Comment by fringol__

Also one more thing of note before you go into "but intersex is just error":

"Errors" are important in models. Look up Type 1 and Type 2 errors. If I had a model for hair color, and it couldn't explain red hair, it would be a pretty terrible model. As I mentioned earlier, red hair and obviously, visibly intersex are about on the same order of magnitude.

To further illustrate this concept, consider humans and horses. You'll notice there aren't human-horse hybrids. We can come up with a criteria or a model to separate humans and horses with 1's and 0's and there's nothing in the middle. That's an example of a binary system. We could come up with a bunch of terrible models too that can't differentiate between the two ("mammals"). But ultimately, I could disprove your argument about transgender in sports even ASSUMING a binary model in sex because it's pretty fundamentally irrelevant. If we can't measure the difference between two things (sports performance between ciswomen and transwomen after 2 years of hormonal therapy), then the difference doesn't really matter. The fact that there's transMEN regularly playing in the Olympics is also fairly revealing.

My comment is too long, so I'm going to try to separate it into 2.

> Your comment about "drawing an arbitrary line" doesn't really fit with how biologists see this either, as it's not arbitrary at all but is based on understanding the mechanisms of reproductive function and development…

I talk to biologists all the time for work. I studied biology in college and I work in science and engineering. This is how we talk about data and models in science. What I'm seeing in your response is a fairly deep misunderstanding in how science works, and that's why it might appear to you like I'm not actually answering your question. I am not "proposing a new model" about sex being a spectrum.

Let's take a step back and look at how science works and hopefully we can address this misunderstanding. I'll start with the fundamentals.

We use words to communicate about the world, but they're an imperfect medium. As a quick example, I can call an ant hill a "mountain." What information I might be trying to convey depends on: (1) definition, maybe my definition of mountain is .5 cm, (2) context, maybe I'm speaking metaphorically, (3) relevance, maybe I'm speaking from the perspective of an ant. So key things in communication are (1) definitions, (2) context, (3) relevance. Whatever word I call the object doesn't change the object in any way. This is because all words are representations (or models) of the world, and all models are, by nature, false. They cannot possibly describe every aspect of reality. Words are only as useful as the information they convey. So how can we evaluate the information in words or models?

We evaluate models by treating them as black-box functions and comparing their output to reality. We’re trying to measure how useful or predictive the model is.

How do we do this in practice? We (1) propose a hypothesis, (2) decide which variables are relevant (3) decide on necessary and sufficient conditions or some kind of function. Then we run that function and compare the output of our model to what we measure in reality.

Let’s look at a binary model for human sex. Our hypothesis is that we can define a set of criteria or definitions such that the output is either 1 “female” or 0 “male”. The definition of binary means that it can be fully and completely described by 1 or 0, nothing in the middle. For example, TRUE or FALSE is binary.

Let’s hypothesize that human sex is determined by chromosomes, so therefore XX is female (1) and XY is male (0).

XXY exists (Klinefelter Syndrome). That breaks our model. We can update our criteria. [XX is female] (1) and [XY and XXY are male] (0).

XY + no SRY exists. That also breaks our model. We can update our criteria. [XX and XY + no SRY is female](1) [XY + SRY and XXY is male (0)].

Lots of intersex conditions exist. What does that mean for our model?

To skip forward, we still do not have a defined set of necessary and sufficient criteria where we can describe all outputs of human sexual development with 1 or 0. This means the assumption that the output is binary for our model is broken. Can we still sort everything into binary categories? Sure. Nothing is stopping you from labelling something, but we understand that we’re giving up information while we’re doing this. When we talk about binary models, what we’re referring to is an output of a function or model, not just applying the labels. We do this because we can obviously just apply whatever labels to anything, there’s nothing “scientific” about it. So what’s actually important in evaluating that model is the necessary and sufficient criteria we come up with: the actual function, model etc. This is what I mean by “binary system.” You can still obviously sort the data into binary categories, but the underlying data is fundamentally a spectrum.

This is essentially called a “proof by contradiction.” We had a set of necessary and sufficient conditions, a set of defined definitions (like binary), and we found counterexamples for each one.

Another perspective could be: if I see an individual, what are the chances I could correctly guess characteristics about them (chromosomes etc) based on their phenotype? For male and female, you might be able to fairly accurately guess certain characteristics about them, probably somewhere around 80%. Does that mean that it's impossible for us to sort every individual into two categories? No. But being CAPABLE of sorting or labeling them into two categories does NOT make something binary.

To be honest, the existence of intersex alone should be sufficient to tell you that male and female are not completely “binary” concepts. So we’re dealing with some kind of discrete or continuous “spectrum.” For convenience and simplicity, let’s say it’s male, intersex, female, so discrete but not binary.

Second part:

Now let’s start to address some of your points.

> "The whole point of female and male is to distinguish the two reproductive roles in sexually reproducing species, whether those are hermaphroditic or gonochoric. The sex binary is based on anisogamy, that is, two classes of gamete being of unequal size."

Yes, that's why "female" and "male" are useful abstract concepts specifically to help talk about reproduction in several species. Using these two terms, we can talk about a diverse spectrum of reproductive strategies, including hermaphroditic and gonochoric.

I think your argument breaks down to:

[1] The terms male and female are strictly to distinguish between gamete size in gonochoric species. [Already incorrect, but sure, that’s one possible definition we can use] [2] Humans are a gonochoric species [yes] [3] Therefore ALL humans are either male XOR female

Is this your argument? Because it can pretty quickly be disproven with one contradictory example: intersex humans exist. Deductively arguing from abstracts also means its application is quite limited. For example, it inherently assumes humans are reduced to their reproductive function, which is obviously false. If we’re purely arguing from the perspective of ability to reproduce, then do you have a larger category in mind for “sterile” humans, including infants, the elderly etc? Obviously not all humans are capable of reproduction, which is why it’s useful as an abstract, but that quickly falls apart once you look at concrete examples like individuals. Again, just because you CAN label everything in a binary way, it doesn’t actually mean that the underlying data is binary.

> To take one of your examples: a hirsute woman…

From your response, I don't think I was very clear with these examples. Let me see if I can make my points more clearly.

Every human has male and female aspects. If you look at one individual, how accurately could you predict certain characteristics about them?

If I say "this person has a beard," could you immediately say with 100% confidence that it was a "male"? No. You could probably guess with fairly high accuracy, about 90%, but you could not be 100% confident.

What I was hinting at with these examples is that there is no "necessary and sufficient" definitions of "male" and "female" for individuals where you can predict with 100% accuracy. It doesn't make anyone "more or less" of whatever sex they're categorized as, but these examples illustrate the complexity of the underlying system. The simple fact is that “male” and “female” labels aren’t always very predictive or relevant when being applied to individuals. Not every “male” has a penis or a prostate or is capable of reproduction, and not every “female” has a uterus, ovaries, or is otherwise capable of reproduction. Humans are more than their reproductive capabilities and simple labels such as "male" or "female" can't fully describe those aspects. Reproduction is not always relevant.

> Your comment about "drawing an arbitrary line" doesn't really fit with how biologists see this either…

Yes, when biologists are abstractly talking about reproduction, individual variation isn’t very relevant. They’re not even talking about sterile individuals. Broadly applying those types of generalizations to individuals isn’t helpful.

> Going way back upthread, this was originally about fairness in sport, male physiological advantage, …

You’re making several pretty big logic leaps in here. Let’s try to sort this out.

First, sport isn’t about reproduction. That’s irrelevant, so please stop trying to argue that gamete size has anything to do with sports. So why do we divide sports into "men" and "women" if reproduction isn't relevant? It's because you've correctly seen that sometimes there's physical, measurable differences between the two groups and we as a society want sports to have some aspect of "fairness." There’s a lot to unpack here, though and you’ve made several incorrect assumptions.

“Male physiological advantage” is an incorrect blanket assumption. Where is the “male physiological advantage” in sharp shooting? Olympic Skeet wasn’t separated by gender from 1968 until 1992, when Zhang Shan from China won the gold metal. After that it’s been divided by sex. Some sports are split by gender for different cultural reasons, and yes, in some sports men as a group tend to be much taller and have advantages in certain areas, but this isn’t as universal as you seem to think. Lots of transphobic people tend to focus on trans women in sports, but they’re dead silent on trans men doing fairly well in the Olympics. There are several examples in basketball, wrestling, swimming etc.

> he seemed to think there are medical interventions that can be performed on humans that convert males to female, which is not the case

There is so much variation in human sexual development, as discussed with intersex, that there honestly doesn’t need to be much “medical intervention.” There is a lot of overlap between the sexes, and the fact that it’s actually so hard to define a criteria to separate them, makes this all easy to understand. And that’s where gender comes in. Gender itself is largely a social construct, so we’re pretty flexible on how we define it. Basically it’s pretty easy to see that it’s a real phenomenon and as scientists, we would like to document and discuss this real phenomenon.

> Then you commented stating that sex is a spectrum. This is typically introduced into an argument to try to bolster the claim that it is possible for humans to change sex, …

Sexual development in humans is hopefully by this point fairly obviously a spectrum. Human intersex exists in many different forms. In general, sports have nothing to do with reproduction, so that’s largely irrelevant. However, we as a society would like to make playing sports generally “fair” and there are general, measurable differences between men and women, and yes, sometimes that does mean men have a physiological advantage over women in certain sports. Scientists have already looked into this, and they determined that after 2 years of hormone therapy transwomen are fairly hard to distinguish from the natural variation in ciswomen for all their metric. That’s why there have been rules in place. I’m actually not sure what the rules are for transmen, but the fact that they’re showing up to the Olympics means that they’re probably doing okay.

> So that leads into another issue of why this "sex is a spectrum" idea has been introduced to the world at large. …

Hopefully you have a better understanding of what I mean now. You’re literally using the terms as a spectrum by talking about intersex and using it to describe hermaphrodite species. Being able to apply binary labels to a system doesn’t make it “binary,” what actually matters is the criteria and the output when we’re talking about models. Does that make sense? By calling it a “spectrum,” I’m not actually introducing some new niche model, the fact that I referenced a textbook should make this clear, I’m just saying the data isn’t “binary” and that should be obvious alone from being able to describe so many different species with two terms.

Hope this clears things up!