Indian Syllogism

Richard P. Hayes rhayes at UNM.EDU
Thu Mar 9 18:02:17 UTC 2006

On Wed, 2006-03-08 at 12:48 -0500, Shyam Ranganathan wrote:

> So, which is it? Could the argument over whether it is deductive or inductive be
> merely a word game, where each measures the argument in a different way (some
> counting the process of hypothesis formation as part of the inference, while
> others include it outside)? Doesn't this mirror the argument over whether the
> vyapti is part of the Nyaya inference or not?

Yes, you have captured the debate precisely. Like you, I don't think
this is a word game at all. Over the years, however, I have noticed a
slight shift in the definition of inductive argument. When I was a young
pup, I was taught that an inductive argument is one in which a
generalization is formed from particular observations. Now, as an old
dog, I teach the young pups in my classes that an inductive argument is
one that is not deductive in nature, but one that nevertheless offers a
good reason to believe a conclusion on the basis of evidence. Deductive
arguments are valid or invalid; and valid arguments are sound or
unsound. Inductive arguments, on the other hand are strong or weak.

When I first started writing about Buddhist logic, I was using such
terms as "valid" and "sound" to refer to arguments that the Buddhists
called "good" or "correct" (samyak). At the time I was taking a graduate
course in philosophy of logics, and my professor, Hans Herzberger,
warned me off using the terminology of deductive logic when writing of
Dignāga. He demonstrated that an argument considered "correct" by
Dignāga could still yield a false conclusion. The failures all stemmed
from making new empirical discoveries. For example, if a North American
has repeatedly observed that all mammals give live birth to their young,
it would be considered a "correct" argument to conclude when one sees a
mammal, that the animal gives live birth to its offspring. If one were
then to visit Australia and see one of the mammals there than lays eggs,
one's previously "correct" argument would yield a false conclusion. This
is something no deductive argument can do. (Do Australian human beings
give live birth or lay eggs? Never having been south of the equator, I
remain agnostic on this matter.)

> To complicate things, inductive arguments seem to fail the criterion
> of deductivety, but seem ok altogether.

Right. Almost all the arguments that we make in daily life are, in fact,
pretty much like the canonical arguments used in classical India. The
classical Indian inferential schema works beautifully in practical life.
Like life itself, it has risks, but one learns to minimize them by
careful empirical observation. The deductive argument, on the other
hand, is rather barren and uninteresting. It works only when the major
premise is analytic. How often are we called upon in real life to make
inferences about the marital status of bachelors? 

> Thus, I suggest to determine whether the Nyaya scheme is deductive or inductive,
> we need to not evaluate it from the perspective of our ideal of deductivity, but
> from how they regarded their arguments. Did they see it as yeilding apodictic
> necessity? Or did they regard it in some other fashion. My suspicion is the
> former, but I'm no expert in Nyaya logic.

For a long time I have tried to discuss Indian inferential schemata in
their own terms. One imposes unrealistic expectations on them when they
are called deductive. They just end up looking like failed deductive
arguments. A hundred years ago or so this "failure" was seen by some as
evidence that the philosophers of classical India were substandard
logicians. If one sees Nyāya as trying to present an Aristotelian
syllogism, then the Nyāya inferential scheme ends up looking like a
rather poor, at at least clumsy, attempt at a syllogism. If, on the
other hand, one looks at what the Indians were actually trying to do in
anumāna theory, it turns out they were doing an excellent job at
practical reasoning. 

I see it, therefore, as a practice in charity of interpretation to see
the classical Indians as offering something more like Peirce's abductive
logic (or inference to the best explanation) than something like
mathematical deduction or Boolean algebra. Perhaps this is caving in to
political correctness of some kind, but I do think there is rather more
at stake here than politesse. (I hope so; I'm a complete failure at
being polite.)

Richard Hayes
Department of Philosophy
University of New Mexico

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