On the other hand, a measure of illusory thinking may be necessary for our wellbeing. In comparisons between "normal" and depressed people, research revealed an interesting tendency towards depressive realism in depressed people - sometimes also referred to as the "sadder-but-wiser" effect.
The comparisons are fascinating - whereas normal people overestimate how well liked and how competent they are, depressed people do not; normal people recall past activities in a positive glow, whereas depressed people tend to remember successes and failures equally; depressed people often accept responsibility for both successes and failures - normal people deny responsibility for failures; depressed poeple are not prone to an illusion of control, but normal people believe they have more control than they do.
In explaining these tendencies, the basis happens to be a negative explanatory style. More specifically, failures are explained by a depressed person as the result of states or events that are (a) stable ("it will never change"), (b) global ("nobody loves me, everybody hates me"), and/or (c) internal ("i am to blame"). The result? A sense of hopelessness, even despair.
So it appears that when things are tough and you're feeling down, it's kinda beneficial to believe that good things are on the way, that someone is looking out for you, that the world is your oyster, and the sky is the limit ...
So does it take more courage to look a sad thing in the eye, and see it for what it is - or see it for what it is, and still determine to be happy in spite of it? You decide.