Avicenna and the Principle of Sufficient Reason

Abstract

The TERM, PRINCIPLE OF SUFFICIENT REASON (hereafter, PSR) was coined by Leibniz, and he is often regarded its paradigmatic proponent. But Leibniz himself often insisted, he was by no means the first philosopher to appeal to the idea that everything must have a reason. (1) Histories of the principle attribute versions of it to various ancient authors. (2) A few of these studies include, or at least do not exclude, medieval philosophers; one finds the PSR Abelard, another finds it Aquinas. (3) And while Leibniz retains pride of place these histories, Spinoza is sometimes said to precede him in appreciating the importance of the Principle and placing it at the center of his philosophical (4) In this paper, I shall argue that the same should be said of the Islamic philosopher Avicenna. Writing six hundred years before his early modern counterparts, Avicenna routinely and consistently appeals to the PSR generating his metaphysical system. The paper aims first to establish that Avicenna deserves a position of prominence histories of the PSR ([section] 1), and then to consider how he addresses certain challenges to the PSR, especially the threat posed by necessitarianism ([section] 11). Some contemporary philosophers argue that the PSR entails necessitarianism and thus conflicts with the intuition that things could have been otherwise. (5) That the PSR entails necessitarianism is judged to count against the PSR. To consider Avicenna's response to this threat is important: it not only helps us understand the nature and extent of his commitment to the PSR but also helps us assess the PSR itself. I will argue that Avicenna disputes the veracity of the intuition that things could have been otherwise by showing that it may be rooted ignorance of the determining causes of some events. I will also argue that Avicenna's modal ontology calls into question the view that the PSR entails necessitarianism. The paper's initial aim--namely, to establish that Avicenna deserves a position of prominence histories of the PSR--is important for three reasons. The first of these is historical accuracy. The PSR is sometimes said to be as old philosophy. (6) It has played a supporting role several major philosophical systems. Its truth, its implications, and its pemiciousness remain a subject of philosophical debate. An adequate history of philosophy requires an accurate history of the PSR. A second reason has to do with the relationship of the PSR to rationalism. Commitment to the PSR is considered a hallmark of rationalism. (7) And rationalism is closely associated with seventeenth-century European philosophers. Indeed, the thoroughgoing rationalism of Spinoza and Leibniz is sometimes thought to distinguish them from their predecessors, whether ancient or medieval. Avicenna, by contrast, is still too often deemed an Eastern or mystical philosopher. Showing that Avicenna no less than Spinoza and Leibniz places the PSR at the center of his philosophy may help establish that familiar but inaccurate divisions the history of philosophy require revision. (8) A third reason has to do with the possibility of historical influence. My discussion of Avicenna's commitment to the PSR focuses primarily on its role the Metaphysics of the Shifa', his philosophical magnum opus. This work offers the most detailed and sophisticated version of his metaphysical system. It was read Arabic and Hebrew by medieval Jewish philosophers, and it was translated into Latin the twelfth century. Our knowledge of the reception of the Metaphysics of the Shifa' is not extensive, but it is already clear that its account of God and its theory of causation influenced diverse authors both the Hebrew and Latin traditions, including Moses Maimonides, Thomas Aquinas, and John Duns Scotus. (9) While this paper will not attempt to demonstrate historical influence, readers of Spinoza and Leibniz will find some Avicennian doctrines discussed the paper very familiar. …