Posted another link elsewhere that explains the ambiguous terminology a bit:

https://projectnettie.wordpress.com/

Although rare, some individuals have disorders of sex development (also referred to as intersex conditions). Most of these disorders are male or female specific and do not cause ambiguous biological sex. Some individuals have reproductive anatomies with both male and female features; here, biological sex classification is a complex process with input from medical professionals and parents. Not one of these individuals represents an additional sex class.

I think the answer you're looking for is that ambiguous is being used in the sense of "not immediately obvious, requires further investigation", not "impossible to know in principle"

Either way, thanks for the conversation (and pedantry!)

Take your pick of people with relevant credentials, such as PhD Developmental Biology or PhD Developmental Genetics, that signed a statement that is exactly what I'm saying:

https://projectnettie.wordpress.com/

[..] Biological sex does not meet the defining criteria for a spectrum.

Or someone else:

https://www.nas.org/academic-questions/33/2/in-humans-sex-is-binary-and-immutable

the objective truth is that sex in humans is strictly binary and immutable, for fundamental reasons that are common knowledge to all biologists taking the findings of their discipline seriously.

Even in your best case, when you look at one of the few extremists pushing for a nonsensical redefinition of sex, they still directly admit that gamete size is binary, directly contradicting the strange claim above about a third gamete size:

https://sciencebasedmedicine.org/the-science-of-biological-sex/

When it comes to gametes, these are strictly binary – egg or sperm

I mean c'mon, this is just silly. Crack open your textbook and read it.

The analogy to a messy room fails. I recommend you read this (and the rest of the archive, it's great stuff):

https://talkorigins.org/indexcc/CF/CF001.html

Of note is "The Earth is not a closed system"

Realizing that the root cause is just because you want it to be true is fine, commendable even. Just don't try to justify it post hoc with sciency-sounding arguments.

I disagree with everything you've said, but upvoted because you answered the question.

Even if I've failed to convince you, thanks for actually trying to understand, unlike most in this thread. The best link I can provide for further reading is probably this peer-reviewed article published by a biologist, Why There Are Exactly Two Sexes. Here's a few quotes:

Across anisogamous species, the existence of two—and only two—sexes has been a settled matter in modern biology

Here I synthesize evolutionary and developmental evidence to demonstrate that sex is binary (i.e., there are only two sexes) in all anisogamous species and that males and females are defined universally by the type of gamete they have the biological function to produce—not by karyotypes, secondary sexual characteristics, or other correlates.

This commentary advances a simple claim with broad consequences: In anisogamous organisms, the sexes—male and female—are functional classes defined by the type of gamete an individual has the biological function to produce (Bogardus, 2025). Males have the biological function to produce sperm; females have the biological function to produce ova (Parker et al., 1972). That definition is universal across all anisogamous taxa

As I've said elsewhere in the thread, nothing I've said here is actually a claim that I myself am making. I'm simply stating what the consensus is. Trying to find flaws in that definition is how science works, and it's healthy to poke at it.

https://www.dw.com/en/north-korea-defector-returns-home-calling-south-capitalist-hell/a-39745918

South Korean police on Wednesday said they were investigating the possible abduction of a defector who became a cable television celebrity in her new home, only to end up back in the North.

In the video, Lim - who described herself as "human trash" [..]

Why are you using a human trafficking victim as a meme?

You appear to be using the term "capitalism" in a confusing way. From etymonline:

The meaning "political/economic system which encourages capitalists" is recorded from 1872 and originally was used disparagingly by socialists.

Words can change meaning and all that, but when people complain about capitalism, they don't mean what you're talking about. You seem to mean something like "well-regulated free market", and other people mean "broken, exploitative system that worships greed"

Genuine question, what happens in an anarchist utopia when your neighbors decide that they like your land? If you fight back en masse, doesn't that involve creating a military with a hierarchy that's ripe for seizing power? How can you maintain the social organization for building fighter jets or aircraft carriers or spycraft without those being taken over and used against the people? If you just don't, what happens when your neighbors are a global superpower that has all that?

It seems even more impractical and idealistic than Communism, which at least has an answer to that.

Right, "equivalent to" in the sense that legs are "equivalent to" fins in that they provide locomotion.

Not quite - mating types aren't sex (though the post confuses them). Their gametes are the same size (isogamy), so it's called mating types. Humans have gametes of different sizes, so we have sexes.

It can be true that something is both an important right and used unethically by people that don't actually care about the topic. See Rainbow capitalism as a very related example. Nutomic is right that identity politics are used to create division among the working class, because anything that can create division will be used to do so.