Now, this obviously assumes that you know "the other one" is not some Hitler wanna-be or someone else terrible (which could be the case with the candidates we're often forced to choose between (the terrible part, not necessarily the Hitler part) in this country. But, if this is the only information one has (and that unfortunately is the case with the vast majority of voters in this country) one can not argue the logic...
What a sad commentary on our democracy and voting public.