 The second way of associating the principles with specific domains is to specify the domain of truths that is grounded on or depends on each principle. According to Leibniz, only contingent truths depend on and are grounded by the PSR. Likewise, Leibniz believes that only necessary truths depend on and are grounded by the Principle of Contradiction. What does it mean for some truths to depend on a principle? Leibniz is not explicit on this point but we will get a better idea in the next section when we consider the question of what counts as a sufficient reason.