COMMENT ⊗   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	intens[e85,jmc]		Intensionality and circumscription
C00006 ENDMK
C⊗;
intens[e85,jmc]		Intensionality and circumscription

	The use of facts about knowledge and belief is usually
non-monotonic, i.e. the facts available rarely suffice to
reach the usual conclusions by deduction only.  Here are some
non-monotonic steps.

1. A person normally achieves his goals.  Of course, this applies
mainly to minor goals like getting to the other side of the
room.  Perhaps the fact that the goal is minor should be part of
the statement of the rule.

goal(p,g,c) ∧ minor(p,g,c) ∧ ¬ab aspect1(p,g,c) ⊃ achieves(p,g,c)

We need to figure out how to translate the context into situation
calculus form.

Digression: It seems that we can often talk about achieving several goals
in a context (or situation) without specifying in what order and
even without generating a new situation that is the result of the
achievement.  This is appropriate when there is no interaction
between the goal, i.e. the achievement of one is neither a precondition
for others nor an interference with it.  It may also be appropriate if
it is considered obvious that the goals can be achieved, i.e. the
necessary order is specified at a lower level of thought.

Normally we achieve a set of goals.

Digression: We will use  normally  as an adverb.  Linguistically,  normally
is a modal operator.  It can be compiled out of the theory to
give an extensional theory.  However, the compilation involves the whole
theory and hence is non-monotonic.  Maybe we can plan to eliminate all
intensionality by compiling.  Nevertheless, there is no need to eliminate
intensionality immediately.  Many operations of predicate logic and even
of intensional logic can be performed on formulas in which  normally  occurs.

Digression: Perhaps both situations and contexts are a result of compilation
of intensionals.

Digression: We have a map

context x sentence → sentence valid in wider context;

however, almost all sentences are dependent on some context.

Maybe the way it goes is

c1 ≤ c2 ∧ true(p,c1) ⊃ equiv(p,precisify(p,c1,c2),c1) ∧ true(precisify(p,c1,c2),c2).