Some time ago, I came across the All Souls College philosophy fellowship exam. It's interesting reading throughout, but one question in particular brought me up short when I read it.
What, if anything, is bad about pain?
The fact that I couldn't answer this immediately was fairly disturbing. Approaching it from the opposite angle was much simpler. It is in fact trivially easy to say what is good about pain. To do so, all you need to do is look at the people who are born without the ability to feel it: CIPA patients. You wouldn't want your kid saddled with this condition, unless for some reason you'd find it welcome for the child to die (painlessly) before the age of three, and if that fate were escaped, to spend a lifetime massively inconvenienced, disabled, and endangered by undetected and untreated injuries and illnesses great and small.
But... what, if anything, is bad about pain?
I don't enjoy it, to be sure, but I also don't enjoy soda or warm weather or chess or the sound of vacuum cleaners, and it seems that it would be a different thing entirely to claim that these things are bad. Most people don't enjoy pain, but most people also don't enjoy lutefisk or rock climbing or musical theater or having sex with a member of the same sex, and it seems like a different claim to hold that lutefisk and rock climbing and musical theater and gay sex are bad. And it's just not the case that all people don't enjoy pain, so that's an immediate dead end.
So... what, if anything, is bad about pain?
Let's go back to the CIPA patients. I suggested that they indicate what's good about pain by showing us what happens to people without any: failure to detect and respond to injury and illness leads to exacerbation of their effects, up to and including untimely death. What's bad about those things? If we're doubting the badness of pain, we may as well doubt the badness of other stuff we don't like and try to avoid, like death. With death, there are some readier answers: you could call it a tragic loss of a just-plain-inherently-valuable individual, but if you don't like that answer (and many people don't seem to), you can point to the grief of the loved ones (conveniently ignoring that not everybody has loved ones) which is... um... pain. Whoops. Well, you could try making it about the end of the productive contribution to society, on the assumption that the dead person did something useful (and conveniently ignore why we tend not to be huge fans of death even when it happens to unproductive persons). Maybe we've just lost an anesthesiologist, who, um.... relieves pain.
And... what, if anything, is bad about pain?
Your standard-issue utilitarianism is, among other things, "hedonic". That means it includes among its tenets hedonism, which is the idea that pleasure is good and pain is bad, end of story. Lots of pleasure is better than a little and lots of pain is worse than a little and you can give these things units and do arithmetic to them to figure out how good or bad something is and then wag your finger or supply accolades to whoever is responsible for that thing. Since hedonists are just as entitled as anyone to their primitive notions, that's fine, but it's not much help to our question. "It is a primitive notion of my theory" is the adult equivalent of "it just is, that's all, your question is stupid!" (I don't claim that this is never an appropriate answer. Some questions are pretty stupid. But I don't think that one of them is...)
...what, if anything, is bad about pain?
Let me try to explain this better, then. Imagine we take a person who needs surgery but was never told by their doctor what part of their body the surgery will be on. We perform the surgery without any anaesthetic and with the patient blindfolded. In this case, the pain is giving new information ("AAAIE! MY RIGHT LEG!") but we still don't approve.
kpreid could clarify that this information is useless (in that the patient doesn't gain anything from knowing) and that (s)he meant useful information. But this isn't true either. I could state before the surgery that I will give the patient ten cents if they can tell me which of their limbs I operated on, but this still wouldn't make it okay to perform surgery without anaesthetic.
The way I would have put kpreid's point is that the pain must provide sufficiently useful information to offset its painfulness. If putting someone under surgery without anaesthetic earned someone ten cents, I would consider it an atrocity, but if it was necessary so that the patient could help guide the surgeon by telling them what they feel, saving the patient's life, then it might be a necessary measure.
However, this seems like straightforward utilitarianism, in which the benefit of getting information must outweigh the cost of having such terrible pain. This means it can't be used as a definition of why pain is a cost.
I would say that pain is a cost for other reasons, but that when pain conveys information, the information can be a counterbalancing factor. This makes it a mistake to say that the reason pain is a cost is that it doesn't convey information, equivalent to saying that the reason bombing civilians in Afghanistan is bad is that it doesn't kill Osama bin Laden. The reason bombing civilians is bad is because murder is wrong. Killing Osama bin Laden would be a potential counterbalancing factor that might justify bombing the civilians, but lack of Osama-killing is not the definition of the evil of murder.
Consider someone whose only ambition is to collect every Pokemon in the world. Kpreid's scenario suggests a dichotomy: either it is okay to cause this person pain, or the only reason not to cause this person pain is because it might prevent Pokemons from being collected. I don't think this captures the reason we don't break the bones of Pokemon collectors (even though we all feel sorely tempted sometimes.)
I would agree with this statement. This person's ambition does not involve not having pain; they would gladly be tortured for six years if that were the most efficient way of getting one more Pokemon.