Compositional Semantics Grounded in Commonsense Metaphysics

If the main business of semantics is to explain how linguistic constructs relate to the world, then semantic analysis of natural language text is, indirectly, an attempt at uncovering the semiotic ontology of commonsense knowledge, and particularly the background knowledge that seems to be implicit in all that we say in our everyday discourse. While this intimate relationship between language and the world is generally accepted, semantics (in all its paradigms) has traditionally proceeded in one direction: by first stipulating an assumed set of ontological commitments followed by some machinery that is supposed to, somehow, model meanings in terms of that stipulated structure of reality.

With the gross mismatch between the trivial ontological commitments of our semantic formalisms and the reality of the world these formalisms purport to represent, it is not surprising therefore that challenges in the semantics of natural language are rampant. However, as correctly observed in [7], semantics could become nearly trivial if it was grounded in an ontological structure that is, “isomorphic to the way we talk about the world”. The obvious question however is ‘how does one arrive at this ontological structure that implicitly underlies all that we say in everyday discourse?’ One plausible answer is the (seemingly circular) suggestion that the semantic analysis of natural language should itself be used to uncover this structure. In this regard we strongly agree with [4] who states: What this suggests, and correctly so, in our opinion, is that in our effort to understand the complex and intimate relationship between ordinary language and everyday commonsense knowledge, one could, as also suggested in [2], “use language as a tool for uncovering the semiotic ontology of commonsense” since ordinary language is the best known theory we have of everyday knowledge.

To avoid this seeming circularity (in wanting this ontological structure that would trivialize semantics; while at the same time suggesting that semantic analysis should itself be used as a guide to uncovering this ontological structure), we could start performing semantic analysis from the ground up, assuming a minimal (almost a trivial and basic) ontology, building up the ontology as we go guided by the results of the semantic analysis. The advantages of this approach are: (i) the ontology thus constructed as a result of this process would not be invented, as is the case in most approaches to ontology (e.g., [5], [8] and [13]), but would instead be discovered from what is in fact implicitly assumed in our use of language in everyday discourse; (ii) the semantics of several natural language phenomena should as a result become trivial, since the semantic analysis was itself the source of the underlying knowledge structures (in a sense, the semantics would have been done before we even started!)

In this paper we suggest exactly such an approach. In particular, in the rest of the paper we (i) argue that semantics must be grounded in a much richer ontological structure, one that reflects our commonsense view of the world and the way we talk about it in ordinary language; (ii) it will be demonstrated that in a logic ’embedded’ with commonsense metaphysics the semantics of various natural language phenomena could become ’nearly’ trivial; and (iii) we finally suggest some steps towards discovering (as opposed to inventing) the ontological structure that seems to implicitly underlie all that we say in ordinary language.

We begin by making a case for a semantics that is grounded in a strongly typed ontological structure that is isomorphic to our commonsense view of reality. In doing so, our ontological commitments will initially be minimal. In particular, we assume the existence of a subsumption hierarchy of a number of general categories such as animal, substance, entity, artifact, event, etc., and where the fact that an object of type human is also an entity, for example, is expressed as human entity . We shall use x ( :: ) animal to state that x is an object of type animal, and Articulate x ( :: ) human to state that the property Articulate is true of some object x, an object that must be of type human (since ‘articulate’ is a property that is ordinarily said of humans). We write x P x ( :: )( ( )) ∃ t when the property P is true of some object x of type t;

. Note now that a variable might, in a single scope, be associated with more than one type. For example, x in (1) is considered to be an entity and an object of type t, where t is presumably the type of objects that the property P applies to (or makes sense of). In these situations a type unification must occur. In particular, type unification occurs when some variable x is associated with more than one type in a single scope. A type unification ( )

As an initial example, consider the steps involved in the interpretation of ‘sheba is hungry’, where it will be assumed that ( ) animal entity and that Hungry is

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