So, context, I'm a libertarian. But, bear with me a moment.

Why are subsidies bad? They "distort the market". How do subsidies distort the market? They cause overproduction of the subsidized good. Where an efficient allocation would tend to fairly precisely match demand to production (more precisely than any other known way of doing it), thus allowing the rest of the capital to go do other useful things, a subsidized good overinvests capital into producing the subsidized good, thus producing an opportunity cost to civilization due to the misallocation of resources into overproducing a good rather than doing something else more useful.

What is the result of farming subsidies? An excess of food. What is food? Food is one of the fundamental foundations of civilization. No food means total chaos in a matter of days. What does precisely producing 100% of the expected target food production means? It means the slightest bobble in production translates to shortages, and as we all know, shortages happen, and in particular, black swans will happen. A free market does not blindly assume everything will be swell and does build in some buffer against expected disaster, but the buffer can always be exceeded and the free market makes it very difficult for a given producer to make their own buffer larger, lest a competitor eat their market share.

Suddenly, a bit of "overproduction of food" doesn't sound like such a bad idea. Ideally we'd be storing the excess as much as possible, though regrettably food doesn't store as well as you'd like. Still, I'm actually in favor of a certain amount of food subsidy.

The ethanol subsidy is still stupid, and given subsidies may be bad on the grounds of being excessive, or because the interest group has captured the regulator and are managing to harvest the surplus directly instead of via overproduction (which is the result we're actually trying to produce for once), but in general, I'm not actually against a bit of overproduction of the foundations of civilization.

Oh, I'm libertarian in many ways as well, but generally agree with you on farm subsidies with the exception of ethanol. I think it's criminal for us to be taking some of the most productive farmland in the world, and growing corn on it to burn in our cars. It's a net negative in terms of energy, and is almost solely due to Iowa having an inordinate amount of influence due to the timing of their primary.

Also, witness the affects of the sugar tariffs that have given rise to the widespread use of HFCS. If it weren't for these, we'd still have Coca-Cola flavored with real sugar. Instead we have to import it from Mexico...

An economics professor of mine said that, besides food subsidies, another reason rich countries have few famines is livestock farming.

There's a lot of energy lost in the process of feeding corn to cattle and turning them into burgers; you could feed more people by eating the corn directly.

So when there's going to be a corn shortage like this year, livestock go to slaughter ahead of schedule, which reduces the demand for corn, and increases the supply of meat.

On its face, eating meat is a luxury, but it actually serves an important function as a buffer against shortages.

If vegetarianism ever became a very popular lifestyle (I'd say, very roughly, if it was adopted by a majority), the risk of food shortages would increase.