[Source:] Counterfactuals have this form: If [S:] P were true, Q would be true.
Material conditional: If [P:] P is the case, then Q is the case.
Counterfactuals are not material conditionals! [Does the following para proves this by contradiction?]
[I split the longer sentences here:] [For want of a contradiction, assume that counterfactuals ARE material conditionals.] A material conditional will be true whenever the antecedent is false.A material conditional will be true whenever the antecedent is false. But this can't be the case for counterfactual conditionals since their antecedents are always false, and so every counterfactual conditional would be true. But every counterfactual conditional is not true. Thus counterfactuals are not material conditionals.
Call the first bolded protasis S (for present Subjunctive tense) and the second P (for simple Present tense). Besides the difference in grammatical mood, how do they differ?