|"It's OK, I know what I'm doing"|
And yet we see paradoxically self-destructive behavior all around us. A lot of it depends on one's viewpoint, of course. Vegans think eating a steak is self-destructive, paleos think eating 30 bananas a day is self-destructive. But there are things most people can agree on: sugar is bad, being morbidly obese is bad, drinking two bottles of Jack Daniels a day is bad, taunting dangerous animals in front of a camera is bad (OK, that might've been in poor taste). I argued that there are evolutionary reasons for posturing and risk-taking behavior that supersede mere self-preservation (actually I skipped the posturing part, but that's a gimme).
Now let me (start to) make the case for self-preservation or self-diagnosis, that despite certain obvious failings discussed previously, people are generally those best qualified to choose for themselves.
I think we all have an innate need to apply induction to make sense of our world. Just as the ancient Greeks invented gods to explain everything from disease to lightening, we are hard-wired to come up with hypotheses to explain things like why does my back hurt, why do I have this rash, etc. To try and find a cause-and-effect solution. Not everyone has the time nor inclination to spend hundreds of hours reading about diet and health, and until recently most of this information was much less accessible, or non-existent. (Huzzah Internet and evil bloggers!)
Kurt Harris talks about the failings he's seen in self-diagnosis in his recent post and about the N=1 fetish that's pretty common among the paleosphere (and I've certainly used the term myself). As a practicing physician he's seen a lot of people make silly self-diagnoses, and I think it's justifiably common for doctors to be allergic to this. As someone who used to troubleshoot computer networks, I got pretty sick of people who could barely turn on their computer telling me, "Oh, it's a virus".
Ok, so why are people often so bad at self-diagnosing if we are highly evolved to look out for our own interest (as I believe we are)?
In Blink, Malcolm Gladwell talks about the ability of people with lots of specialized experience to make instant decisions or diagnoses. In fact these instant decisions can often be more accurate than over-thinking the problem. I'm not necessarily a big fan of Gladwell and his rather disingenuous pop-sci format but I think the basis thesis is strong. It is well known that high-level chess players will often just "see" moves. A grandmaster walking around playing 50 people at once doesn't hold all those games in their head, they can simply look at a configuration and have an intuitive grasp of the situation and make an excellent move, over and over again.
As we gain access to more (and more accurate) information, it is possible to broaden the scope of our inductive hypotheses. And as we aquire more experience we become better and better at creating hypotheses. More and better info + experience = better judgement. Add in another important factor, self-interest, and one finds people become very, very good at making decisions.
I think we have a need to create a narrative, to instantly hypothesize that is innate and that's probably worked to our advantage for most of our evolutionary history, and still works more often than not. It's bundled up in the set of heuristics we usually call common sense. I believe this auto-theorizing or compulsive inductionizing, has evolved for a reason.
The typical hunter-gatherer would've been quite familiar with his or her environment. They would've had plenty of information and experience and probably would have made a lot of quick intuitive decisions. And those were probably quite good decisions on the whole (or we wouldn't be here to muse on them). For things beyond their control or ability to influence (hence gain meaninful feedback on) such as disease or weather they probably engaged in rituals but for the things they could control, they were able to make quite good self-interested decisions.