Full Idea
If your interest in logic is confined to applications to mathematics or other a priori matters, it is fine for validity to preserve certainty, ..but if you use conditionals when arguing about contingent matters, then great caution will be required.
Gist of Idea
Validity can preserve certainty in mathematics, but conditionals about contingents are another matter
Source
Dorothy Edgington (Conditionals [2001], 17.2.1)
Book Reference
'Blackwell Guide to Philosophical Logic', ed/tr. Goble,Lou [Blackwell 2001], p.402