In a competitive market long term subsides don’t actually benefit the industry’s profit margins. Suppose we subsidize toilet paper, suddenly prices drop and people might start using toilet paper for random other stuff if it’s cheap. However, the industry would simply expand until things stayed about the same.

Where farm subsides play a role is dampening the boom bust cycle.

There's also a very big national security concern. Each country should be able to grow enough food to support it's people. If it can't, it literally faces the threat of starvation in the event of war or natural disaster.

That's just not true. It's about 15% of net incomes currently, but has hovered around 25% of net (in the US):

https://www.agriculture.com/news/business/us-heads-for-highe....

It can be 1% and still be what keeps the majority of farms from going under.

15% is absolutely "I will go bankrupt if I don't have this" territory.

If you drop that in one year sure, but remove all subsidies globally over even 10 years and the market would adjust.

By having firms go bankrupt.

Far from 1:1, like everything there are diminishing returns from fertilizer use etc. So the efficiency per unit of corn etc would be pushed up as the effective price* declines. The price gets pushed up if insufficient food supply gets produced, but demand in a world of obesity is somewhat elastic.

Net result fewer workers, a shift in which farms are profitable, and a ripple effect up the supply chain, but most bankruptcy would be from farms that do so sooner. Aka they would have been bankrupt in a 10 years and now it happens in 5.

*Effective price being the sales price plus total subsidies.

Yes, very impressive high school economics. In the real world you'd be looking at the tax implications of going under and minimizing them.

This of course is too complex to model is completely ignored. A lot like ignoring the atmosphere when designing air planes.

Modeling such interactions is the entire point of economics. We focus far to much on the math but very complex economic system really can be modeled rather accurately. Farm subsidies have been studied extensively and like all long term subsidies end up being harmful to the overall economy.

I wasn't aware economics had solved the halting problem.

Good on them.

Approximation don’t have issues with the halting problem only exact solution do. Your argument no more meaningful than suggesting useful simulation of fluid flows is impossible as you can’t keep track of all the individual atoms.

The difference is that you can bound any macroscopic quantity in fluid dynamics even if you can't solve the equations, however you can't put a bound on iterative processes. Or have economists figured out busy beaver numbers too?

I guess it was only a matter of time before economists stopped misunderstanding physics and started misunderstanding computer science. I mean there's not much prestige left in physics since the end of the cold war. Are we going to see a Turing prize in economics like the Nobel prize?

Modeling the speed of an object in flight is an iterative process.

But, clearly you’re simply using terms without understanding what they mean.

Food is incredibly cheap. If you can get to a farmers market on a not busy day you'd be really impressed what you can get.

Food distribution is a complete disaster. Lots of middlemen between farmers and consumers inflate prices

This is by design, you don't want your farms to underproduce for even a single season. Subsidizing them is worth it. However, we can always talk about whether the current subsidy structure is good for us. I don't think USA's obsession with corn is healthy.