Full Idea
The rules of deduction are rules of entailment, not rules of inference. They tell us what follows from what, not what to believe on the basis of what.
Clarification
'Entailments' are the logical relationships between statements
Gist of Idea
Deduction shows entailments, not what to believe
Source
Michael Williams (Problems of Knowledge [2001], Ch.18)
Book Reference
Williams,Michael: 'Problems of Knowledge' [OUP 2001], p.215