Many people have argued that the public seems to have an overly negative view of society's development. For instance, this survey shows that the British public think that the crime rate has gone up, even though it has gone down. Similarly, Hans Rosling points out that the public has an overly negative view of developing world progress.
If we have such a pessimism bias, what might explain it? One standard explanation is that good news isn't news - only bad news is. A murder or a famine is news; their absense isn't. Hence people listening to the news gets a skewed picture of the world.
No doubt there is something to that. In this post I want, however, to point to another mechanism that gives rise to a pessimism bias, namely the compound effect of many uses of what I call the Argument from Crisis. (Please notify me if you've seen this idea somewhere else.)
The Argument from Crisis says that some social problem - say crime, poverty, inequality, etc - has worsened and that we therefore need to do something about it. This way of arguing is effective primarily because we are loss averse - because we think losing is worse than failing to win. By arguing that inequality was not as bad ten years ago and that we have now "lost" some degree of equality, your argument will be rhetorically stronger. The reason is that in that case more equality will eradicate a loss, whereas if inequality hasn't worsened, more equality will simply be a gain, which we value less. Hence we will be more inclined to act against inequality in the former case.
Even though the distinction between a gain and an eradication of a loss is important from a rhetorical point of view, it does not seem very relevant from a logical point of view. Whatever the level of crime or inequality is, it would seem that the value of reducing it is the same regardless of whether it has gone up or down the past ten years.
Another reason for why the Argument from Crisis is rhetorically effective is of course that we believe that whatever trend there is will continue (rightly or wrongly). Hence if we think that crime or inequality is increasing, we believe that it will continue do so unless we do something about it.
Both of these factors make the Argument from Crisis rhetorically effective. For this reason, many people argue that social problems which they want to alleviate are getting worse, even though in fact they are not.
I'd say the vast majority of people who use this argument are not conscious of doing it, but rather persuade themselves into believing that the problem they want to alleviate is getting worse. Indeed, I think that the subconscious use of this argument is a major reason why radicals often think the world is on a downward slope. The standard view is of course that they want radical change because they believe that the world has got worse, but I think that to some extent, the causality is reversed: they believe that the world has got worse because they want radical change.
Since the Argument from Crisis is so rhetorically effective, it gets used a lot. The effect of this is to create, among the public at large, a pessimism bias - an impression that the world is getting worse rather than better, in face of evidence to the contrary. This in turn helps various backward-looking political movements. Hence I think that we should do more to combat the Argument from Crisis, even though it can sometimes be a rhetorically effective means to persuade people to take action on important social problems.
There is a rational difference between "crimes (or inequality) has gone up and we need to do something" and "crimes (or inequality) has gone down, but we still need to gain more" : diminishing returns/feasibility issues.
If crimes (or inequality) was indeed lower 10 years ago, it means that reaching a lower point in crime/inequality was possible with a reasonable cost. Of course, it might be impossible now (because of a change in technology, in the environment, in whatever external things we don't really control), but the fact that it was lower before is valid evidence (even if not proof) that is possible to get it lower with a reasonable effort.
On the other hand, if crime or inequality is at an absolute low, it's harder to know if it's possible to get it even lower, or how much effort that would require.
Of course, that doesn't change the core of your reasoning, but it does make the "Argument from Crisis" more than just a rhetorical device - at least, when it's used accurately, ie, when the things are actually getting worse.
Good. I actually gave one reason that shows that there is a rational difference between "crimes (or inequality) has gone up and we need to do something" and "crimes (or inequality) has gone down, but we still need to gain more":
"Another reason for why the Argument from Crisis is rhetorically effective is of course that we believe that whatever trend there is will continue (rightly or wrongly). Hence if we think that crime or inequality is increasing, we believe that it will continue do so unless we do something about it."
You point to another important such reason, however.
Still my hunch is that loss aversion is a major reason why the Argument from Crisis is so effective.