> I don't think Americans really want to live in a world where America doesn't have an overwhelming military advantage over everyone else

There is a lot of defense spending which doesn't actually contribute to that at all. It's just pork that can't be cut because defense spending is a sacred cow, because defense contractors are huge campaign contributors. Otherwise we could cut the fat and leave the meat.

> Historically, defense spending has been the core of our public R&D spending

I don't see how this is an argument for defense spending. There is no requirement that R&D be done under the auspices of the military. And at a given level of R&D spending, classifying it as defense spending leads to more funding for extravagant weapons systems and less funding for fusion power and solar thermal and other actually useful things.

> Defense spending creates jobs in the U.S. that are difficult to outsource.

This is similarly not an argument for defense spending, it's an argument for federal programs that employ Americans. Why not pay people the same money to repair the infrastructure at home instead of blowing up the infrastructure in the middle east?

> Would it be politically advantageous to spend less on defense and more on alternative energy? Not if you're a politician in Maryland or Georgia or Texas or Alabama whose constituents depend on the jobs created by that spending.

But you're not spending less money, you're just spending it on different things. Why should a Senator from Texas prefer allocating a billion dollars to a defense contractor in Texas over allocating the same billion dollars and hiring the same number of people for alternative energy research also in Texas, except that the defense contractor has more money to donate to his campaign than the university?

Obviously a Senator from one state will be unhappy to see money moved from that state to a different one, but that comes out in the wash. Either the Senator from Texas loses a defense contract and gains an experimental fusion reactor site, or the money goes from e.g. Texas to California and the bill passes with the vote of the Senator from California instead of the Senator from Texas.

> The Senator from Georgia votes in favor of more defense spending because Lockheed-Martin CEO reminded him, using donations and lobbying, that he employs thousands of middle class people in his state.

Do you not see how that can distort the policies adopted? The effects of some policies are diffuse and affect people not naturally organized to defend their interests. Allowing campaign contributions to determine policy creates a preference for organized special interests over the general public and for large organizations over smaller ones.

Here's the naked extreme example: Paul wants the government to tax a hundred million people one dollar each and give it all to Paul. Absent campaign contributions, no representatives pay any attention to Paul because that's a ridiculous policy. Enter campaign contributions, Paul pays a couple million dollars to several representatives in exchange for a hundred million dollar return, and the people being fleeced are too busy to concern themselves with such a small amount of money at the individual level, so the representatives benefit from passing Paul's policy. Repeat thousands of times with various degrees of rationalization for the corruption and you get the Federal budget.