Published online by Cambridge University Press: 14 March 2022
The conditions are examined under which one theory is said to be replaceable by another, while preserving those features of the original theory which made it serviceable for a given purpose. Among such replacements, special attention is given to ones which qualify as so-called reductions of a theory, and some theorems are proved concerning the notion of a reduction.
For their valuable suggestions I am especially indebted to Henry E. Kyburg, Jr., as well as to an anonymous referee whose specific criticism prompted some revisions and numerous additions.