Étienne Gilson (1884-1978), a scholar of Medieval ages who shows much interest in Medieval philosophers, especially in Thomas Aquinas, in his famous work, Being and Some Philosophers, gives an account of the views of Ibn Sina as a philosopher whose thoughts were highly influential in Middle Ages and and criticized several problems of his philosophy including unconditioned quiddity, addition of existence to quiddity , essential contingency and principle of causality. According to Gilson unconditioned quiddity is inconceivable. The problem of existence as additional to quiddty is also more a matter of religion than that of philosophy. Essential contingency is a contradictory assumption and the principle of causality leads to unfree-will of God Almighty.
The present article is to give first an account of what Gilson understands to be Ibn Sina's views in each problem and then deals with criticisms of Gilson which in his view challenge the ontology of Ibn Sina. Finally a critical analysis of Gilson's views as well as his critiques will be given.
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