This is a variation on the "ship out or shut up" argument, and it used to stop me in my tracks. But I've come to believe it's a canard.

A flippant (and not very productive) response to it might go as follows: "Unless memebers of the anti-war crowd are willing to be human shields or strap on a bomb vests and hurl themselves into a crowd of civilians, then they should shut up." But to deliver it would be just as flawed and narrow-minded as the "ship out or shut up" crowd.

A more reasoned response: we don't live under a military dictatorship. Unstead civilians run our military, and the chief civilian (i.e., the commander in chief) is an elected official. Thus every voter has a say (whether pro or con) in what our military does.

On a more strategic front: as every general who recently gave testimony to the Senate Arms Committe said, support for our troops at home is crucial for their success abroad. I can't but help that our military succeeds in their mission in Iraq. I realized that many in the anti-war crowd say they "support our troops" (except those who say they support the so-called "Iraqi resistance" or "minutemen"). But supporting the trops without supporting what they are trying to accomplish seems worthless at best and subversive at worst.

...and if you want crime to decrease you should become a cop, and if you want to prevent fires you should become a firefighter, and if you want to end poverty you should work in a soup kitchen and donate all free time and money to educational programs, and if and if...

Sorry, but I find this argument to be very tired. All people "volunteer" for something. When we encounter a burning building we call the fire department to handle it, and the fact that we did not participate in the rescue has nothing to do with our rights to have an opinion on fires. To take your reasoning to an absurd conclusion, should only those who have actually committed the act of laying down a strip of concrete be allowed to use the highway?