Originally a comment by iknklast on How do we know?

I think to make a moral, rational decision, the ‘is’ column would need to include a few things about what difference this makes to other groups; in short, a risk assessment. We know that men are larger than women (on average). We know that men have held most of the power through the ages, and only recently deigned to share with women (and only after women put in a lot of time, money, and pan to get that). We know that there have been abuses by TiMs in women’s spaces. We know that TiMs on women’s sports teams create a huge advantage for one side over the other. We know that little girls are being exposed to male genitals in supposedly woman-only spaces (something that would be called unlawful if the individual was not TiM).

We know that the trans claim a high suicide rate if denied access. We know that this has not been demonstrated. We know that trans claim a higher than normal murder rate. We know that this has been refuted by the data. (Just the facts, Ma’am.) We know that TiMs claim to be the most oppressed minority ever in spite of evidence to the contrary. We know there have been assaults on women by men in women’s prisons. We know there has been predatory behavior in a certain percentage of TiMs.

All of this, I think, is probably important in making a moral decision. What are the costs to women? What are the costs to men? What are the costs to TiMs? (Time to channel Jeremy Bentham here.)

With this information properly filled in, and evaluated, the moral answer is at least slightly obvious. The problem is that trans allies are more than slightly oblivious, and in fact resistant to even hearing this. They would fill in the ‘ought’ side, even with the data listed, with the idea that they must protect trans, and that women are not in fact oppressed (we’ve had a woman vice president!), and that a few women harmed is a small price to pay for saving thousands and millions of trans lives. Then, of course, they would fill in the ‘is’ side with the ‘fact’ that trans are murdered at higher rates, and that failing to affirm gender identity leads almost inevitably to suicide. Facts be damned.