I've never done anything because I wanted to
So I've never done anything because I believed it to be right. Analogous arguments show that we also rarely do things merely because we want to.
We do, of course, do things because they are wantable, or desirable. Our desires aim to capture this fact, but don't thereby become our reason for doing the action.
If it looked odd with beliefs, this is going to look crazier with desires. But it is, again, relatively easy to show. If my reason for doing P was that I desired P, then I should say of hypothetical contexts, where I no longer have the desire, that I no longer have the reason. But this just isn't true of most reasons we take ourselves to have. An obvious example is desiring that I am happy in the future - I have reason to be happy whether I want to or not.
But let's take a harder case. If I imagine myself without the desire to enjoy the delicious taste of tea, it's just not true that I think I have no reason to drink tea in this case. I'd think that I'd have reason to enjoy delicious tea anyway. The deliciousness of tea provides me with reasons to drink it independently of my desires. Reasons aren't dependent on desires in this way.
(Again, in some cases, your reasons for actions do come from your desires. If I desire to play computer games all day, then this is a reason to work away from my computer. This satisfies the condition above: in hypothetical contexts where I lose this desire, I no longer have the reason to work away from my computer. But this kind of reasoning is obviously not the standard kind.)
There's a potential objection I can see coming. The relevant counter-factual is not imagining myself without the desire to enjoy the delicious taste of tea. It's to imagine myself without the desire for tea, period (in which case, without this desire, it seems that I have no reason to drink tea). The word "delicious", you might say, simply means "I desire it", so my counter-factual is really a cheat. If this definition were correct, then even in the counter-factual case, I still desire the tea, because it's been described as delicious.
But this can't be a correct definition. I desire many things without thinking that they're delicious (computer games, again). More generally, there's a temptation to think of all value-labels ("delicious", "fun", "exciting") as desires in disguise. But this just has everything backwards. I desire exciting things because they're exciting; they don't excite me because I desire them. What rationale could I have for my desires if they were always prior to the value that they drive us towards?

On this one I think you're
On this one I think you're way off track. I don't do things because they are wantable. That something is wantable is a belief about that thing, but to do it requires the desire for it. You haven't moved the argument anywhere. I know that tea is tasty but that is not in itself a reason to drink tea. I always know it's tasty but I only drink it when I have a fancy to do so. The fact of its tastiness is a reason to drink it if I fancy a tasty drink.
There's a problem here again with words. As it happens, I do fancy a tasty drink, but I have a bottle of wine open so I'm going to drink that. In one sense of the word 'reason', where it means something close to 'argument', I have a reason to drink tea. I like tea. I fancy a drink. However, if you're using reason to mean my motivation, the 'reason' why I did something, then I have no reason to look for another drink when I've got my wine in front of me.
The titles of your two last posts are trying to subvert language as it is used. They are shocking because they are impossible. You are taking a meaning of the words 'believe' and 'want' and playing on it to arrive at a sentence that doesn't fit the usual understanding of those words. A belief is what seems right to you. A want is something you have reason to do. You cannot deny the community's usage of words. See Wittgenstein again!
I think we probably agree in
I think we probably agree in most of this. There are two complications I neglected to mention in the post, because it was long enough as it was. I think, with these settled, we might find ourselves in agreement.
First, there's a distinction between two senses of "reason". One is normative (or "argument", as you say), the other is motivational. I'm talking here about normative reasons. (As it happens, I'm not sure that there are such things as motivating reasons beyond this, but that's a story for another time.) So the point is that, say, there is something to be said in favour of drinking delicious tea, even if the drink you want happens to be something else. When a normative reason and a want conflict, it's the want that ought to change, not the reason. You say that you only have reason to drink tea when "you fancy it", but isn't all you mean by this "when I'm thirsty and tea will satisfy my thirst"? Being thirsty isn't a want, it's a ground for a normative reason.
The second complication is that "because", in the title, is hugely ambiguous. It might be that wanting tea is a necessary condition of drinking tea, but that it isn't what we drink tea for. Or that wanting tea is a necessary condition of drinking tea being justified, but it isn't the reason why it's justified. Matters here get complex, and I have no real stand on them (at least none so clear in my mind that I can explain it). But take, for instance, the view that to want something just is to be motivated. Then it's kind of true that you drink tea because you want to (you do drink tea because you are motivated to do so), even though there's an important sense in which this is false - you aren't driven to drink tea because you want to (because your motivation can't explain itself). Really, you want to drink tea, and do drink tea, because of whatever generated your motivation to do so.
I'm not certain if this position is correct, but it shows how the possible relationships here can make matters complex with respect to what we mean by "because". I guess I meant by it something like "I've never done anything for the reason that I wanted it", or "I've never done anything on the grounds that I wanted it".
I know this isn't a direct point-by-point response, but I feel that this might clear some disagreement up.
Al
Wants and Desires
"An obvious example is desiring that I am happy in the future - I have reason to be happy whether I want to or not."
I think the want precedes the desire, so I don't understand how you had the reason before any want or personal opinion. And this might be a semantics argument but I don't think desire and want are always related. I desire money but I don't want to work. Or do you argue that if I desire money, and as a consequence work, that I in fact wanted to work because I choose to in order to fulfill a desire?
I'm still a bit confused on you could desire happiness and not want it. Perhaps if you defined the differences between how you view wants and desires. I would say they both highlight a distance between ourselves and an object or idea, based on preexisting reason.
"I desire exciting things because they're exciting; they don't excite me because I desire them. What rationale could I have for my desires if they were always prior to the value that they drive us towards?"
I agree with this but I most people don't apply logic correctly, if at all. You're a student of philosophy and I study psychology, so we both have a unique perspective on human thought and behavior. I desire exciting things because I have chosen to label them exciting based on previous experience. I can also assume to know what makes me happy or what I desire based on external social and cultural factors. A child may desire to be 'cool' so he smokes cigarettes. He views smoking as exciting because he desires the social effect. If the child only did things which truly excited him, then he would not desire unexciting middlemen behavior like smoking. Maybe I'm looking at it the wrong way, who knows, nice article though.
I'm taking "want" to be
I'm taking "want" to be synonymous with "desire" - which in one sense, is a little silly, because people don't usually talk about desire this way. It is, on the other hand, orthodoxy in philosophy to use them this way.
Most people these days tend to say that if you intentionally go to work, then it must be true that you wanted to do so, in some sense. There's an obvious sense in which you didn't want to go, but it also must be true that you saw something in going, otherwise the action was more like an impulse than intentional action. It's in this loose sense that many say that you must have desired to do whatever it was you did, in fact, do.
The point about future happiness was that you ought to, or should, aim to be happy in the future, whether you want to or not. You have a reason (in the sense of "justifying consideration") to be happy in the future that is independent of what you happen to want. People who don't want future happiness are doing something wrong, as it were.
Al