There has been a rich history of debate between Vedantists and Buddhists.
One main method the Vedantist uses disprove every other sect which doesn't hold Vedas as true, is to first prove that Vedas are authorless, then say that authorless Vedas have to be 100% true because the defects of lies and incomplete knowledge cannot be there in authorless, and therefore that whatever in Vedas must be 100% true and any sect which goes against the Vedas must be false. These are the two steps
- Apourusheyatva (Authorlessness)
- Swayam Pramanya (Default Validity)
I have heard that various Buddhist scholars like Dharmakirti etc have tried to refute the claim of authorlessness of Vedas and its validity. Supposedly one such argument is there in first chapter of Pramanavarttika, which I couldn't find.
The first chapter discusses the structure and types of formal inference and the apoha (exclusion) theory of meaning. Dan Arnold writes that apoha is: "the idea that concepts are more precise or determinate (more contentful) just to the extent that they exclude more from their purview; the scope of cat is narrower than that of mammal just insofar as the former additionally excludes from its range all mammals in the world that are not cats." In the latter half of this chapter, Dharmakīrti also mounts an attack on Brahmanism, the authority of the Vedas, Brahmins and their use of mantras, and the system of caste (see Eltschinger 2000). He also discusses the role of scripture, which he sees as fallible and yet important for their discussion of “radically inaccessible things” (atyantaparokṣa) such as karma. Dharmakirti critiques the Brahmins thus:
"The unquestioned authority of the Vedas;
the belief in a world-creator;
the quest for purification through ritual bathing;
the arrogant division into castes;
the practice of mortification to atone for sin—
these five are the marks of the crass stupidity of witless men."
So -- what were Buddhist arguments against Vedic validity because of its authorlessness?
I'm interested in logical syllogism of Dharmakirti and the like -- in response to the authorlessness of Vedas.
Edit -- My question is specific: Vedantists have given a syllogistic argument to prove that the Vedas are authorless, and many eminent scholars of Buddhism like Dharmakirti etc have tried to refute those syllogistic arguments by logic ... what are those arguments? Please don't answer this question in a general or a philosophical way.