Here's an interesting thought from a scientific journal: Science – good science – does not try to corroborate theories. It attempts to destroy them, to falsify the prime theses, as Karl Raimund Popper so eloquently described. Now it turns out that strong chess players behave like good scientists – a conclusion reached by cognitive scientists Michelle Cowley and Ruth Byrne.
The article goes on to say that people who play badly are too optimistic about their opponents. That is, they tend to see only the good outcomes of their moves. While the better players are skeptical about their moves. They're always looking for ways things can go wrong. I think the eloquent Mr. Popper might have something here. Any comment on the Popper thesis?
I think it's a combination of both. You have to be wary of your opponent's threats. No doubt about that. On the other hand you can't defend everything or you end up defending nothing. (That's from some philosopher or military general or sumpin? I can't remember his name?)
So I think you have to keep an eye on your opponents threats, but sieze the initiative every chance you get in a game of chess.