  Just as, in the case of perception, a number of auxiliary causal factors, such as there being adequate lighting, the perceiver’s sense-faculty being in good condition, the perceiver paying attention, etc., so here too. Nyāya isolates four such factors for special attention, namely: spatio-temporal ‘contiguity’ (sannidhi) of the uttered words; the speaker’s intention (tātparya); ‘syntactic expectancy’ (ākāṅkṣā); and ‘semantic fitness’ (yogyatā) (cf. TS 67). The first is self-explanatory: if the words in the utterance are uttered one at a time over a long period of time, or mixed in with the words of a distinct utterance, it will be impossible form a proper auditory perception of the utterance. The second, ‘speaker’s intention’ is appealed to when the sentence contains an ambiguous word—disambiguation proceeds via consideration of the speaker’s intended meaning. The Manual of Reason defines ‘syntactic expectancy’ as ‘the inability of one word to produce, without another word, an awareness of the relation between them’, and it cites, as an example of an utterance which fails to possess such expectancy, the sentence “horse man elephant”. Clearly the idea is at least that the utterance must be grammatically correct. More than that, there is a suggestion that it is in virtue of the syntactical rules that the unarticulated semantic relations between the words are expressed. What makes it the case that someone who understands the utterance “the cat is on the mat” grasps a united proposition, and not just a list of items [the cat, the on-relation, the mat]? The idea here, perhaps, is that (knowledge of) the syntactical rules generates an awareness of the connecting relations between each of these items.