Sometimes one reads things such as : a reasoning is valid iff the form of this reasoning is a valid form.
References : Klenk, Understanding logic
This leads to thinking that the fact each reasoning has a form, a " unique" form is crucial.
However, in Peter Smith's introduction to logic, I read that one cannot properly talk about " the" form of a reasoning; every reasoning instantiates many forms.
In that case, is the idea of " valid forms of reasoning" useless?
Is the " valid form" approach to validity correct?