I only have a rudimentary ( or even less than rudimentary) knowledge of generative grammar.
But what strikes me is that the sentence formation rules are coinded using parts of speech. For example ( the most basic one ) :
Sentence --> Noun Phrase + verb Phrase
What is the motivation for this?
Is there behind this a hypothesis as to cognitive processes involved in speaking. I mean is there a hypothesis such as " subject, object, complement are artificial categories invented by linguists; the real syntactic categories mentally present in the mind of every speaker, the real natural syntactic categories are parts of speech: noun phrase, verb, adverb, preposition, etc. "
Does generative grammar reject traditional syntactic categories such as subject, object, circumstantial complement, agent complement, etc. ?
Why does generative grammar use parts of speech to formulate syntactic formation rules?
PS : I am french, maybe the labels I use are not traditional in english grammar.