- OK. If you're going to argue war is good for the economy, we're going to need some numbers.
Actually I can elaborate on why any numbers changes would be ultimately false via two arguments, further improving your counter-point.
#1: The Parable of the Broken Window fallacy. If Jimmy breaks a window, John has to buy a new window, thus glass manufacturers continue their work. If Jimmy does not break a window, John keeps his window and instead spends his money expanding his business.
No matter how you slice it, destruction of resources, property, and depletion of manpower (especially from skilled labour) is never healthy for the economy on the grand scale. As for the United States post-WW 2, you can chalk that up to the fact that they took near
zero direct damage from the war, meaning that all the factories and other stuff they built to supply the war effort remained undamaged and easy to convert to other tasks. As for the sudden wealth increase...
#2: War eliminates competitors in an unhealthy manner, it doesn't out-compete them. The United States motor vehicle market is a perfect example of this. Back in the 1950's, the German and Japanese car markets were nonexistent in the face of still recovering from the second world war. When both of these countries recovered, the US car market took multiple steady hits until it equalized to the state that it is at now. Unless you literally commit to the complete extermination of your opposition--every man, woman, and child, every building, every piece of civilization--you will never completely eliminate the opposing competition from this area. Destruction of that magnitude is not only unethical, it's ludicrously expensive and draining on the nation attempting to perform it.
As for the argument of technological progress via war, it only improves tech progress for war-related activities. (In the same sense that mass producing vehicle factories for war results in incidental benefits to the economy afterwards should said factories survive and retain use for the common man, so too can the same argument be made to tech progress.) However, the exact same amount of effort could have been thrown at other, not-war-useful technology, such as cancer research.
War only prioritizes resources to itself, it doesn't magically poof them into existence. War also only has one purpose: To annihilate and destroy, thus setting
back the progression of mankind. As is, imagine what the sheer level of money thrown at the Middle East over the past ten years could have done for the United States if they instead poured it onto their own people, or was used to start paying back some government debt.
I'd imagine it'd have done a lot more productive things then "look, we blew up some people in a land where the worst weapons they have are outdated soviet assault rifles, coarse language, and
shoes."