The law of diminishing marginal utility for example can be logically proven using this method. Alas, knowing it won't make you rich, the world is not that simple.
> the more of something you have, the less of it you want. This phenomenon is referred to as diminishing marginal utility by economists.
Okay, but I have a counter-example. Money. The people who have the most sometimes still act like penny-pinchers, and lust after even more, and haggle over the smallest things. Therefore the "law of diminishing marginal utility" is more a rule of thumb than a law.
Um, there's not a whole lot of economic laws that are less controversial than the law of diminishing marginal utility. I'll give you a rough outline.
If you own a good G, that you could use to satisfy either a desire D1, or a competing desire D2, you will logically choose to use G to satisfy the greater one of these two desires - the one with the greater subjective utility to you. Let's assume that is D1.
Now, if instead of 1 you have 2 of G, you can satisfy both D1 and D2. As we have already established that the utility you have derived from consuming the first G to achieve D1 must be greater than the utility derived from consuming the second G to achieve D2, the utility of the additional unit of G is diminished when compared to the previous one.
Your counterexample isn't one. It's a made-up, incoherent mess, that doesn't show in any way what you claim it does. That starts with the incomplete definition of the law itself, which is part of a single sentence that you pasted off a multi-page Wikipedia article on the topic, which isn't exactly the best source in the first place. Why don't you just try to think through the simple explanatory outline I gave you?
Agree with sibling comment that this is more "heuristic" than "law". There are many things that have basically 0 utility up until some threshold, there are things that become more marginally useful the more of them you have (users for your social media app)
