The Nyaya theory of inference is a significant aspect of Indian philosophy, particularly within the Nyaya school of thought.
Developed by philosophers like Gautama (also known as Akṣapāda Gautama) and his followers, Nyaya provides a systematic framework for logical reasoning and inference.
At the core of Nyaya epistemology is the concept of knowledge (pramāṇa), which refers to valid means of acquiring true knowledge about the world. Nyaya recognizes four primary sources of knowledge: perception (pratyakṣa), inference (anumāna), verbal testimony (śabda), and analogy (upamāna).
Inference (anumāna) is considered one of the most reliable sources of knowledge according to Nyaya. It is a process of arriving at new knowledge by drawing conclusions based on existing knowledge. The Nyaya theory of inference provides a detailed account of the structure and types of inference.
The Nyaya theory of inference consists of five steps, known as the five members (avayava):
- Pratijñā (proposition): This is the initial claim or thesis that is to be proven or established through inference. It can be in the form of a categorical statement such as “All S is P” or a conditional statement such as “If A, then B.”
- Hetu (reason): The hetu is the reason or middle term that serves as the basis for the inference. It is the essential characteristic or mark that is present in the hetumāna (subject of inference) and absent in the sādhya (probandum, the object of inference). The hetu connects the pratijñā and the sādhya.
- Udāharaṇa (example): The udāharaṇa provides an example or instances where the hetu is present and the sādhya is absent. It serves as an illustrative case that demonstrates the relationship between the hetu and the sādhya.
- Upanaya (application): Upanaya involves the application of the hetu to the subject of inference (hetumāna) in order to establish the connection between the hetu and the sādhya. By showing that the hetu is present in the hetumāna, the inference concludes that the sādhya is also present.
- Nigamana (conclusion): Nigamana is the final step of the inference. It is the logical conclusion drawn from the application of the hetu to the subject of inference. The conclusion affirms the sādhya based on the presence of the hetu in the hetumāna.
The Nyaya school recognizes different types of inference, including inference for oneself (svārthānumāna) and inference for others (parārthānumāna). Inference is further classified into three main types: inference based on perception (anumāna from pratyakṣa), inference based on verbal testimony (anumāna from śabda), and inference based on analogy (anumāna from upamāna).
Overall, the Nyaya theory of inference provides a logical and systematic framework for drawing valid conclusions based on evidence and reasoning. It emphasizes the importance of evidence and logical consistency in acquiring knowledge and understanding the world.