Gautama is the founder of the Nyaya school and the author of the Nyaya Sutra, the greatest text on logical debate of ancient India, and he is also known as Akshapada, (eyes in the feet, or gazes at his feet), which, like Kanada’s name, could mean someone who is gathering up many particular things in the lower world into higher universal concepts, or someone lost in thought, much as Thales, the first famed Greek thinker, was gazing at the stars as he fell into a well.  A legend says that the same happened to Gautama, who fell into a well while lost in thought, so Brahma gave him eyes in his feet.

Nyaya means right, just, justified or justifiable, the same way we use logical to mean justifiable and defendable debate or speech.  The Nyaya school reached its height in 150 CE, but it traces itself back to Gautama and his teachings.  In ancient India, a king, authority or rich patron could organize a debate and banquet, invite participants from various schools of thought to debate.  A story from the period says that a scholar who gave up on the Vedas and turned entirely to logic turned into a Jackal. This story was obviously told by Vedic scholars and priests who found the new systems a threat to the old established traditions.  The other famed Nyaya logicians, each writing commentaries on the Nyaya Sutra of Gautama and the others before them, are Vatsyayana (c. 450 CE), Uddyotakara (c. 550 CE), Vacaspatimishra (c. 900 CE) and Udayana (c. 1000 CE).

The Nyaya Sutra presents many debates that raged at the time, with many centered on dividing the mortal and particular from the eternal and universal, such as whether or not the self, or world, or laws of the cosmos are permanent or fixed in this or that way.  One of these questions, asked previously by Kanada, is whether or not sound is temporary, and Kanada, like a Buddhist, says it is, though Kanada and the Nyaya following Gautama would insist that the self and laws of the cosmos, unlike sound, are eternal, following orthodox, established Hindu positions.  These debates, as well as those about whether or not luxury or pleasure are good or bad, often take the form of a basic bifurcating disjunction: Is A B or not-B? Vedic priests argued that the individual self is eternal, while the Charvakas and Buddhists argued that it is temporary. Buddhists who debated the Nyaya often used relative qualifiers such as A is sometimes B, or A is somewhere B, or A is B in some things, in some ways.

Gautama and the Nyaya base their entire system, which they argue, like the world, is a coherent, positive whole, on one source of knowledge, perception, as the Charvakas do, but they also argue that there are three other sources of knowledge that serve as bases for justifiable positions, beliefs and arguments, inference, as do the Vaisheshika, but also comparison (which some translate as analogy, an extensive comparison) and testimony, like the evidence of a witness in court for something we didn’t see.  Thus, there are four sources (pramana) of knowledge for the Nyaya, but the later three are secondary and inferior to the first, direct experience of what we infer, compare or hear about through testimony of others.

The word pramana, which the Nyaya use for source, foundation, or evidence, means proof, and comes from the word roots for out from (pra) and measurement (ma), such that measuring out things to judge them is talking things out in debate.  The Buddhists refer to it as pramanavada, the way or viewpoint of measuring things out.  The Nyaya argue a proper understanding of the inventory of reality is important to act effectively, assuming reality has an order independent of our minds and cultural practices.  Vatsyayana, the foremost Nyaya logician after Gautama, says that all of the Nyaya method is investigation of subjects by means of sources, and Uddyotakara says the best reasoning involves many sources to establish a position well.

The Nyaya lean towards “innocent until legitimate doubt” about belief, which means they lean towards positive belief, unless things are disproven or there is some evidence against them.  Inferences can be hastily drawn, but if they are drawn slowly, based in good, careful reason, we should entertain them positively and favorably, not as certain but as openly possible. The same is true of perception, comparison and testimony, such that they are overall reliable, if we are careful with them.  If a belief that exists is doubtable, we should investigate it with sources and testing possibilities, using hypothetical reasoning (tarka).  The Charvakas, Buddhists, and other skeptics doubt that conviction and coherence is what we need as opposed to tranquility and perspective.  In the beginning of Vatsyayana’s commentary on the Nyaya Sutra, he argues:

When things are grasped through sources of knowledge (pramana), it is possible to act and succeed.  Thus, sources of knowledge are useful (arthavat). Without sources of knowledge, there would be no successful action… Success is a relationship with its result: gaining or losing things, which could be happiness or sadness, or some way to or from either.  The ends served by sources of knowledge are innumerable, since the living things who use sources of knowledge are themselves innumerable.

When sources of knowledge are connected to things, so are the knower, known and knowledge.  Why? Because without all of these knowledge of things is impossible. Of these, the person who acts with desire or fear is the knower, the way it is known is the source of knowledge, the known is the object, and truthful thought made the right way is knowledge.  Truth is fully grasped when these four are in place.

So, what is truth?  It is the grasping of being in something that is and not-being in something that isn’t.  Grasping what is as what is, and what isn’t as what isn’t, is truth, as it is, unchanging.

How can something that isn’t be grasped through a knowledge source?  At the time something that is is grasped, there is not grasping something that isn’t, like the light of a lamp that shows something that is and so also what isn’t.  We think, if it was there, it would have been seen, but it wasn’t seen, so it isn’t there.

In Through The Looking Glass, Alice tells the White King she sees no one on the road, and the king praises her for having such eyes, seeing no one, and at such distance, which he can’t do.  We can’t see no one, but we can look, and not see anyone, which can be said and understood as seeing no one.  The play on words works in ancient India, Greece, China, and today in modern English.  In Zen Buddhism, Hakuin painted blind men walking carefully on a log bridge several times, as the question had been asked, What does it look like to us that they are blind?  What does it look like to see a rat in a maze, and know it can’t see the way out?  Do you see it? Do you see and feel it? Do you see and feel and imagine it? You likely don’t talk it out much.

Uddyotakara, a later Nyaya logician, says in his commentary that all sources depend on perception, and sources of knowledge give us a true grasp of things, but there are fake sources of knowledge, and acting on a true source of knowledge leads to success, and acting on a fake source leads to failure.  How does failure look, if not like a lack of success, another sort of seeing what you don’t see, or imagined, but did not perceive. The Nyaya Sutra and commentaries tell us that there are problems we can have with the four sources of knowledge, such that we can mis-perceive, and see what isn’t there, or not see what is there, such as unrecognized success or potential talent, even though perception is their primary source, that supports all others insofar as the others are justified.

Perception is seeing or experiencing something for oneself, and can only be valid if it tells you something that doesn’t vary or change.  Three examples of false perception given in the sutra are confusing smoke and dust, confusing a rope with a snake, and thinking that the hot earth is wet when in fact this is a mirage.  There is a popular modern Indian novel about a man in a loveless arranged marriage who falls in love and has an affair with a prostitute called The Rope and The Snake.  Vatsyayana says that some argue that for every thing there is a word and name that is based on conventional practices (vyavahara), and so perceptual thinking is verbal in nature, but this is a mistaken view, seeing words where they aren’t there, as we can look at an object without knowing its name, so perceptual understanding is not dependent on language. (10.11 – 20)  His view is remarkably similar to Wittgenstein.

Vatsyayana argues that we can see what we think is smoke and infer there is fire, or hear that there is a fire by testimony, or make comparisons for ourselves from afar, but it is perception, seeing the fire, that is best and that best confirms comparisons, testimony and inferences.  Giving a negative example, he similarly argues that seeing a mirage and hoping for water, it is only when we see what isn’t there, the water’s absence, that our inference is disproved. We can also make solid inferences, such as hearing thunder and inferring there was lightning, without making comparisons or hearing the testimony of others.

With knowledge, perception is best.  When we learn something from trustworthy testimony, we may still want to know it another way, such as by inference.  Understanding by inference, we may still want to know it through experience, but seeing it, the desire to know ceases, as in the example of fire above.

Vatsyayana explains comparison with the example that yak is like a cow, and this is sameness understood in terms of universals, classes of things with shared properties, such as having horns, or having four legs.  Comparisons can be valid or invalid, depending on whether or not they are supported by inference, testimony, and of course, perception. Testimony, like perception and the rest, can be valid or not, as we all know from personal experience.  Sometimes witnesses lie, and other times they are mistaken, either seeing what they couldn’t have, or not seeing what they could have. There is a psychology experiment that is somewhat well known where a video is shown to subjects of a line at a bank, a shot goes off, and everyone scatters, and some say they see a gun, some say the black guy in line had a gun, and there is no gun, showing racist bias, but also our ability to construct false memories, which can easily become false testimony.

Vatsyayana says inference is the source that comes last, after experience involving perception, analogy and testimony.  The Sutra says inference depends on previous perception and is of three types: from something prior, something later, and from something in common.  Vatsyayana gives an example of each. If we see swollen storm clouds and infer it will rain, we infer from something prior, inferring an effect from a cause prior to it.  If we see an overflowing river and infer it rained up stream, we infer from something later, inferring a cause from the effect later to it. If we infer that the sun was in one place and now another in the sky, we can infer that it moved, as a difference between the two.

The Sutra says (1.1.41) that certainty is grasping something by thinking about possibilities, investigating thesis and counter-thesis, and that the sources can be objects of knowledge themselves, like a measuring scale.  Vatsyayana adds that a scale can calibrate a second scale if we weigh gold with the first and then with the second, such that we know the second scale is off or not. Thus, we can use a tried and true knowledge source, like watching with our eyes, to test another knowledge source, like a theory we find in a text or the testimony of witnesses.

The Sutra says that critics (such as Jains and Buddhists, we imagine) could say this leads to an infinite regress, such that no source can be entirely established by other sources.  Consider that the first scale could be off, which would mean we can’t use it to check against a second, but where do we know a scale is good without checking it against another? The answer for the Nyaya is that evidence is like the light of a lamp, self-evident in itself, leaning towards positive belief of what seems consistently true as establishing itself as true without controversy.  The Nyaya Sutra says sometimes no further source is required, sometimes there is, and there is no fixed rule for determining this. (2.1.20) Because we, like Hindu Nyaya, seek freedom, discipline, pleasure and wealth in this proper descending order of importance, we proceed from what is to what we desire which isn’t.

The Sutra says that opponents argue that objects are like dreams, mirages, or magic cities in the sky, not fixed as real, and says that they haven’t provided a reason to accept this.  Vatsyayana says when we wake, we see with perception that the dreams weren’t real, which shows us perception and illusion are different. A Buddhist could object that they are making a comparison, a valid source of knowledge.  The Nyaya would argue that perception is primary and more certain than comparison, such that physical objects are like mirages, but not entirely, as they are better established. But how can we say this without making a comparison to check, just as we are checking perception against comparison, with comparison, right now?

The Nyaya Sutra says that words are used to refer in three ways, to individuals, forms, and classes, and these multiple ways produce doubt, which sparks inquiry. (2.2.59)  Vatsyayana provides us with the example of cow, and says the word refers to an individual cow, and anything shaped like a cow (to use the word metaphorically, as cow-ish-ness), and the class of all cows, which the Nyaya argue all have horns and four legs, like other classes of animals, forms of animals and individual animals.  Vatsyayana says that the object of the word is thus determined by our ability to use it in these ways. The Sutra refutes those who think words refer to only one of these things, simply individuals, or simply forms, or simply classes, and says the meaning of a word is clearly all three of these uses.  The Sutra uses the example of a clay cow, which has the form of a cow, and is included in classes such as things that have four feet, like a cow, but as Vatsyayana adds, if someone says to wash, bring or donate a cow, and we hand them a clay cow statue, we are wrong, and do not satisfy their requests, as it lacks the category of being alive, or an animal at that, so it is certainly the wrong sort of individual.

Debate manuals like the Nyaya Sutra of Gautama, the Organon of Aristotle and works by Moists in China were designed to introduce students and scholars to forms of argument, methods of attack and defense.  Like Aristotle, Vatsyayana argues that debate proceeds from motives, and so a destructive skeptic debates destructively, without a committed motive or acceptable doctrine. Some have claimed that Aristotle’s syllogisms are deductively valid but Gautama’s syllogistic form of proof is not and based on induction.  Actually, Aristotle has many syllogisms he openly admits in the text are not deductively valid on their own, and those forms, unlike the perfect four, weren’t studied by Islamic or Catholic logicians much. We can see induction and deduction working together in the syllogistic forms of both Aristotle and Gautama, and the similarities are quite striking.  There are five formal steps to the Nyaya formal proof, but as Buddhists later perceived the first and second steps are identical to the fifth and the fourth, and can be eliminated.

To make each form of proof easier to study, I take liberties with both the Indian and Greek syllogistic forms, preserving the information but changing the order it is presented to show how the information connects in sequence.  Strangely, in the original texts of Aristotle, the most famous and basic form of syllogism is not If A then B, if B then C, so if A then C, as I present it, but rather In B then C, if A then B, so if A then C, such as Aristotle’s famous example, All men are mortal, Socrates is a man, so Socrates is (or rather, was) mortal.  It does work, but it works better as Socrates is a man, all men are mortal, so Socrates is mortal.

Similarly, Gautama’s central example is, Wherever there is smoke there is fire, as in a kitchen,  so because there is smoke on the hill, there is fire on the hill.  This is almost identical to Aristotle if we change the subjects to his, and say, Whoever is a man is moral, like Plato, so since Socrates is a man, Socrates is mortal.  Thus, we can reorder Gautama’s proof in a similar A to B to C way, such that it reads, There is smoke on the hill, wherever there is smoke there is fire, as in a kitchen, so there is fire on the hill.  Notice that this is not perfect, because perception of smoke is a central example of possible misperception, but it need not be, as smoke can look quite dissimilar from a dust cloud sometimes.  The second example would then read, in line with Kanada’s cosmic observations, Sound is made, and whatever is made is impermanent, like a pot, so sound is impermanent.  Those who say Gautama relies on induction focus on the addition of the extra example offered, and not on the clear similarities of the forms.

The Nyaya Sutra also lists fallacies, forms of mistakes in debate that sound solid but have flaws, much as the Nyaya say we could see a post in the dark and mistake it for a man.  The Sutra warns us, much like Aristotle, that debate is about winning, but if we make arguments that are faulty, called clinchers by translators, cheap-shots, and if we point out faults that aren’t there in our opponent, called quibbles, nit-picking, we risk losing the debate if anyone notices, and we shouldn’t make them in the first place if we want to not only win, but be right.

For fallacies, the Sutra includes silence (which would lose a debate indeed), changing the thesis, contradicting the thesis, evasion (in one commentary, it is translated, I am called by nature… and then, we hear screeching tires outside), meaningless or incoherent speech (Chomsky gave the example for linguistics of Colorless sleep furiously green, which he thinks is meaningless), repetition (rather than additional argument where it is needed), overlooking the fallacies in an opponent’s argument (which could be pointed out by others), and my personal favorite, sharing the fault, pointing out a fault in an opponent that is also a fault in one’s own argument, or a fault in everyone (such as, My opponent is putting forward a mere mortal point of view).

The Sutra gives three types of quibbling, which correspond to the three uses of words, thing, form and class.  Vatsyayana give us examples for each, as he does with his commentary for everything in the Sutra.  For quibbling over words used for things, he says someone could say they had a new (nava) blanket, and someone else could misunderstand the individual word and think they claimed they had nine (also nava) blankets, and point out the false fallacy.  For quibbling over form, someone could say, The stands cry out, and someone could foolishly say that stands can’t cry, as they don’t have feelings, but they are wrong.  I have mistaken this for scaffolds, and thus the hangman rather than parade crowds, due to an earlier translation.  For quibbling over class, someone could say, All Brahmins are educated, possibly to construct an example of a Nyaya syllogism for your assignment, and someone else could wrongly object, Not all Brahmins are educated, because some are only three years old, and just learning to talk!