the universe must be necessary. Al-Ghazali disputed this as incompatible with the concept of God's untrammelled free will as taught in Al-Ghazali's Asharite theology. He further argued that God's free choice can be shown by the arbitrary nature of the exact size of the universe or the time of its creation. Peter Adamson offered several more possible lines of criticism. He pointed out that Avicenna adopts a piecemeal approach to prove the necessary existent, and then derives God's traditional attribute from it one at a time. This makes each of the arguments subject to separate assessments. Some might accept the proof for the necessary existent while rejecting the other arguments; such a critic could still reject the existence of God. Another type of criticism might attack the proof of the necessary existent itself. Such a critic might reject Avicenna's conception of contingency, a starting point in the original proof, by saying that the universe could just happen to exist without being necessary or contingent on an external cause. Classification German philosopher Immanuel Kant (17241804) divided arguments for the existence of God into three groups: ontological, cosmological, or teleological. Scholars disagree on whether Avicenna's "Proof of the Truthful" is ontological, that is, derived through sheer conceptual analysis, or cosmological, that is, derived by invoking empirical premises (e.g. "a contingent thing exists"). Scholars Herbert A. Davidson, Lenn E. Goodman, Michael E. Marmura, M. Saeed Sheikh, and Soheil Afnan argued that it was cosmological. Davidson said that Avicenna did not regard "the analysis of the concept necessary existent by virtue of itself as sufficient to establish the actual existence of anything in the external world" and that he had offered a new form of cosmological argument. Others, including Parviz Morewedge, Gary Legenhausen, Abdel Rahman Badawi, Miguel Cruz Hernández, and M. M. Sharif, argued that Avicenna's argument was ontological. Morewedge referred to the argument as "Ibn Sina's ontological argument for the existence of God", and said that it was purely based on his analytic specification of this concept [the Necessary Existent]." Steve A. Johnson and Toby Mayer said the argument was a hybrid of the two. References Footnotes Bibliography Preliminary proof is available at McGinnis' website. Arguments for the existence of God Avicenna