Full Idea
X believes that if A, B, to the extent that he judges that A & B is nearly as likely as A, or (roughly equivalently) to the extent that he judges A & B to be more likely than A & ¬B.
Gist of Idea
X believes 'if A, B' to the extent that A & B is more likely than A & ¬B
Source
Dorothy Edgington (Do Conditionals Have Truth Conditions? [1986], 5)
Book Reference
'A Philosophical Companion to First-Order Logic', ed/tr. Hughes,R.I.G. [Hackett 1993], p.38
A Reaction
This is a formal statement of her theory of conditionals.