After reading this rant by Fodor, as a layperson, I was idly wondering whether it would be possible to artifically select for flight in pigs. Of course by that time the porcine lineage will probably comprise an entirely new species, but what would be the first step in our breeding experiment? And how would it develop thence, hypothetically speaking?
Intro course to evolutionary biology
I doubt you can get much from the below answer. At the end of the day, the only thing that would really allow you to increase your knowledge is probably an intro course to evolutionary biology such as Understanding Evolution by UC Berkeley for example.
Is it possible to artificially select for flight in pigs?
If by 'artificially select' you refer to selection on available genetic variance, then No, it is not! You'll need plenty of new mutations and it would take a very long time.
You cannot select for something that does not exist. Selection requires pre-existing phenotypic and genetic variation for the trait of interest. No pigs are flying today, so you cannot increase the frequency of individuals flying by selection.
You will need to wait for mutations that confer such flying ability. Of course, there won't be a single mutation that turns a pig into a flying pig. Simply because flight is really not a simple adaptation for a pig! There are few species you could have chosen for which flight would be harder to think of! You are going to go on a long step-by-step procedure, fixing mutations one at a time by selecting every one of them and that will probably take hundreds of thousands of years or maybe millions of years.
I suspect you would consider using their front limb for flying. Here is a potential and extremely simplified step-by-step procedure. Of course, if you were thinking of pigs flying using their ears, the procedure wold be drastically different!
You should probably start by attempting to modify their limbs then. You can maybe try to start by selecting for individuals that are better able to manipulate objects with the front limb. Also start selecting for lighter bodies. Also, remove any selection for the ability of fast displacement or moving in the mud as that would select for their current front limbs. Start with some very very simplistic manipulation and increase up to eventually ending up with individuals that have pretty flexible front limb. Make sure to select for front limb that can move perpendicular to the body axis.
Then I don't know if you should aim to make wings out of skin or out of hair-feather like structure. If you're aiming with feather-like structure, you can try play it out with sexual selection just like it evolved in birds. Let's say you're choosing skin wings. Then, maybe selecting for those having broad and thing front limbs might be a good way to go. In the meantime, you've reached anything like that, you probably managed to reduce the body size of your pigs to the size of a mouse with a very elongated body.
Select for jumping abilities and then slowly for flying abilities. You've got flying organisms who's ancestors were pigs! Be aware nobody is going to fund such a useless and incredibly long experiment.
Evolution really is all about random rolls of the dice, with natural selection deciding the outcome. The question of pigs flying has a precedence. Birds evolved from therapod dinosaurs (one of which is T-rex). But birds have an awful lot of adaptations for flight, including many that must have functioned for some other purpose before they could fly, such as feathers for thermo-regulation. The first wings must have served some function other than flying. Artificial selection is different from natural selection in that it is accelerated through selective breeding. But the principles are the same. You would first breed for small size and light weight. All three tetrapod species that evolved flight did so with their forelimbs. So you would need to look for long forelimbs, and skin in the armpits...Keep in mind these changes would be random. It would require a staggering number of generations. But perhaps, and entirely hypothetically (as you asked), one could try, and it could be done.
I think you have to consider constraints imposed by embryology in this case. Mutations are "random" in the sense that you can't look into the future and plan what would be good for the organism. It doesn't mean that absolutely anything is possible. Wings could only evolve if the process of development allows them to. So you could try with all your might to artificially select pigs that you think might have qualities that allow other flying animals to fly, but wings are never going to appear unless embryological processes are susceptible to this kind of modification.