Grice on "probably" in the Kant lectures ("Aspects of Reason", 2001, section 2.4)

by JLS
for the GC

In "Aspects of Reason" (1977, Stanford -- in 2001, section 2.4), Grice discusses Davidson's arguments in 'How is weakness of the will possible'. The examples include:

If the barometer falls, it will probably rain.
The barometer falls.
Ergo, ceteris paribus it will probably rain.

The underlying form being:

"Prob (h, p)" in the alethic realm becomes

"Good (h; a, b)" in the practical realm.

"More prob (h; p, q)" in the alethic (doxastic) realm

becomes

"Better (h; a, b)" in the practical (boulemaic) realm.

--- Another example from the practical realm:

If, prima facie, Act I would be a lie and Act II would not,
P is better than Q

Act I, but not Act II, would be a lie.

------

Ergo, ceteris paribus, P is better than Q.

--- Grice applies Davidson's "Principle of Total Evidence", from the doxastic realm, to the boulemaic realm. And he doesn't necessarily fail!