Earlier we saw the pattern that heroic values die off in safe times, but I think it's more general than this. Dangerous social situations, broadly defined, strengthen the moral part of our brain in two ways: 1) they increase the chance that we'll actually feel an impulse to consult wise men about how to behave, whereas when we're coasting through life bare of any bruises, we feel we're doing well enough not to have to seek their counsel; and 2) they give us real-world practice in acting morally, whether on the basis of the advice we've gotten or through purely personal trial-and-error. That is the way that natural selection or "survival of the fittest" works, of course: try a bunch of things and keep what seems to work better than the alternatives. As with digging into the book smarts of morality, we're not very likely to get practice with our street smarts unless we have good motivation -- and dangerous times are when the big themes of morality are most palpable (trust, betrayal, revenge, jealousy, death / murder, and so on).
So, I am not using the rates of horrible crimes to estimate how moral a society is. For that, I want to know instead how strong and toned is the moral muscle of man's mind. If we see homicide rates plummeting, does that mean that people developed a stronger moral sense? Not necessarily: maybe they've just become wimpier, or maybe people stay at home more often, rather than expose themselves to risk by wandering around the area. Same if we see rape rates falling: maybe men have lower libido levels than earlier, or maybe women don't wander around alone in public at night as often as they used to. Or if rates of swindling fell: maybe people became less trusting of strangers, thereby preventing the possibility of getting bilked out of big bucks in the first place. You might say that the new societies were more desirable to live in, regarding basic safety, but you couldn't say that they were morally stronger than what they used to be.
Thinking of morality as a "use it or lose it" muscle, I remembered what two economists / evolutionary fitness practitioners have pointed out about exercise. * Namely, for almost all of human existence, we didn't go to a gym at regular intervals, do the same routine, and all at fairly constant intensity. Rather, there was a more chaotic schedule -- we'd never know exactly when we'd need to move around, lift objects, throw things, pull ourselves into a tree, etc. Also, the distribution of intensities would not have been like a symmetrical bell curve, where most activities would have been around average intensity, and where below-average and above-average intensities would be equally likely.
Instead, most of our activities would've demanded little intensity (walking over to speak casually to someone), a fair amount would've required more than that (hauling your stuff from one campsite to another), a handful still more (hurling a large rock or heavy spear), and a tiny number would require a huge burst (lifting a fallen tree off of our brother's leg). And as you know from personal experience and observation of others, light jogging alone is not going to give you large leg muscles -- you also have to subject them to high-intensity stress, like sprinting or doing squats with heavy weights.
The development of our moral sense throughout our lifetime is a complex system, where information about the social world comes in, influences our thought processes and behavior, and our behavior will have similar effects on other people's moral sense, and we'll use that to check and see if we did the right thing the first time around, and so on. There are lots of information feedback loops here.
And so, in Taleb's view, the stressors of our moral behavior, as well as our moral-related behaviors themselves, will have a highly skewed distribution of intensities. Most stressors -- or perhaps "challenges"? -- will require little activity from our moral sense (that old lady with a walker dropped her purse, so should I help her pick it up?), some requiring a bit more than that (your best friend invites you to go for a joyride that could endanger your lives and those of others, so should you?), and a tiny number requiring some real flexing of your moral muscle to grapple with the issues (your brother beats up your wife, so how strong should the revenge be?). And remember, I'm talking about actually having to work through these in real life, not merely reasoning through them in a thought experiment.
As with beefing up your biceps, here it is the challenges that are rarer but more extreme that are needed for our moral sense to be in top form. Otherwise all we face are "should I help the old granny" problems that anyone short of a sociopath can easily master, and we'll wind up with a puny moral sense.
Soon I'll provide some more in-depth examples of how this pattern makes sense of the greater moral orientation we saw from the '60s through the '80s compared to its flagging during the past 20 years, but the big ideas should sink in first. The key link between the muscle view of morality and the level of violence in society is that when the latter is shooting up, so are other wild behaviors like promiscuity and general recklessness (e.g., driving without a seatbelt), and it is these more extreme circumstances that make the social world more morally ambiguous and call for a far greater moral strength to get through it all.
To conclude, notice the parallel between a person who never exercises for fear of spraining an ankle or bumping into someone else while jogging and a person who never wades into morally murky waters for fear that they'll do the wrong thing. In a sense, you're making yourself and others safer from injury by never exercising, but that only leads your body to waste away. And though you may be protecting yourself and others from feeling hurt or wronged by insulating yourself from social situations that throw up extreme moral challenges, this only causes your moral muscle to atrophy. Earning vigorous health requires getting banged up now and then, perhaps giving others a bruise or two in the process, just as a necessary cost of figuring out how to behave morally is to occasionally let yourself down or do wrong by someone else. Those are just the risks we have to accept in order to develop our full potential.
* Here is Nassim Taleb on how lack of extreme stress leads to fragility in complex systems, and an EconTalk podcast with him in which he discusses the idea. Here is another EconTalk podcast with Arthur De Vany in which he talks about these ideas too.