Michael,

You say:

If a minority can prevent a majority from pooling its money, the minority is coercing the majority into forfeiting its extra 10%, and this is wrong.

This is where we are in complete disagreement.

If you have a scheme (e.g. a plantation system) that will produce a profit, but only if some people (e.g. slaves) involuntarily contribute to it then you do not have a right to that project, even if you sincerely believe that the project makes the unwilling better off. I think that people have a right to their own lives and to the fruits of their labor.

If a minority prevents the majority from imposing that scheme on them or on others, they are not coercing the majority, they are protecting individual rights. And, that is not wrong.

Now, given our current state, I agree that national defense and law enforcement may be areas that are so vital for the exercise of other liberties, and the consequenses of inadequate funding are so great, that they may justify involuntary collection. But, this is a rare exception, and I hope that we can be creative enough to finance these services voluntarily soon.

Other projects, worthy as they may seem, just don't rise to the level of such justification.

And, I will even agree that there may be non-defense projects such that they would provide every single person with more value (in his own opinion) than he could get by using the funds himself; and that creative supporters of these projects would not be able to raise funds voluntarily.

However, I think that a rule that forbids involuntary financing of non-defense projects is better (more moral and more efficient) than one that permits it. In the real world, this power will not be limited to cases where efficiency is increased. The power will be abused by politicians and special interests who see opportunities to use other people's money to further their own interest. Then there will be a race to see who can get more loot for themselves. See this great article.

By the way, a tremendous amount of money was raised voluntarily to help the victims of Hurricane Katrina. Even though rationally-self-interested people could have kept their money and have seen almost as much good done. No, people (like me) decided that the right thing to do with their money was to contribute it to a cause that they judged to be more valuable than any other plans that they had for the money (even though they could get away with refraining). If it is your theory that, unless forced, people will not contribute much money to causes that they can be convinced are worthy (and the benefits are not limited to contributors), then your theory is obviously false.

So, I think that the vast majority of worthy projects would get done without involuntary funding. This will often require creativity (educational/promotional campaigns, telethons, sponsorships, matching contributions, contributions uncommitted until the funding goal is reached, etc.)

Again, some "worthy" projects might go undone, but I'm confident that the moral (and economic) consequences of my rule are better those of yours.

Gil