This text presents a discussion and an evaluation of Leibniz's contribution to the discussion of the problem of freedom and determinism with special reference to earlier contributions by both Aquinas and Molina. Leibniz clearly states that his solution is a synthesis of Aquinas' and Molina's views and yet Leibniz scholars often merely make a passing comment to Leibniz's views in relation to these two philosophers. This text aims to expose and discuss the specific details of these philosophers from whom Liebniz claims to have borrowed a few ideas. The text draws the conclusion that although Leibniz's solutions of the problem of freedom and determinism is incompatible with some aspects of his metaphysics, its is nonetheless a philosophical advance from both Aquinas and Molina's positions.