🚀 go-pugleaf

In article <20271@ucbvax.BERKELEY.EDU> kube@cogsci.berkeley.edu.UUCP (Paul Kube) writes:

>I've been assuming two theories to
>have the same explanatory power if they license all the same
>inferences among observation sentences, but this hasn't played much of
>a role in the discussion yet.  (So if one of two equiexplanatory
>theories has a logically stronger assumption set than the other, it
>means the nonobservation sentences it entails are a superset of the
>other; they entail the same observation sentences.)

Very interesting concept of explanation.  But would the "nonobservation
sentences" (by which I assume you mean statements about unobserved or
unobservable entities) necessary have to be the same between two theories of
unequal explanatory power?  Seems to me that different explanations often make
different assertions about non-observed entities.  For instance, Jung talks
about Archetypes and Freud about Ego, Id, and Superego.  One could imagine
these theories explain the same observable phenomena but allege the existence
of *different* non obwervables;  one is not merely a superset of the other.

In this case, you might have a problem deciding which has greater explanatory
power, a problem which wouldn't exist if one was a superset of the other.
You'd have to make some type of judgment about the number of non-observed
entities alleged and the modesty of asserting the existence of these
non-observed entities.  For instance it is *slightly* more modest to say that
the "Id" causes various psychological effects than to say that Men From Mars
cause them.

>My Webster's prefers Ockham, giving Occam as a variant.

OK, but "Occam" is simpler :-).

>But some people
>(maybe Ockham himself) wanted to say that one should always pick the
>simpler theory *because it's more likely to be true*, and I have
>been wondering what reasons there are for believing *that*.

Well, when a theory is fundamentally flawed (such as the Ptolemaic system), it
tends to get very complex when one tries to shoehorn it into existing
observations.  The history of science, as Kuhn points out, is that of gradually
expanding complexity of a given paradigm, followed by a new paradigm that is
simpler and fits the same facts (or most of them).  In this case, simplicity is
a sign of truth.

Whether that's because the universe actually *is* simple or whether we just
get along better with simpler theories is something we probably will never
know.  It's probably safer to believe the latter.  More modest, anyway.
-- 
"Absolute knowledge means never having to change your mind."

Sarge Gerbode
Institute for Research in Metapsychology
950 Guinda St.
Palo Alto, CA 94301
UUCP:  pyramid!thirdi!sarge