Did I identify an uncoined fallacy?

The argument is confusing because premise 2 is unclear.

What is meant by "some amounts of X represent all amounts of X"?

In a box set of kitchen plates I have 32 plates. So all amounts of X would = 32. If I take some of these (16 plates), do 16 plates represent all 32?

Or does this mean, when the units are uniform (all the plates are the same), the properties of one can be used to describe the others?

Premise 2 is there simply to address exceptions. When the fallacy is made this premise is assumed to be true, not really considered.

In order to begin with the fallacy you need some amount that is good or bad. If you state that 32 plates are "bad" in some way, and you ignore premise 2, then you might conclude that having 1 or 2 plates is also bad, and that would be a fallacy (if premise 2 is false).

It's much more useful to think of real example when one amount is bad, but another is not, like for example drinking 1 kg of water a day vs. 100 kg of water a day.

Fallacies are not dependent on premise being true or not

Consider this argument:

1. Sample S of population P has quality Q
2. Sample S is not representative of population P
3. ∴ Population P has quality Q

If you say "some rich people are greedy, therefore all rich people are greedy" you are ignoring premise 2, which in this case is possibly true, this is a hasty generalization fallacy. If on the other hand you say "I tested a spaghetti strand and it's done, therefore the spaghetti pot is done", in this case premise 2 is false, and it's a generalization, but it's not a fallacy.

The fallacy occurs because most people ignore the unstated premise. Hidden premises do exist.

I think it should be clear what "some" and all "mean": some ∃(x), all: ∀(x).

The argument of the beard is related, but not the same. In the argument of the beard it's precision the problem; at what point does bath water become dangerous: 60°C? 59°C? 59.9°C? In my amount fallacy this precision doesn't matter; it's fine to say 40°C is good and 70°C is bad; the point is acknowledging there's a distinction, regardless of at precisely which point it happens. Moreover, the argument of the beard is about distinguishing two extremes, my argument is not confined to two extremes, and when two extremes are considered, the point is not to distinguish them, the point is to separate their desirability.

I see what you are saying. If we consider a fallacy in argument form, then make one or more of the premises false, it appears that we no longer have the fallacy. My issue with that is fallacies are about errors in reasoning, not errors of fact. If someone believes that Sample S is representative of population P when it is really not (specific instance), they are factually incorrect. When someone ignores sample size in making a determination about population P, they are reasoning fallaciously. When we are dealing with an informal fallacy, logical form is more of a guide than a rule since informal fallacies are more about context than form. With this in mind, regardless on the truth of premise 2 (let's say Sample S is representative of population P), if someone makes that claim and just happens to right while ignoring sample size, they have still committed the fallacy (i.e., have a problem with their reasoning). So to clarify, "Informal Fallacies are not dependent on premise being true or not."

One more example (anonymous authority )

P1. Person 1 heard some guy 2 say that X was true.
P2. Some guy 2 is anonymous.
C. Therefore, X is true.

It doesn't matter if P2 is true or not. Guy 2 could be the world's premier expert on the issue, but as long as person 1 thinks guy 2 is anonymous, then person 1 is still committing the fallacy.

I don't think you every defined your amount fallacy - you just provided the logical form. How are you defining it? (feel free to link to your blog post, just don't repost it here).

Right, it's an error in reasoning if you ignore premise 2. If you want the error in reasoning in the form itself, then just remove the second premise.

• Some amounts of X are bad
• ∴ All amounts of X are bad

I define just like that: "some amounts of X are bad, therefore any amount of X is bad". If X is income inequality, that's actually a popular argument in the wild: some inequality are good, therefore any amount of income inequality is good.

The amount fallacy.

I list many more examples in my post, but basically anything with a sweet spot can be easily be prey of this fallacy. Another example is immigration: some immigration is good, therefore any amount of immigration is good.

Inferring that something is true of the whole from the fact that it is true of some part of the whole.

It's not the fallacy of composition because there's no whole, and no part.

Supposing a person weighs 70 kg, the lethal dose of water is around 6.3 kg, but this is not known. That person regularly drinks 1 kg of water, so he assumes drinking 10 kg should be fine. Where's the "whole", and wheres the "part" in this fallacy?

And yeah, I'm familiar with emergence, I don't see how it is related to this amount fallacy.

You created a new answer instead of responding to my comment.

This is the definition of composition:

the nature of something's ingredients or constituents; the way in which a whole or mixture is made up.

A tire is a component of a car, you can apply the fallacy of composition there. 1 kg is not a component of the universe of possible mass values which is pretty much all the real numbers (ℝ).

A continuum is not composed of a set of infinitesimal values.

QED