Mark Zuckerberg has been forced to defend Peter Thiel, the Donald Trump-backing Facebook director, saying that the controversial figure's position on the company's board adds to a culture of "diversity" at the social network.
The Facebook founder has been under pressure to address Mr Thiel's position since it emerged earlier this week that the billionaire PayPal founder, who invested in the social network in its early days, had donated $1.25m (pounds 1m) to the Republican presidential candidate's campaign.
"We care deeply about diversity," Mr Zuckerberg wrote on Facebook's internal service, which is seen only by employees. "We can't create a culture that says it cares about diversity and then excludes almost half the country because they back a political candidate.
"There are many reasons a person might support Trump that do not involve racism, sexism, xenophobia or accepting sexual assault. It may be because they believe strongly in smaller government, a different tax policy, health care system, religious issues, gun rights or any other issue where he disagrees with Hillary.
"Our community will be stronger for all our differences."
Mr Thiel, who also helped found the big data startup Palantir, is a contrarian voice in Silicon Valley. He is an advocate of smaller government and shares Mr Trump's view that America's ambitions have declined.
He spoke at the Republican National Convention earlier this year and famously lamented that "we wanted flying cars, instead we got [Twitter's] 140 characters."
The news of his donation to Trump's campaign prompted calls for a boycott of PayPal on social media, despite the billionaire no longer having an affiliation with the company.
Mr Thiel is also a partner at the San Francisco start-up incubator Y Combinator. Its chief executive, Sam Altman, defended Mr Trump earlier this week but Project Include, a group that seeks to promote diversity, cut its ties with Y Combinator.
Facebook itself, like much of Silicon Valley, is often seen as having a Left-wing lean. Mr Zuckerberg's number two, Sheryl Sandberg, has publicly backed Hillary Clinton while the Facebook founder himself is a strong advocate of immigration and has criticised Mr Trump.
"As I look around and I travel around the world, I'm starting to see people and nations turning inward," he said earlier this year. "I hear fearful voices calling for building walls and distancing people they label as others. For blocking free expression, for slowing immigration, reducing trade, and in some cases around the world even cutting access to the internet."
The social network is keen to show it does not take a political line, however. It was embroiled in controversy earlier this year when it was accused of suppressing conservative news in the "trending topics" section that shows its users popular news stories. The furore led it to eventually firing its team of human editors and replacing them with computer algorithms.
According to Facebook's latest diversity report, its employees are 67pc men and 33pc women. In the US, employees are 52 pc white, 38pc Asian, 4pc Hispanic and 2pc black. Its eight-member board is 100pc white and 75pc male.