non-trivial extrapolations

One measure of the value of a theory is how non-trivial it is as an extrapolation from more trusted theories.

See Susskind's Topics in String Theory, 8 and 9.

The main example is String Theory as an extrapolation of the Standard Model.

[One could put a metric on theory-space... 

Reverse-engineer the standard model to find the class of Calabi-Yau's that give rise to the particle spectrum...]

Susskind holds that it is not currently possible to find the probability that String Theory is right.

[I disagree, but if it's true String Theory is a trivial extrapolation.]