I have a personality type that has been described as being both idealistic and cynical. When I first read this, I was in a bit of shock at having someone actually understand part of how my brain works. In the past I had considered these two traits to be mutually exclusive, and had been anticipating my brain imploding due to its inner conflict.
For a long time, part of my Facebook profile read: The optimist sees the glass as half full. The pessimist sees the glass as half empty. The realist measures the amount of water. The idealist measures the capacity of the glass. The cynic looks at it and says it's probably poisoned.
Using this as an example, you can see that I do not view pessimism and cynicism as the same thing. Nor are idealism and cynicism actually mutually exclusive. In fact, according to this example, you could have an optimistic cynic that sees the glass as half-full of delightful poison.
Another way I have explained the differences is as follows:
The optimist says, "Things are wonderful!"
The pessimist says, "No, things are awful."
The idealist says, "Things could be wonderful."
The realist says, "But (set criteria) would have to happen first."
The cynic says, "And you wouldn't like it even if it did."
Yes, there's our wonderful little cynic, ruining everything. Perhaps not all cynics have my sarcastic sense of humor, but I think that is more likely that they do. My cynical side says delightful little things like, "Life is hard, and then you die."
Then I laugh, because I only half mean that statement, because life isn't as awful as my cynical side would have you to believe. Occasionally, life is really wonderful, and my idealistic side gloats while the cynic mutters in a dark corner.
I want to change the world for the better, and at the same time I believe it is impossible to do so. For some reason, though, the cynical side never gains too much control. Otherwise I would simply become a hermit and let the world do what it wants so long as it leaves me alone. I can't make myself do that.
At the end of the day, I will smile at a stranger, try to encourage a friend, do some small thing that makes the world around me a better place. I have an intense desire that the world be better off because I was born, and the cynical side of me can't squash it. I'm not even sure it wants to. Truthfully, my idealism and cynicism balance each other out, the one keeps me trying while the other keeps me from being too disappointed when things don't turn out the way I dreamed.
I wouldn't recommend cynicism by itself to anyone. That would send even the best of us spiraling into a vortex of dark thoughts and depression. But paired with a healthy dose of idealism, it's not so bad.