With “Trans: Race and Gender in an Age of Unsettled Identities,” UCLA sociology professor Rogers Brubaker seeks to disrupt entrenched ideas about racial identity by bringing transgender experiences into conversation with accounts of race and ethnicity.

Brubaker was prompted to write the book by the furor last year surrounding Rachel Dolezal, onetime president of the Spokane, Washington chapter of the NAACP, who had long presented herself as black, but was revealed to have been born white — and largely reviled for claiming to identify as black. Meanwhile, just 10 days earlier, Caitlyn Jenner’s Vanity Fair story revealing her transgender identity met with broad acceptance and support. In many cases she was heralded as heroic and an example for an often-marginalized community.

“I found it a fascinating opportunity to think about these two identities, both of which are massively unsettled, but in different, yet partly parallel ways,” Brubaker said.

He approached the tricky and hyper-politicized terrain from the perspective of an outsider to both categories, yet as a long-time student of the politics of categories.

“My whole previous 25 years of work had prepared me to think about the way categories work, the way people struggle over categories and the way systems of classification change,” he said.

Brubaker’s book tackles the ways in which people move from one clearly defined racial or ethnic category to another, but also the ways they increasingly seek to position themselves between or beyond established categories. His book is not a defense of Dolezal, but an invitation for readers to “think with trans,” and to explore the idea that the transgender experience can help us rethink the nature of race at a moment when all identities are blurring and shifting.

“A key aim of the multiracial movement is to say that the categories that we have — black, white, Latino, Asian and Native American — do not fit some people,” he said. “Activists proposed ‘multiracial’ as a new category, not as a subdivision or amalgamation of existing categories, but as a cross-cutting category, a category for those who don’t fit existing categories.”

This unsettling of established categories creates concerns on political levels as well as interactional ones, he pointed out.

“There was a big debate about whether ‘multiracial’ should be introduced as a census category. Many political figures opposed that because it could weaken the African-American community, both statistically and politically,” he said.

To add even more complexity, Brubaker noted that the term transgender is supported by a legal and medical infrastructure, by a social movement, and by familiar and resonant cultural stories, none of which is true of the term transracial.

There is a socially recognized and legally regulated procedure for changing one’s gender, but not for changing one’s race, he said. And while gender identity is seen as a purely individual matter, knowable only by the individual, racial identity is understood as depending on matters outside the individual — notably on one’s ancestry, and on the ways one is classified by others.

“Identity is always a two-way street. You can present yourself in a certain way but that doesn’t determine how other people will identify you,” Brubaker said. “When it comes to transgender, the pendulum swung toward saying that your choice of how you want to be identified should be decisive, and other people should respect that choice.”

But this pendulum swing, which has been amplified in the last few years by courts and civil rights agencies — has created a powerful backlash, notably in the area of transgender access to bathrooms and locker rooms.

Brubaker said he hopes to inspire readers to take advantage of the present “trans moment” to bring our understandings of race and gender into dialogue in a way that inspires productive re-thinking.

“Ultimately I come down saying that transracial is clearly ‘not a thing’ — as was widely tweeted in last year’s debates — in the same way as transgender, but it’s nonetheless a usefully provocative concept. It helps us ask productive and interesting questions, because after all race is a social classification system. It’s not a biological reality. So anything that unsettles our convictions about its deep reality, I think is useful,” he said.

For an extended Q&A with Brubaker visit the Princeton Press blog.