I was thinking about Navya-Nyāya syllogisms this morning. Navya-Nyāya is a highly methodical school of Indian philosophy, with a very sophisticated epistemology. They are most famous outside of India for their method of argument. The ideal argument, so it is said, has several steps. In the most common example given:
(1) Pratijñā: There is fire on the hill.
(2) Hetu: Because there is smoke on the hill.
(3) Udāhārana: Smoke goes with fire, as in a kitchen.
(4) Upanaya: Similarly for the hill.
(5) Nigamana: Therefore there is fire on the hill.
What is often not stated in describing this is that this is not some random pile of things thrown together, but that the Navya-Nyāya claim that this line of inference is the most powerful kind of inference has some philosophical backing. The Navya-Nyāya school argues at length that there are four and only four sources of knowledge: Śabda, which is acceptable testimony; Anumāna, which is rational inference; Pratyakṣa, which is perceptive sensation; and Upamāna, which is recognition of analogy or similarity. The 'syllogism' above constitutes a clear interweaving of all four sources of knowledge: we have testimony (1) backed by inference (2) which is confirmed by sensible example (3) and shown relevant by analogy (4); therefore in reaching the conclusion (5), we have done our cognitive utmost, building on the full extent of our ability to come to know anything. It's actually more complicated than this; each step has a set of rules that have to be met and errors that have to be avoided. But if these are met in a given case, the reasoning is powerful; and, if one grants certain basic assumptions about cognition, the conclusion that this is powerful reasoning is exactly right.
What struck me is that, despite the extraordinary rationality of the approach, and despite the common practice of calling this a 'syllogism', this is not a formal inference but a material one, and that Navya-Nyāya logic is actually a canonic. I've talked about canonic before. Putting the point in very crude form, in the Hellenistic period, in the disputes between the Stoics and the Epicureans, the Stoics championed (formal) logic. But of course they would: the Stoics held that the world was pervaded by reason, and that divine reason was involved in everything, so it was natural for them to hold that logic yields knowledge. But if you're Epicurean, you believe that the world is not pervaded by reason but simply a particular combination of ever-shifting indivisibles; so why would you think that logic gives anything more than verbal game-playing? Thus the Epicureans had instead of logic an experience-based canonic. In the post just linked I proposed that empiricist-leaning schools of thought develop a canonic when faced with very strongly rationalist-leaning schools of thought; this seems confirmed by several examples in Western thought. But if the Navya-Nyāya are rightly characterized as providing a canonic, it is massively more sophisticated than anything I have ever seen attributed to Epicureans on the subject, but it doesn't really seem to make much sense at all to characterize Navya-Nyāya as empiricists facing down strong rationalists. So perhaps we should really regard canonic as the natural reasoning-art of humanity, and ask instead how logic takes a firm hold. After all, it does seem we could do just fine in practical life without formal logic, and while the developments of the Navya-Nyāya school are massively more sophisticated than most other canonics, they show just how much you can do with a canonic. On the other hand, perhaps the real issue is not canonic and logic in themselves but the opposition. Navya-Nyāya canonic is not inconsistent with formal logic, nor is it conceived by the Navya-Nyāya school in any way that would lead one to think that canonic is being proposed as importantly superior to formal logic; in fact, at some points the classical texts of the school do seem to get into purely logical considerations, although they don't emphasize them in the way a Stoic or Aristotelian would, and contemporary logicians influenced the school are constantly exploring these and looking at the possibility of formalizing other parts. But Epicurean or early modern instances of canonic certainly do present some kind of opposition; and it is perhaps here that explanation of strong empiricism vs. strong rationalism becomes important, because while it can have some kind of interpretation of formal logic, strong empiricism can't have a major emphasis on formal logic as telling us anything about the world (as opposed to say, telling us how language works): it has no way of grounding the strong modalities (necessity, universality, etc.) that such an emphasis requires.
