The Ontology of the Common Sense World

	We shall begin with a pre-logical discussion; formulas come later.

Examples:

	1. A grabs B and prevents him from stepping in front of a car.
A has prevented a certain specific event.  Presumably our ontology should
allow the event that A prevented as an object.  The syntax of the prevention
statement doesn't seem to be problematical.  The simplest might be

prevents(a,e,s)

meaning that action  a  prevents event  e  in situation  s.  The immediate
question is "what is  e?".  We can ask a somewhat simpler question that may
be adequate, namely, "What are the allowed syntactic forms for  e?".

It looks like  death(B)  is an adequate syntactic form here.

prevents(does(A,grab B),death B,s)

seems to do it, provided we understand that  death(B)  in this context
means only a particular event resulting in the death of  B.  To take
an extreme example, the sentence might still be considered true if  A
grabbed  B  so hard that it killed him.  Maybe it would be better then
if we put it

prevents(does(A,grab B),run-over(B),s)

or even

prevents(A1,E1,s)

with

is-action(A1) ∧ actor(A1) = A ∧ action(A1) = Grab ∧ object(A1) = B

and

is-event(E1) ∧ dies(B,E1)

How about a formalization of the death of Little Nell?

dead(Nell,result(wait,s))

alive(Nell,result(Plan1,s))

ignores(Nell,a) ⊃ dead(Nell,result(a,S0))