The relativity I usually think of is the relativity of a theoretical train speeding by at some significant percentage of the speed of light and the mechanics of the light beams bouncing around inside that train as observed by both people in the train and outside the train. Today Wendy and I were talking about a very different kind of relativity, that is the tendency for humans to measure their experiences against those of the people that surround them.
It is well established that people are happiest when surrounded by those less fortunate than themselves. The difference doesn't need to be huge, just noticeable. You aren't going to manufacture happiness by hanging around with homeless people when you are middle class, but you are going to feel better when your social circle is filled with lower middle class folks. The same is true across all kinds of income levels. When someone over commits themselves to a expensive house in a fashionable neighborhood and tries to hang out with their neighbours they tend to be unhappy, whereas those that buy a house they can easily afford and lots of frills tend to be much happier as their neighbours are, on average, less well off.
It shouldn't surprise us that people decide on how fortunate they are in such ways. If happiness was based on some absolute level of material wealth we would all be deliriously happy all the time considering how far we have come since the Dark Ages (or nearly any other age). Instead we tend to base our evaluations of ourselves on those people we see on a regular basis and what their lives are like. There is some correlation to absolute wealth and happiness, but it only ranges from destitute to lower middle class. Once you can go to the store and buy decent food and afford a place to live your absolute wealth level means nothing as far as happiness goes.
Of course one of the major people we compare ourselves against is ourselves. Losing a lot of money or gaining a lot of money are absolutely great ways to lose or gain happiness in the short term. We clearly compare ourselves to how we were recently because these effects rapidly fade with time. The only way to make gaining a lot of cash a surefire path to happiness is to constantly gain in fortune throughout your life. A million dollars at age 30 won't cut it, that would require 5 million by 40, 50 million by 50, etc. to maintain that wave of happiness. Of course instead of chasing constant increases in wealth we could try to be happy with who we are and where we are, but it seems that few humans end up making that leap.
I think this ties into philosophies in interesting ways. The iconically American philosophy I talked about earlier is based on the assumption that those with money are more worthy of it. It justifies the pursuit of money and the desire to see those without money suffer because your financial success is directly tied to your personal worthiness and virtues. I also can't help but think about how the Bible treats this issue - those with wealth and power are definitely treated preferentially by God, and the Bible and God's edicts and decisions are clearly motivated by the desire to regulate wealth and channel it to specific people. In both cases relative wealth is very tightly wrapped up in morality, justifying actions that do not help the group but merely enhance one's own position within the group as moral because those with more money are better people.