I previously wrote about the issue of transgender bathroom and locker room usage, but I want to focus in a bit more on the issue of transgender people in general. And my basic thesis will doubtless be rather unpalatable to some people:
Sex is biological, and no amount of surgery or hormone treatment can change your sex.
Now, do not mistake me here – trans people should get surgeries if they want, get hormones if they want, do whatever they want with their bodies. Their bodies, their choices. However, you can no more change your sex than you can change your species (if you are a human – some species CAN switch sexes). You can just become a body-modified individual, akin to getting tattoos, piercings, or breast implants.
What is sex (i.e. biological gender)? Well, first we need to understand sexual reproduction. In species that reproduce sexually, gametes (which carry only a portion of the genetic material that the cells in the species normally carry) fuse together to form a new organism. In certain species, these gametes are not all uniform. In fact, in many sexual species, the gametes come in two types, one of them significantly larger than the other. In humans, for example, the egg is 100000 times the size of the sperm. In species like humans, where the two gametes are distinct in morphology, and in which individual organisms generally produce only one or the other type of gamete, those individuals which are physically capable (barring some physiological malfunction) of producing the large gametes are female, and those that are capable of producing the small gametes are male.
Of course, occasionally, there will be exceptions where a person is hermaphroditic, or is born with malfunctioning gonads (either due to a congenital defect, or because of a physical incident later on, such as being castrated). However, while defenders of social gender theory love to appeal to such exceptions, trans people are usually individuals who start out as biologically functioning members of one sex, but ‘feel’ like the other sex. But the definition of male vs. female is not based on feelings, or on ‘what type of brain you have’ (there is no such thing as a male brain or a female brain – there are trends about which brains are typically associated with males and typically associated with females, but the definition of male and female is independent of the brain). And whereas in some species it is possible for a single organism to transition from one biological sex to the other, in humans, this is not possible. You can modify your body through surgery and through artificial hormone treatments; you cannot go from producing sperm to producing eggs, or vice versa. Ergo, it is not really possible to change your sex. Someone born male can never, biologically, be female (maybe one day it will be possible to make such a change through radical gene modification and surgery, but the technology is not there yet), and neither can a female ever become male. However, whether it is theoretically possible to find a way to make such a transition or not, the fact remains that today, a transwoman is a man who has undergone body modification surgery and hormone treatments, and nothing more. There is no biological reason to consider such a person female, any more than there would be reason to say that a human born biologically male who was castrated is now a female.
Now personally I have no problem with trans people doing whatever they want. In fact, they have the right to modify their bodies, and nobody should be allowed to stop that. However, to claim that by undergoing castration, a penectomy, and hormone treatment, that you are now actually female, is ludicrous.