A new sub-species of fallacy identified by science

Most folks are familiar with the "is-ought" fallacy. For those who aren't, it is the fallacy of saying that because something "is" it therefor "ought" to be. Here's an extreme case to demonstrate why is is a fallacy; pedophilia exists, it "is" a real thing in our world. Following the "is-ought" fallacy we can then conclude that pedophilia "ought" to exist.

Now even though only a handful of demented fucks believe pedophilia "ought" to exist there are a surprising number of people who believe "is" justifies "ought". I hope this over-the-top example clarifies that to adhere to the "is-ought" philosophy is to say that our current world is perfect in every way.

There has been a noticeable decline in the use of "is-ought" lately. But there's a sub-species of it that flourishes. If you simply change the tense of "is-ought" from present to future you get what I call the "can-must" fallacy. This fallacy is hugely popular on the left side of the political spectrum. Folks are very fond of saying that if you are able to do something, usually help the poor, then you are morally obligated to do that something.

To use another extreme example of why this is a fallacy; Germans "can" build gas chambers. It does not logically or morally follow then that they "must" build gas chambers.

A more realistic example; many people will say that if I "can" give a beggar a dollar, I "must" give a beggar a dollar. To demonstrate the disconnect between "can" and "must", I "can" just as easily kick the beggar in the crotch. But it does not therefor morally follow that I "must" kick the beggar in the crotch. Morality cannot be logically linked to ability because we are able to do many things we do not consider moral.

I said above that leftists are quite prone to the "can-must" fallacy. I'd go so far as to say it's their mantra. They are constantly saying that wealthy people "must" help the needy simply because they "can". They typically point out that wealthy people have so much money their lives wouldn't be negatively impacted if even half their wealth was forcibly confiscated for redistribution to the poor. And that may be factually accurate. But it does not logically follow that forcibly confiscating this wealth is morally righteous.

I'll prove this by using exactly the same logic applied to an entirely different situation. First, let's lay out the logic:

1) Group A has exclusive/disproportionate control over some resource that group B would also benefit from.

2) Group A "can" share this resource without noticeably reducing their own ability to use this resource.

Therefor;

3) Group A "must" share this resource with group B.

Those who propose a society based on "altruism by force" would read this as:

1) The wealthy have exclusive/disproportionate control over money that the needy would also benefit from.

2) The wealthy "can" share their money without noticeably reducing their own ability to use their money.

Therefor;

3) The wealthy "must" share their money with the needy.

Any disagreements with this? Is that not the logic they use? If that logic is the logic of morality then we have to apply it to everything if we want to create a moral society, do we not? So let's apply it to something else:

1) Women have exclusive/disproportionate control over vagina that men would also benefit from.

2) Women "can" share their vagina without noticeably reducing their own ability to use their vagina.

Therefor;

3) Women "must" share their vagina with men.

I, of course, do not advocate the idea that women should be obligated to provide needy men with vagina. But I also do not advocate the idea that wealthy people should be obligated to provide money to needy people. Because I do not submit to the fallacy that the ability to do something creates the obligation to do that thing. If you want to obligate people to do something you need actual moral justification for the obligation. "Well, they can" is as ethereal a reason as any other variation of "because".