There are different views about all those issues @Jaxk mentioned, of course. I’ve seen studies suggesting that money spent on the military generates significantly fewer jobs than money spent anywhere else. That means that if we cut the military, we might lose 2 million jobs, but gain 2.2 million jobs. Maybe more. There would, of course, be dislocations caused by the transition, but this is the “peace dividend” we are talking about.
As far as foreign policy issues are concerned, I think we are seeing the most efficient foreign policy we’ve had in decades, maybe even in a century. We have largely caused our own problems. We’d have been better off in so many situations by doing nothing. Had we never supported the Shah, the hostage crisis would never have happened. Anti-Israeli feeling would have diminished and the terrorism problem would have been much smaller, or even non-existent. We need to back off, not become more belligerent.
It is true that defense research leads to advances useful in consumer industries. However, once again, people do argue, and with evidence to support them, that the same money, invested in civilian research, would have generated even better results.
I think it is part of a typical pattern that Republicans tend to look at what is, and not what could have been. They discount research showing things would be better in other situations. They say look at what research benefits defense gives us; not what could have been. They say look at welfare fraud; not how much people have been helped compared to what their lives would have been like, otherwise.
Republicans often look through metaphorical glasses tinted by their philosophical views. They select facts that support their views and ignore the other facts. Democrats do this, too, of course, but they do less of it. Democrats tend to believe more in people. Republicans would call them naive. But it all comes down to which facts you choose to see as most important.
Why that is the case, I don’t know. Wish I did. But the relationship between philosophy, beliefs, and political arguments seems to me to be a fruitful area for study.