The use of analogies or examples can be found in almost any philosophic tradition. Nyaya and Mimamsa are the two main Indian schools noted for their acceptance of upamana or knowledge through analogy, and this book meticulously traces the ways in which they have handled the status of analogy as a source of knowledge. Within Nyaya, Chattopadhyay seems to follow Gautama's account of upamana as knowledge of the relation between words and their meanings; this relation, in Nyaya thought, is based on similarity between the word and the object.
As for Mimamsa, the author shows how that school's sense of upamiti, knowledge of similarity, in cases where we see similarity between a thing we know and one we encounter for the first time differs from instances where we see similarity between a thing which is present to our senses and one which is not. In the latter case, if we learn the similarity by being told about it, then questions arise over the status of knowledge by verbal testimony. Nyaya school, for its part, accepts such knowledge as contributing to upamana, though that acceptance opens Naiyayikas to the criticism that in effect they abandon the idea that upamana has a distinctive character.
In the ensuing arguments, both Bauddha and Vaisesika thinkers object to the status of upamana as what Chattopadhyay calls ‘cognition', or a genuine source of knowledge, equal in status to perception, inference, and verbal testimony. One objection is that similarity cannot obtain over and above pairs of objects that resemble each other, which means that if one of the pair is absent then there can be no experience of upamana; this applies to both Nyaya and Mimamsa thought.
The objection, however, holds only if we accept that upamana can obtain solely when its objects are present to the senses, a position reminiscent of Bertrand Russell's requirement that objects be present when we speak of them, even though Russell posits that requirement as, more than anything else, a condition of the intelligibility of what we say.
Needless to say, Mimamsakas have responded to the challenges, and Chattopadhyay handles the metaphysics with care. One response identifies a special sense of upamana for cases where one of a pair of objects is not present; in such cases sadrsya or similarity is acceptable as upamana because the absence of a thing we have perceived differs from the absence of a thing we have never perceived.
Chattopadhyay then examines the Nyaya insistence that upamana is self-subsistent as a source of knowledge. Bauddha thinkers particularly resist upamana as knowledge of the word-meaning relation, because this can imply that the relation is an independent entity between the word and its meaning. That creates the further risk that we need another relation to connect the relation itself to each of the substantive terms; that, as Russell also sees, opens an infinite regress.
Other difficulties are raised by Vaisesikas, who contend that knowledge by analogy is knowledge by inference, as it can be conveyed only by reliable testimony, or by perception of analogy, or by recollection of reliable testimony. These passages cover work by many thinkers over a long period, and provide reminders of other traditions. For example, the transformation of non-recollective awareness into inference is evocative of the Meno, where Plato's Socrates tries to show that knowledge is ultimately recollection.
Nyaya accounts of upamana have, like the Mimamsa ones, progressed in response to objections, as Chattopadhyay shows. She concludes that upamana, though apparently dishonoured by rejection, has in fact been honoured by the attention Indian philosophers have given it. This most accomplished work could well provide a basis for further inquiry. For example, the denotational or referential theories of meaning which occasionally figure in the book could face objections in Indian philosophy and in other traditions that have identified the incoherences in empiricism and positivism. There could also be objections to the Nyaya insistence that any term has a core meaning.
Other investigations for which this book might form a starting point are those of the purpose of analogy in philosophy, and of what it is to see an analogy. One question arising from it is that of what is conveyed by the dawning of an aspect. The thinker associated with that, namely Wittgenstein, however, uses that question in his later work to show the risks of the compulsion to propound or impose taxonomies or schemata in, or on, philosophic inquiry.
If the schools examined here sometimes incur such risks, Chattopadhyay has shown the significance of the issues they address and of attending to the differences between them — in sum, the importance of attending — and has thereby performed a notable service.