On Thursday, Ben Carson pitched an idea for which bathroom transgender people should use: "How about we have a transgender bathroom?" the Republican presidential candidate told Fusion's Jorge Ramos. "It's not fair for them to make everybody else uncomfortable."

Unsurprisingly, LGBTQ advocacy groups were not happy with the idea. HRC blasted Carson's proposal in a statement, arguing that it's tantamount to segregation: "Ben Carson can't go a week without invoking reckless and irresponsible stereotypes about the LGBT community, and his suggestion that transgender people be required to use segregated bathrooms echoes an ugly past our country should never revisit."

But more than that, Carson's comments fundamentally misunderstand what it means to be transgender.

Most transgender people identify as men or women, not a third gender

The majority of trans people explicitly identify as male or female — not part of a third gender. They are, for all intents and purposes, men and women. So placing them in a bathroom separate from men and women essentially rejects who they are and how they identify.

As Michael Hughes, a trans man, noted on Twitter, forcing trans people into the same bathroom as someone of the other gender could lead to some awkward situations:

Emily Prince, a trans woman in Alexandria, Virginia, previously struggled with this type of misunderstanding over her gender identity while signing up for a therapy program. "The first line of the form asked for sex with three options: male, female, and transgender," she told me earlier this year. "Right there, we already have an issue. I'm a woman. I'm not some third sex. There are some non-binary people who don't fit into male or female, but you don't describe all trans people in that way."

Some people do identify as a different gender than male or female, but not all trans people do

As Prince alluded, some people — such as gender nonconforming and genderqueer communities — may identify outside the traditional boundaries of male or female. Although these forms of identity and expression are often associated with sexual orientation — think stereotypes of flamboyant gay men or butch lesbians — they're not intertwined.

Gender nonconforming people don't express their gender in a way society expects them to. Some gender nonconforming people might be androgynous, meaning they don't readily exhibit traits that can easily identify them as men or women. Men who exhibit feminine traits and women who express masculine characteristics may also identify as gender nonconforming.

Genderqueer people generally don't identify or express as men or women, sometimes borrowing gender roles and traits outside society's typical expectations and other times taking elements from both masculinity and femininity. Androgynous people can also fall into this category if they identify their gender as neither male nor female.

"Some people just don't think the term 'male' or 'female' fits for them," Mara Keisling, a trans woman and executive director of the National Center for Transgender Equality, previously told me.

But while genderqueer and gender nonconforming people may sometimes identify as trans, many trans people do not identify as genderqueer or gender nonconforming — and they don't want to be forced to use a separate bathroom.