FLM 25(2) 6/18/05 2:57 PM Page 26 SECONDARY SCHOOL STUDENTS’ MATHEMATICAL ARGUMENTATION AND INDIAN LOGIC (NYAYA) BRUNO D’AMORE Over a long period of time, I have been observing students known that in India a philosophical doctrine called nyaya (in involved in demonstrating theorems. [1] The demonstrations Sanskrit) opposed the classic Buddhist school. (Nyaya liter- were intended to be individual activity, but were carried out ally means logic, so it is redundant to call the logic of that within a classroom setting and were therefore able to be con- school nyaya.) Nyaya considered rational speculation to sidered as social activity. I noticed that, although there were comprise a fundamental basis for a coherent doctrine of many typologies of more or less spontaneous behaviour pre- knowledge, coming close to what we would now call deduc- sented to satisfy the teacher’s request (i.e., a pattern more or tive logic, relinquished by Buddhist philosophy. less bound to Aristotelian or Megarian-Stoic logic), some stu- The basis of the nyaya school was empiricism: as we shall dents’demonstrative modality could have been thought about see, such logic was consequently quite different from the in a different way from the one expected by the teacher. This Greek Aristotelian model that prevailed throughout the modality brought clearly to mind quite a different kind of Western world at the time. Among other things, Aristotelian logic, highlighting certain factors such as the use of examples logic also shaped, in a form that still persists today, the way or the preliminary enunciation of the thesis. of handling mathematical demonstration. However, while The nyaya approach described in this article shows that this is certainly true at an academic level, it is not so for other cultures have produced intellectual mechanisms of young students at school. [2] ‘truth’ generalization and predication different from Aris- By denying a transcendent principle of the universe (typ- totle’s logic (see, for example, Needham, 1959; D’Amore ical of many Indian doctrines), nyaya built an atomistic and Matteuzzi, 1976; and more recently, Sarma, 2005; physics, within a realistic mould, that supported the exis- Sarukkai, 2005). Both the ideas of collecting evidence of the tence of nine primordial substances and a system of sixteen implicit and unaware use of this logic, along with an analytic objective categories immanent within the real. Its gnosiol- perspective, gave rise to this article. I initially introduce the ogy (philosophy of knowledge) was based on a unity basic elements of this logic, followed by the presentation of between purely sensory knowledge (relative to the external three illustrative cases. I finally present some concluding world) and the conversational one (relative to no matter remarks and reflections. which communicative language). The nyaya doctrine thus I explicitly want to emphasise that my purpose here is acknowledged a form of existence where communicable not to substitute one logical model for another in school edu- concepts are also real entities. cation. From the explorations I have conducted and relate The nyaya school claimed the hegemony of four means of here, it emerges that, in order to reason properly, students gaining knowledge (pramana): have a strong tendency to use particular cases in order to • witness/testimony ‘read’ and ‘see’ the general in them. There is evidence of a • analogy dialectic between generalisation (or abstraction) and con- • perception cretisation (or specialisation) that must necessarily be taken • inference. into account while teaching. Even after this piece of research, I do not believe that I will examine each of these concepts in more detail: these students think in exact accordance with nyaya logic. Witness (sabda) deals with what is reliable from handed- Nevertheless, having recourse to this logic for the analysis of down communication, written or oral. This would include students’ mathematical reasoning highlights the fact that any such things as God’s revelations, handed-down history, didactic analysis presupposes, in one way or another, a prayers and sacred poems. frame of reference: it is possible to use several logical Analogy (upamana, also translated as comparison or frames to account for the students’ deductive behaviour. equivalence) is the way of reasoning that defines an object in Each interpretation of deduction presupposes a logical frame terms of resemblance to others. Note that nyaya analogy of reference, and deviant behaviour is judged only relative to classifies objects according to categories or classes of ana- the particular frame of reference considered. logues, distinguishing between two classes on the basis that they do not have analogous terms. Since an analogy between Some characteristics of the nyaya philosoph- existing objects depends on considerations regarding the ical school object itself (and therefore these are not abstract considera- Although European syllabi seldom take into account the tions but classificatory and experimental ones), this form of study of oriental philosophies, I believe it is fairly well knowledge relates to some present-day concepts also found 26 For the Learning of Mathematics 25, 2 (July, 2005) FLM Publishing Association, Edmonton, Alberta, Canada FLM 25(2) 6/18/05 2:57 PM Page 27 in mathematics. We could refer to geometry, with its closely Application: 4. F(A) from the general related type and proximal genus and specific differences in case, we return to definitions. Or we could mention more developed ones here, the case we are so-called analytic definitions that characterise a class of studying: a force objects through the quotient construction: in other words, by exerts an action means of an equivalence relation. on A Perception (pratyaska) is the relation between the visible Conclusion: 5. P(A) A moves (that which we see with eyes) – or at least with the senses (a relation that is produced by the contact of the sensory organ with the object) – and the image we have of that Classic Buddhist critics argue against the first and the sec- object. I avoid considerations regarding the six senses that ond steps, because they do not belong to true reasoning but nyaya philosophers attributed to human beings, highlighting can nonetheless be included in the thesis. I would like to instead the importance ascribed to the sixth sense, the intel- emphasise that this is frequently carried out in our common lect (manas), because of the regulating and mediating way of reasoning: for example, in didactic action. We point function this ‘organ’ has, with respect to the other five. out the final object of the proof right from the beginning: According to nyaya philosophy, communicable concepts otherwise, it would be impossible to organise that kind of acquire their own reality in contrast with Buddhism that reasoning exactly. I shall return to this issue later on. assigns them the role of a mental image. Buddhists wrongly refused the fifth step, a sort of modus Finally, I consider inference (anumana) that in the nyaya ponens extended to predicate calculus, a logically correct and school represents the sublime stage. The nyaya syllogism (so essential operation for that type of syllogism. The relative called because its form is apparently similar to the Aris- formal linguistic expression is: totelian one) is not widely known. Nyaya distinguished five {(∀X) [(F(X) P(X)) ∧ F(X)] P(X)} {[(F(A) assertive elements in its syllogism (compared with three in P(A)) ∧ F(A)] P(A)} an Aristotelian syllogism): The logical analysis of language, related to the close con- • the statement (pratijna) (not proved; the enuncia- nection assigned to the dichotomous language-object of tion we want to prove) thought, leads to an exact language criticism similar to that • the reason (hetu) of rhetoric in modern times. • the general proposition or enunciation (udaha- According to nyaya, the enemies of correct deduction and rana), followed by an example speaking are: • the application (upanay), also called the second statement • ambiguity (chala), resulting from an improper use • the conclusion (nigamana). of a term (i.e., a wrong use of analogy) • unfinished thinking (jati), looped speech without The following example is a classic nyaya (as well as content Socrates’s pseudo-syllogism for Aristotelian logic): • absurd arguments (nigrahastama), adopted by 1. object A moves (statement); someone without logic: his fate is to be defeated 2. because of a force applied to it (reason); dialectically by someone who operates with logic 3. whenever we apply a force to an object, the object and rational arguments. moves (general proposition); for example: if oxen Nyaya philosophers studied the instances in which their syl- pull a cart, the cart moves (example); logisms led to sophisms. Here are the principal cases of this 4. a force is applied to object A (application); harmful reduction: therefore: 5. object A moves (conclusion). • an incorrect correspondence between the syllo- gism’s constituent parts, therefore there is no It is relatively easy to put this reasoning into symbolic form. relationship between terms Before I proceed to do so, here is a convenient formalism: • an intrinsic absurdity that appears in a term stating Let A, B be given objects, and X a general object; the opposite to that which it should affirm P(X): the open predicate statement, “X moves”; • an explicit absurdity due to the contrast between F(X): “a force is applied to X”. two terms of the syllogism that exclude each other • The open statement F(X) is always true if F(A) is experi- the lack of a proof or a test of one of the terms sup- porting the reasoning mentally verifiable whenever we replace the variable X with • a constant A (we experience its truth through our senses, at the falsity of the major term, the non-existence of least according to nyaya’s empiricist interpretation). the object [3] we are referring to or the attribution Nyaya’s syllogism can be formally interpreted as follows: of false properties to it.