[FOM] Progress in philosophy

[John McCarthy]

Consider the following events:

     1. Frege's first order logic with predicates of several
     argumnts, rules for manipulating quantifiers, a theory whose
     completeness could later be proved.

     2. Frege's distinction between sense and denotation.

     3. Lewis's calculus of strict implication and the later
     formalization of modal logic.

     4. Goedel's incompletness theorems.

     5. Tarski's results about truth.

     6. Hintikka's treatment of truth.

Were these philosophical events?  Did they constitute progress in
philosophy?  My opinion is yes to both questions.

I admit that if all that interests you is the existence of God, these
are not philosophical events.  Science has had more effect on belief
in God than explicit philosophical reasoning.

I look at philosophy from the standpoint of artificial intelligence,
which shares many problems with branches of philosophy, especially
epistemology, and even ontology.

Johan van Benthem wrote, ``AI is philosophy pursued by other means,''
and I think that's a pretty good slogan.

One of my own interests is the formalization of individual
concepts and propositions.  About this Carnap wrote

``...it seems that hardly anybody proposes to use different variables
for propositions and for truth-values, or different variables for
individuals and individual concepts.''
 - Carnap 1956, p. 113 of Meaning and Necessity

I do in my 1979 article ``First order theories of individual concepts
and propositions'' published in Machine Intelligence 4 and
available as http://www-formal.stanford.edu/jmc/concepts.html.

Stuart Shapiro (the computer scientist) not Stewart Shapiro (the
philosopher) also treats individual concepts as objects.

My view is that ordinary language refers directly to concepts,
i.e. treats them as objects, and it loses expressiveness to avoid 
this in formalizations.

In any case AI needs to treat knowledge and belief in a formal
way.  To ban such treatments as empty logicism is to discard what 
has been always regarded as epistemology.