I understand that raising is just losing more money, but how does that justify calling the draw that you will lose way more than you will win. I'm not saying its wrong, but what's the logic? That you hit one of 4 outs, 8 on the turn? You are clearly only playing for the straight. This seems to be more of the type of play to make in a multi way pot to at least get some odds to call. And if the turn does not give you more outs, do you fold to his bet?