Most of the time, we can assume that people are trying to make their own life as happy as they can.
Nevertheless, people DO things that would make them miserable some of the time. And even people that are smart, or wise, or whatever.
Now, many assume that every people WANT to be happy, more than anything else, and all the things and attitudes that make them miserable are just and plainly stupid mistakes. But that’s too much assumption. We do not know if people have “to be happy” as the main goal. [We only know that, all else remaining the same, they like being happy.]
Let’s put it this way. People are small vats containing brains, and those do all the decision work. When a brain perceives it’s own functioning and it’s small vat’s conditions as ok, and sees it’s own goals as advancing, it generates the feeling “happiness”. So, it would be fair to say that happiness is good. [It would also seem to have a correlation to whatever it is the brains looks for.] But saying happiness is the goal is too much forced induction – because it does not account for the part of the time people are doing “stupid” things.
When I was a kid, I really thought that the “happiness-is-all” hypothesis was a fairly good one and loathed people for not living accordingly. That is to say, I was critical about people not trying to find the “most happiness” option in every situation, in every dilemma they faced.
Now I am not so convinced. There are many situations where the simple happiness-maximizing solution is naive at best and plainly wrong sometimes. I was involved in the organization of several student meetings, and shared lots of conversations about the subjects with the organizing committees. It turns out most of them are, most of the time, trying to find out how to make the attendees happy. Just a small part of them had the guts to even consider ideas with “unhappy-potential”, as for example cold-baths or long walks over a blazing sun. But it turns out that a large part of the most fulfilling meetings were the ones who dared making the goer unhappy, putting him in unfamiliar situations, giving him cold baths and forcing him to clean the bathroom and things like those.
Just recently, I came to realize that this happiness-is-not-all hypothesis contradicts a whole school of thought, the Utilitarianism guys. But some other day I talk about that.
[edit Apr30th, 2008: rephrased second paragraph, swapped “Positivism” for “Utilitarianism” — oops! Nov17th, 2008: sparse rephrasing.]