Nyāya Sūtras 2.19

2.19

pratyakṣāgamāśritam anumānam, sānvīkṣā/ pratyakṣāgamābhyām īkṣitasyānvīkṣaṇam anvīkṣā/ tayā pravarttata ity ānvīkṣikī --- nyāyavidyā --- nyāyaśāstram/ yat punar anumānaṃ pratyakṣāgamaviruddhaṃ nyāyābhāsaḥ sa iti/

Inference based on perception and testimony is 'critical scrutiny' (anvīkṣā). Scrutiny (anvīkṣā) is the re-examination of an object already examined by perception and testimony. Because it proceeds by means of that, it is 'critical inquiry' (ānvīkṣikī)—the science of reasoning, the treatise on reasoning. But an inference that contradicts perception and testimony is a pseudo-reasoning.