I know what you're thinking; "generic article about pessimism." Actually, not quite. If you deem it generic, that's fine, but this is more of a psychological analysis.
Have you ever met someone who seemed to try really hard to give you an impression of intelligence? They tend to use complex words without really knowing the meaning, try to correct you over the most minute of matters, and overall, try to elevate their ego in the realm of intellect? We call these people "pseudo intellectuals".
An intellectual looks to learn and applies their knowledge where it's needed. A pseudo intellectual learns to apply their knowledge where it's not necessary and they tend to botch up the facts. The former will read an article in depth, simply, to learn the material; the latter will skim an article, so they can say they know it. These people tend to read a short wikipedia page and claim to be experts on a subject.
But have you ever had a philosophical discussion with one of these people? One that doesn't require facts, but an outlook on a subject?
It's common for these people to be doomsayers, predicting the apocalypse, noting how the world is terrible and how we're bound for disaster. They tend to spout pessimism about every nook and cranny their scope allows them to speak of in an attempt to further an image of intellectualism.
Granted, a pessimistic view is not mutually exclusive with this type of character, you will find more and more that these particular individuals have a tendency to criticize, skepticize and hypothesize the worst possible events of every matter.
Pessimism is the shortcut to intellectualism, folks. Optimism, while a longer road, by contrast of popular view, grants ultimate success. While clinging to the pessimistic ideology, you will have a much softer travel to an intellectual plane, that is for certain. Optimism, by contrast, is a much longer, bumpier road to wisdom.
"The man who is a pessimist before forty-eight knows too much; if he is an optimist after it he knows too little" -- Mark Twain
"In the long run the pessimist may be proved right, but the optimist has a better time on the trip." -- Daniel L. Reardon
While these quotes are fairly accurate to some respects, they are limited to a scope of shotgun judgment; "jumping the gun", if you will. It is perfectly reasonable to say that an optimist is the weaker breed by the mind, but the reality of the matter is quite different.
Pessimism is a shortcut and while a pessimist can most certainly be intelligent, usually obliterating the average optimist, a successful optimist will always trump that pessimist because they take a road less traveled to that success.
On average, an optimist is the annoying pseudo-intellectual, who stares up at the stars and makes what he believes to be a witty remark about how "small we are". This person, the average optimist, will always lose to the average pessimist.
This, my friends, is the flaw with optimism. However, my own analysis dictates that the end result of the two outlooks pits the successful optimist at the peak.