There has been plenty of criticism of the Categorical Imperative, the concept of Immanuel Kant's that people should act in such a way that their actions can be universally applied. Much of this criticism is based on the fact that Kant's theory downplays the roles of human emotions in moral decision making, or that Kant didn't understand the differing viewpoints of people who weren't White European Males, or just that Kant was an Old Fuddy-Duddy.
However, when dealing with certain people, the level of maturity and cognitive development that Kant takes for granted in all adults is sometimes sorely lacking. And this is often very clear when discussing economic issues with people who are otherwise intelligent.
Those bums, why don't they just get jobs?
I used to try to rush to explain this. After all, the explanation is rather simple, especially to educated people. Even leaving out such issues as human compassion and mental illness, the homeless don't get jobs because there are no jobs. And, as anyone would know who has studied some economics, the jobless rate is kept where it is by decisions made about unemployment and inflation and other such things. But anyone who thought it out to its logical end would realize that in a situation where there is a limited amount of employment available, "get a job" does not fit the categorical imperative. It is not a principle that can be rationally applied to everyone. I've explained this to people, and seen them follow it every step of the way, and then when I finally thought I had them, I saw the spark of recognition fall out of their eyes, drop down on the sidewalk and roll into a sewer grate 10 meters away.
Those people didn't put anything aside, so it serves them right to be out on the street now
In general, saving is a good thing. I tend to save a lot, and not just because cranberry juice is my largest indulgence. However, on the whole, can the categorical imperative be applied to the act of saving money? Can we rationally will that everyone saves all of their money not directly spent on necessities? It would seem unlikely, for a reason of complicated economic reasons, that everyone can save all their money. For example, if everyone was saving all their money, the interest rates paid for savings would drop. And, more directly, if people didn't purchase frivolous things, very few of us would be working at all. It doesn't make much sense to be working in a Big Mouth Billy Bass factory and be expecting people to save their money.
Once again, this is something I've explained to a number of people, having them logically follow my argument, only to have them fall aways at the last moment, because they couldn't make the final categorical leap into universal thinking.
These, are of course, just two quick examples. I don't know too much about the ins and outs of economic theory, but I do know that economics as a whole applies to interactions between people. Economics is also, supposedly a positive science. Yet many people, in their day to day understanding of both individual's behavior and economic policy, try to treat it as a moral gage, and then ignore that it involves interactions between large groups of people and thus they end up making ridiculous conclusions. IF they want to make a moral issue of it, as well as trying to understand the rationality of how large groups of people can act, they should simply apply the simple formula that Kant came up with: think about what would happen if everyone did that.