 Tibetan authors define their position—in some cases a provisional one adopted as a mere interpretative tool for dealing with Dharmakīrti’s texts—on the basis of models associated with Indian Buddhist schools. A fourfold typology of philosophical tenets is set forth along two lines of distinction. The first separates external-realist positions from idealist (Vijñānavāda)ones; the second separates representationalist positions from non-representationalist ones. External-realist models agree in positing the existence of extra-mental entities, but differ in their account of the way that a cognition of such objects takes place. According to the non-representationalists (commonly associated with the views of the Vaibhāṣika school), extra-mental entities exist simultaneously to their cognition and are cognized directly by the latter. According to the representationalists (associated with the Sautrāntika school), extra-mental entities are the cause of their cognition but, being momentary, they have ceased to exist at the time cognition arises. 