This may not make sense to you. I have two glasses in front of me, one tall and narrow, one short and wide. If I were to pour the cranberry juice in one to the other, in front of a preschool child, they would say that there was more in the tall glass and not believe me if I said differently. If you don't follow this, you could be like that child, or perhaps I am just a sloppy writer.
From my scant knowledge of developmental theories, children pass through a few stages between becoming verbal and adolescence, which is considered kind of a stopping point for cognitive development. These stages are preoperational, concrete operational and formal operational. They are the stages when the child does not understand rules, when they understand that rules apply to certain situations, and when they understand that the rules apply as abstract entities on a universal scale. Sometimes these rules are applied to scientific situations, sometimes to moral situations, and to every other type of situation. But in any case, these stages of development seem to unfold fairly consistently if a child is given the opportunity to develop.
If you have noticed a trend in this chain of development, it is that the individual, as they grow older, grows more abstract. At first they don't understand that the juice being poured is the same, despite their sense impressions. After they develop the ability to conserve, they understand that on a practical level, a certain volume is a certain volume, and doesn't change. And when they reach the formal operational stage, they understand that mass and energy are not created or destroyed, merely transformed. This is a simple example of course, in cases such as moral reasoning, it gets much more complicated.
My own experience is that abstract reasoning typically peaks around the ages of 16-20. Which is, why of course, people of that age are the most self assured and self righteous when it comes to their actions and beliefs. From there, most people take a small "hook" in development to one degree or another. Against the previously prevailing trend, individuals begin to reason less abstractly. This takes many forms: most of us, just having to deal with reality, tend to deal with life on a slightly less idealistic basis, worrying about the consequences of our actions, rather than their abstract righteousness. In some people, this continues into a greater questioning of what "the rules" mean, and why they exist.
The reason why this is happening does relate to the prior progression: as we grow older, we begin to abstract more and more. Finding the supreme set of abstractions to deal with the world seems to be a final step, but actually there is a step beyond that: our abstractions themselves become objects to be examined as any other objects would be. The individual becomes metacognizant.
In some fields, this is helpful; in others, not so helpful. For example, as much as I close my eyes and hum the name of the Supreme Ultimate, I can't make the value of pi change (just yet). On the other hand, many other sets of "rules" can be transformed rather easily. For example, I can take the anonymous they, and realize it is not stuck in heaven's firmament, and realize that this group of anonymous judgers is actually a construct under the control of my mind. A field such as economics is especially ripe for this kind of metacognitive manipulation. Money is an object in an atomic fashion, but at the same time money is the field in which individual pieces of money travel through. While we can not change the atomic nature of money, we can choose the conditions under which it travels. There are many ways once we have decided to transform the field instead of the objects within it, we can participate in our own manipulation.
Personally, along with my incessant reading of philosophy, my knowledge of how to transform the field comes from my study of Martial Arts. When attacked, the attacker will always attempt to "set the rules", and if they manage to succesfully do so, the attacked is eventually going to lose. Only by changing the rules, rather than by attempting to fight the attacker directly, can the attacked hope to escape. For example, if someone attempts to start a "bullying" fight with me for the purpose of humiliation, there is nothing outside of my own ethical considerations to stop me from transforming it into a "real fight" where I attempt to seriously injure them. If someone attempts to mug me on the sidewalk, I have the option of "changing the field" by jumping into the street and letting them worry about the attention that braking cars will cause.
My realization that I can change the field in which I operate allows me to be more free as a person.