正理论，梵文 Nyāya，意译为 “法”、“规则”，古印度六派哲学之一，由婆罗门阿克沙巴德·乔达摩(足目·瞿昙?)Akshapāda Gautama（公元一世纪）所创立，其理论的某些方面跟胜论（Vaishéshika）相似。其理论为乔达摩所着的《正理经》（Nyāaya-sūtra），它使之前的印度逻辑变得系统化。该正理由此步入一个新阶段，即新正理（navya-nyāya）阶段。著名《如意宝真相》（Tattva–cintāmani）作者甘给沙（Gangesa）为此经作了注释（12世纪）。

Nyāya (Sanskrit: न्याय, ny-āyá), literally means "rules", "method" or "judgment". It is also the name of one of the six orthodox (astika) schools of Hinduism. This school's most significant contributions to Indian philosophy was systematic development of the theory of logic, methodology, and its treatises on epistemology.