In reality the “semantic web” is, and can only ever be, a ”syntactic web”. Syntax is merely form — the shape of arbitrary objects called symbols , within a formal notational system adopted by an agreed and shared convention. Computation is the rule-based manipulation of those symbols, with the rules and manipulations (“algorithms”) based purely and mechanically on the shapes of the symbols, not their meaning — even though most of the individual symbols as well as the combinations of symbols are systematically interpretable (by human minds) as having meaning.
Semantics, in contrast, concerns the meanings of the symbols, not their shape, or the syntactic manipulation of their shapes. The “symbol grounding problem” is the problem of how symbols get their meanings, i.e., their semantics, and the problem is not yet solved. It is clear that symbols in the brain are grounded, but we do not yet know how. It is likely that grounding is related to our sensorimotor capacity (how we are able to perceive, recognise and manipulate objects and states), but so far that looks as if it will only connect symbols to their referents, not yet to their meaning. Frege‘s notion of “sense”, which is again just syntactic, because it consists of syntactic rules, still does not capture meaning. Nor does formal model-theoretic semantics, which likewise merely finds another syntactic object or system that follows the same rules as those of the syntactic object or system for which we are seeking the meaning.
So whereas sensorimotor grounding — as in a robot that can pass the Turing Test — does break out of the syntactic circle, it does not really get us to meaning (though it may be as far as cognitive science will ever be able to get us, because meaning may be related to the perhaps insoluble problem of consciousness).
Where does that leave the “semantic web”? As merely an ungrounded syntactic network. Like many useful symbol systems and artificial “neural networks”, the network of labels, links and connectivity of the web can compute useful answers for us, has interesting, systematic correlates (e.g., as in latent “semantic” analysis, and can be given a systematic semantic interpretation (by our minds). But it remains merely a syntactic web, not a semantic one