The Republicans’ Milwaukee debate was supposed to be more about issues and less about insults than the previous ones, and it was. Sen. Rand Paul, R-Ky. did the cause of substance a favor by raising the central contradiction at the heart of conservative orthodoxy: “Can you be a conservative and be liberal on military spending?”

Photo by: Flickr/Samuel King Jr

Everyone on the stage including Paul wants to shrink government by reducing spending, except when it comes to the military budget, the single largest expenditure Congress votes on every year, which everyone but Paul wants to lavish with much more money.

Paul’s target, Florida Sen. Marco Rubio, “solved” the contradiction by invoking America’s need to be the strongest military power on earth. To which Paul responded with an actual fact, which is that America spends more on that goal than the next 10 countries combined. His audience could easily supply the corollary question—if that doesn’t make us the strongest military power, what would? Twenty times? Thirty?

Facts are hard to insert into these affairs. Here are a few more: We’re already spending more than $100 billion more in inflation-adjusted dollars every year than we did, on average, during the Cold War. Ending the Iraq and Afghanistan Wars produced the most meager and short-lived savings of any postwar period since World War II, and now we’re headed back up, even without the Republicans’ expansive plans for even more spending.

Why spend more and more? Rubio invoked radical jihadists beheading people and China showing signs of ambition in the South China Sea.

If we’re serious about substance, the next debate could add some to this back-and-forth. A detailed examination of what all this extra military spending would pay for is not in the cards. So let’s just ask the candidates to opine about the biggest ticket item of the next decade, the F-35 Joint Strike Fighter. It is the most expensive weapons program ever launched and surely in the running for the most flawed. All the military services will be buying these planes, some (the Navy) less willingly than others.

Why? To combat ISIS, which doesn’t have any planes? To replace the current model, the F/A-18? This objective may have more to do with the contractors’ needs than with the security of the nation. And why do we need some of these planes to be nuclear-capable, when 1) we have just committed to building a new bomber for this purpose, and 2) we are committed by treaty to proceed in the direction of nuclear disarmament? Will this beefed-up capacity to drop nuclear bombs be deterring the Chinese from the South China Sea? If not, what are they for?

We should hear what the Democratic candidates have to say on these questions too.

Democrats and Republicans almost failed to produce a budget this year, mired as they were in a stand-off over military vs. domestic spending.  At the last minute they compromised to add billions to both. Though these were billed as increases in equal measure, in fact the military side got $59 billion more, courtesy of a separate war budget, a slush fund known as the Overseas Contingency Operations account.

At some point, the debates need to discuss the trade-offs of all this largesse for the military. When hard-nosed budget hawks go soft in the face of the military’s wish lists, the consequences are felt in investments we aren’t making in such things as an educated populace and the infrastructure of a modern economy.

Rand Paul doesn’t care about such things, but the rest of us should.