One of the issues on which trans activists and feminist activists most vehemently clash is that of transgender and transsexual prisoners. According to trans activists, these prisoners must be housed according to self-declared gender identity as soon as possible. In the past, when feminist activists have expressed alarm and outrage that prisoners born with penises would be allowed into spaces containing some of the most vulnerable women in society (2/3 of whom have not committed a crime of violence), they have been told that their alarm is misplaced.

Besides, only .3% of the population is trans, and even if a person occasionally abused the system, they’d be so far removed from one another, very unlikely to even be at the same prison, making any abuses easy to spot and hard to organize a coverup of. The most powerful prison gangs, which can often shield particular members from scrutiny or serving additional time for jail mishaps, need a population of 3-4% of prisoners (total incarcerated men with gang affiliations are around 16% in prisons, less in jails).

Of course, like with so many arguments from the transgender activist side of the debate, this one is based on feelings, not rigor, logic, or mathematics. Where are the skeptics? Well, there is one here, and we will explore the math today together. You see, the transgender prisoner issue is actually a pretty big one. Bigger than you probably thought, even if you already knew it was a problem.

Allow me to clarify for a moment here. All it takes is one raping man to be too many. There are already stories of men who have used self-castration and gender identity as a way to access and then sexually abuse women in the prison system. What I aim to show, however, is that the problem of simply opening prisons to self-identification is a much bigger problem than it seems at first glance.

In order to quantify the likely number of males who would enter women’s prisons, we must examine two distinct groups: people with genuine histories of gender dysphoric thoughts (who we can assess the number of via transgender prevalence rates), and people with no genuine histories of transgender thoughts who desire to be placed with women (either for sexual access to women or due to safety threats in men’s prison). We can call the first population A, the second B.

Let’s first take a look at population A. Given studies that have shown the criminality of MTF individuals remains, on average, the same as males, let’s assume that they are represented proportionally in the prison population.

But wait. Since 75-80% of transgender people are MTF, not FTM, we can assume the prevalence among males is more like .6%. Still doesn’t seem like much … until you factor in something huge: the vast differential between the number of male and female prisoners.

Check out these statistics. What we see is that while there are 1,225,900 male inmates total, there are only 89,000 female inmates–nearly 14 times as many men as women. That same six-tenths of a percent of the male population that seems relatively insignificant represents a total number of 7,355 inmates. Yes, that’s right. Just six-tenths of a percent of male inmates self-identifying as transgender and opting into women’s prisons would represent an increase to the women’s prison population of over eight percent. About three-quarters of these, assuming the prevalences stayed stable versus the rest of the population, would be male-born people who prefer women sexually.

Eight percent! At that rate, overcrowding becomes a bigger problem than ever, making conditions cramped for female-born people for the benefit of male-born people. And that’s, of course, before we consider population B.

Ah, population B. The terrifying thing about you is that we don’t really know how many of you there are. But we can take some interesting guesses.

Here are some things we know because of the Bureau of Justice Statistics. There are nearly twice as many males whose most serious conviction is murder (157,000) and males whose most serious conviction is rape (159,000) in state prison as there are total female prisoners incarcerated for any crime. Once again, much as with the locker room issue, we must ask ourselves: how likely is it that one rapist in a hundred, one murderer in a hundred, would decide to use this strategy to gain access to women?

If one in a hundred of those rapists utilized this strategy, they’d constitute 1,570 people — or nearly two percent of the total number of female prisoners. If one in a hundred murderers did the same, they’d constitute another two percent.

It does not take many men–men already proven to be violent, men already proven to have no respect for the boundaries of other human beings–to lie about gender identity to make prison a living hell for women.

Trans activists need to understand that for this to be an issue for women does not require “transphobia.” This is a legitimate issue. The class of people born female will experience a material detriment. Admitting population A into women’s prisons, even if literally zero of those people had bad intentions, would cause significant overcrowding at the expense of female-born people for the comfort and benefit of male-born people. Admitting population B into women’s prisons is unavoidable if population A is admitted. Due to the vastly larger starting number of male inmates, population B could create an outsize presence in women’s prisons even if only a relative handful of the worst and most violent inmates used gender identity to leave male prison.

Feminists are often treated like we are being the irrational ones in these debates, like we do not understand science or mathematics. Nothing could be further from the truth. If trans activists looked at the actual problem of prevalence, they’d understand exactly the issue women have with gender identity classifying prison inmates instead of sex. Transwomen of my acquaintance (hello there, Aoife!) who do understand these issues and have taken an honest look at them would NEVER subject women prisoners to forced housing with male-born people.