Apparently most languages are syntactically based. Some are semantically based. The only way I can describe the latter, since the author, R.M.W. Dixon, gives few examples throughout the book (Ergativity Cambridge U.P.), is by a negative, what it is not. What syntactically based means is that words are given a prototypical meaning and have labels slapped on them like nominative, accusative, preterit, etc. The word then often goes under a derivational process such as making it passive, instrumental, etc. That occurs when the prototypical meaning of the word strays e.g. â€˜He hit me’ implies â€˜with his hand’, otherwise you add â€˜with a stick’. â€˜He hit me’ implies contact was made, the action was completed; if not, another derivation is employed: â€˜He hit at me’ (but didn’t make contact). And so on.
Apparently, semantically based languages do not put restrictions on their words like “takes direct object”, “refers to one completed whole action”, etc.
Comments? Help! Difficult topic.