Sufficient reasons grounded in the Principle of the Best look outside the concept of the subject and make comparisons between possible worlds in terms of relative perfections.

In some texts, Leibniz suggests that the sufficient reason for contingent truths cannot be found in the concepts or natures of things. We must instead look to the Principle of the Best (Mon. 36–38/G VI, 613). In other words the sufficient reason for any contingent proposition of the form “a is F” is that a is F is true in the best possible word. This appears to be an entirely different sort of reason than the fact that “a is F” is analytic or that the nature of a determines that it is F. Those r