Universal semantic primes have an inherent grammar—a "conceptual grammar"—which is the same in all languages; that is, each semantic prime has certain combinatorial properties virtue of the particular concept it represents. The formal realisations (marking patterns, word order, constituent structure, etc.) may differ from language to language without these underlying combinatorial properties being disturbed. Although groups of primes share particular properties and can be regarded as falling into natural classes, virtually every prime has some idiosyncratic properties, giving each one a distinctive syntactic signature. The cross-linguistic viability of the current model of NSM grammar has been checked in considerable depth and detail across a range of typologically divergent languages. Key references are Goddard and Wierzbicka (eds., 2002), Goddard (ed., 2008) and Goddard and Wierzbicka (2014). Some of the main aspects of the NSM grammar can be sketched as follows.
Substantives and substantive phrases
The elements which combine directly with substantives include: (a) determiners, e.g., 'this someone', 'the same thing', 'somewhere else', (b) quantifiers, e.g., 'two things', 'many people', 'one part', 'many kinds', (c) evaluators, e.g., 'something good', 'something bad', and (d) descriptors, e.g., 'something small'. They can also be modified by like-phases, e.g., 'people like this', 'someone like me'. There is much more to the grammar of substantive phrases than can be covered here; for example, the relational substantives KIND and PART each can head phrases sui generis, which can be termed "classifier phrases" and "part-hood phrases", respectively, such as 'one thing of this kind' and 'one part of this thing'. Some of the quantifier primes have a "subset" valency options, e.g. 'one of these people/things', 'two of these people/things', 'some of these people/things'.
Predicates, valency options and complements
We can think of a simple NSM clause as consisting of a predicate, such as HAPPEN, DO, SAY or WANT, together with one or more substantive phrases whose nature is constrained by the identity of the predicate. In addition to a minimal frame, predicates typically allow extended frames in which additional arguments identify or fill out the aspects of the situation implied by the nature of the predicate. These optional extras are termed "valency options". For example, HAPPEN allows us to speak not only of 'something happening', but also of 'something happening to someone' or 'something happening to something'. Likewise, with DO it is possible to add an additional argument and speak of 'doing something to someone else' or 'doing something to something'. DO can also be extended by the "instrument" option ('do something with something') and the "comitative" option ('do something with someone').
his means that all the following arrays are licensed by NSM syntax. Furthermore, all predicates can combine with the "meta-predicates" or "predicate operators" NOT and CAN.
- something HAPPENS - [minimal frame]
- something HAPPENS to someone/something - [undergoer frames]
- someone DOES something - [minimal frame]
- someone DOES something to someone else/something - [patient frames]
- someone DOES something with something - [instrument frame]
- someone DOES something with someone - [comitative frame]
In some cases, NSM researchers propose valency options which are seldom recognised in mainstream grammars. For example:
- someone THINKS about someone/something - [topic frame]
- someone THINKS something (good/bad) about someone/something - [topic + complement frame]
- someone THINKS like this: " – – " - [quasi-quotational frame]
- someone SAID something - [minimal frame]
- someone SAID: " – – – " - [direct speech frame]
- someone SAID something to someone - [addressee frame]
- someone SAID something about something/someone else - [locutionary topic frame]
- someone SAID (some) words to someone else - [directed words frame]
- someone SAID something (not) with words - [verbal means frame]
- I SAY: – – – - [performative frame]
Most obviously, there is an inherently bi-clausal construction connected with the semantic prime IF, exemplified in sentences such as: 'If you do this, people can think something bad about you'. The primes KNOW and THINK have the capacity to take propositional complements. For example, 'I know that something bad happened to this someone'. WANT is also complement-taking, but it has special characteristics that set it apart from the other complement-taking predicates.
Several other complex sentence structures are allowable in the natural semantic metalanguage. These include (i) "quasi-relative clauses" headed by PLACE or TIME; for example, 'I am far from the place where I live', (ii) adverbial clauses of time and reason, e.g., 'when something like this happens, ...', 'it happened like this because someone wanted it', (iii) "analogy clauses" with LIKE~AS as a linking element, e.g., 'I want to do something bad to this someone, like this someone did something bad to me'.
All these combinatorial possibilities mean that the phrasing of NSM text can be quite complex.