Gender

[Bucky Ball]

To address further the comparison of clinical depression, as a self-reported condition, with gender identity:

Depression cannot be quantified independently of a sufferer's self-reports. There is no chemical test for it -- this is certainly true. In a broad sense, however, there are cases when someone's self-report can be rejected by an experienced professional.

If a new patient met a psychiatrist, and said that he wasn't enjoying ballroom dancing five nights a week quite as much as he used to, and anyway he felt slightly sad after the orgy on Friday, and he claimed that this makes him clinically depressed and in need of strong medication, the doctor would be justified in doubting the self-diagnosis. We all have ups and downs and not all of the downs count as clinical depression, even if it seems that way to the person doing the reporting.

So there are cases in which a patient could say, "Doc, I have clinical depression," and the doctor could justifiably say, "No, you don't."

And this is a key point in scientific claims, I think: falsifiability. If a doctor can point to reasons why a patient's condition does not qualify as clinical depression, then the claim is potentially falsified. It is not as objective or as quantifiable as some other medical issues, but it is something that a professional could rule out, given certain conditions.

For claims about gender identity to reach the same standard of objectivity, there would need to be some standards by which a patient could be shown to be mistaken. The claim could be falsified. This is why a potential objective test -- chemical or whatever -- would also introduce the possibility of showing that the person making the claim is mistaken. "My true identity is female." "No it isn't." Would become a possible objective empirical conclusion.

So if we feel that we should accept unprovable, unfalsifiable claims as true, this is a choice based on our beliefs about how we want our society to work (i.e. ideology) not on science. I am not arguing that it is a bad choice. But I want to be clear that we have beliefs which are not empirical, objective, or scientific. We believe some truth-claims because it is how we think the world ought to be.

Depression is classified (by psychiatrists) all the time. 
Mild, moderate and severe. Probably even further sub-classified after they get to know and have some experience with their patients. 
There will no doubt, be, and as a matter of fact ARE NOW, tests available when they are looking for possible causes of depression. 

Just one example :
"Oxytocin and vasopressin are regulators of anxiety, stress-coping, and sociality. They are released within hypothalamic and limbic areas from dendrites, axons, and perikarya independently of, or coordinated with, secretion from neurohypophysial terminals. Central oxytocin exerts anxiolytic and antidepressive effects, whereas vasopressin tends to show anxiogenic and depressive actions. Evidence from pharmacological and genetic association studies confirms their involvement in individual variation of emotional traits extending to psychopathology. Based on their opposing effects on emotional behaviors, we propose that a balanced activity of both brain neuropeptide systems is important for appropriate emotional behaviors. Shifting the balance between the neuropeptide systems towards oxytocin, by positive social stimuli and/or psychopharmacotherapy, may help to improve emotional behaviors and reinstate mental health."
https://www.cell.com/trends/neuroscience...12)00152-X

The fact that there are NOW many (drug) treatments available, and tests available for the levels of those drugs in the blood, means yes, a patient undergoing treatment has tests available. And in fact, psychopharmacology is a major and entirely separate sub-specialty at most major medical centers.