Let's begin with an economics joke, motivated by the notion I've sometimes encountered that basic results of the laws of physics and math (population growth, limited resources, conservation of energy and mass) depend on the price at hand.
Questioner: What is 2 + 2?
Economist: Depends on the price.
Questioner: How does the value of 2+2 depend on the price?
Economist: That depends on the price.
I think that only a small fraction of economists deserve this kind of ridicule. But economic greats such as Paul Krugman have routinely complained how certain schools of economists have unlearned numerous things learned during this century. Consequently, we are repeating mistakes made in the early 1930s before the New Deal.
Here's a related joke, this time on the "Deconstructionist" notion (sometimes citing "quantum physics") that reality is based on human belief. It's important to realize that any theory of how reality merely reflects human belief must itself be independent of human belief.
Deconstructionist: Reality is based on human belief.
Questioner: How does human belief affect reality?
Deconstructionist: That depends on human belief.
Questioner: Suppose I disbelieve that reality is based on human belief?
I'm thinking of the cornucopian beliefs that population growth is beneficial because it produces more technology, that the inventiveness of a huge population will more than make up for their huge demand for resources (if the cornucopians even admit such a demand). Of course, the notion that the inventers all need a certain amount of education in order to invent new things these days doesn't seem to occur to the cornucopians.
Of course, a trillion people in abject poverty might produce a few more inventers than a couple billion moderately educated persons living comfortably. That ignores that the trillion impovershed persons occupy a few dozen times as much space, and consume a few dozen times more resources, and are overall far worse off than the couple billion.
Sometime in the eighties, some economist wrote in an opinion piece that we need not worry about running out of fuel. He said something like this.: "Perhaps in the future, we'll simply pick up sand and pull energy out of that." Of course, he was utterly oblivious to basic chemistry and nuclear physics.
In chemical reactions, sand is already oxidized; there's not much further we can go. As for a nuclear processes, there's a reason we're trying for deuterium-tritium fusion rather than ordinary proton-proton fusion, let alone sillicon-anything fusion. Relative terms of difficulty: deuterium-tritium fusion might be like walking 20 feet; proton-proton fusion like walking 100 miles; and sillicon-anything fusion like walking a trillion miles.
I think it would be useless trying to explain the physics and chemistry to that economist, because he wouldn't get it. Even if he believed us, he would still think that perhaps someone might discover some kind of completely new miracle reaction involving sand (sillicon oxygen) enabling us to extract energy. He simply doesn't have the picture of sand as a bunch of atoms bound together, or of the atoms as a nucleus with electrons flying around them, or the nucleus as a tiny bundle of protons and neutrons held together.