[papertyger]

I teach logic, and mistaking evidence for a premise as a conclusion of that premise is a serious logical error.

So what is mistaking a gratuitous assertion for "evidence."

[adiaireton8]

'Evidence' in its broader sense includes reasons, regardless of the persuasiveness of those reasons. If you think the assertion is false, then simply state that it "begs the question". I suspect that's what you were trying to say when you said "non sequitur".

-A8