It has been pointed out that Śaśadhara, who was active in the 14th century, greatly influenced Gaṅgeśa (ca. 14th c.), i.e., the consolidator of the Navya-nyāya school, who is a predecessor to or contemporary with him. To construct the early history of this school, we must investigate Śaśadhara. Among various philosophical concepts, I focus upon that of cause and analyzed the “Cause-ness Chapter” (Kāraṇatā-vāda) of his Nyāya-siddhānta-dīpa. Based upon his discussions of five provisional definitions and three conclusive ones, I clarified the characters of those conclusive ones. The first two definitions are for a cause which produces its effect; the third is for a cause which does not produce its effect. For him the first definition is the simplest; the second and third are correct from the logical point of view.
