An abductive inference takes the form:
P2: A proposition like "If Y then X" can explain X;
C: Therefore, probably Y.
This is the Aristotelian form, which is typically amended slightly for use in science:
P1: Data D;
P2: Hypothesis H explains D;
P3: H is the best explanation of D;
C: Therefore, probably H.
This holds trivially if P3 is replaced by "H is the only explanation of D" and discounting other factors to render this probable or characterising what makes H the best explanation is usually what is at issue in science. Abduction is sometimes called "inference to the best explanation" and was favoured by J.S. Mill.