No, I disagree that we should be asking "Why do you pay taxes?" because this is an open ended question which leaves a lot of room for speculation and asks for an opinion, not an action. Action is what matters. People might convince themselves it's actually a good idea to pay taxes if it's inevitable anyway. But if you ask them "Would you pay it?" then it's a question about an action - yes I would, or no I wouldn't. I don't see why would a person lie.

Yeah, asking why you do something is as much a question about an action as asking whether you'd do it. You're not asking "Would you pay it?" you're asking: "Would you pay it if condition x were false?" You're taking it out of reality, where condition x is true. I agree, you could ask: "Would you pay it?" but the response from the person to that question would be useless without the necessary conditional you've put in it. However, as soon as you put in the conditional about a state of affairs, the person is not analysing their action as it is, but is instead analsying their action according to a state of affairs that may exist. It's as much a mental trick as it is in a case where people convince themselves it's a good idea if it's inevitable.

That goes back to what I said before, which you ignored, if you were to ask me: "Would you still work if you were a millionaire?" I might say: "No." That's true, but it's not true for any useful purpose, because I'm not a millionaire. If you ask me: "Why do you work?" I might say: "Because I like making money." In fact, the latter case is a more truthful statement than the previous case, because I don't actually know what Millionaire-Me might do whereas I do know what Non-millionaire Me would do (work). In any event, the previous question doesn't tell you whether or not I consider the fact I work voluntary, in fact, it doesn't tell you very much anything at all. I personally do consider the fact I work voluntary, but you'd have to ask the latter question to find that fact out. If you just had the previous question and left it, you might as well assume I believe that I work involuntarily.

In the end, you ARE asking for an opinion, the way you propose is a less honest way to do so considering what the inquiry at hand is. Remember, I said that people might have multiple reasons why they pay taxes. This is a sociological fact. Even one person might have multiple reasons why they pay taxes.

If you asked me your question:

"Would you pay taxes if you weren't forced to?" I'd say: "Yes." That's all you get.

My question:

"Why do you pay taxes?" "Fear of jail if I don't, because they pay for roads, social services, because I believe they are a legitimate exercise of function of government."

I'm not lying, no reason to, I pay taxes for multiple reasons and so do most people, and these preferences themselves may be ordered, maybe on my scale of preferences the fear of jail is in-fact less than the fear of potentially unmaintained roads if I have a nice car, for example.

Actually, an idea: Presumably we can synthesise the inquiry, ask "Why" and then ask "Would you still do it", or do it in reverse order. Then, ask people what their preference scales are, etc, etc. You'll find out more information about the reasons people pay taxes, you'll also find that what I said before is true: people pay taxes for multiple reasons.