his temporal explanations in the context of general absolute and modal propositions are only tools of his essentialist modal logic system.