Saudi Arabia’s laws treat women as second-class citizens, and they were only recently granted the power to drive — and only once it had become clear that this freedom would be short-lived, thanks to Silicon Valley’s driverless car technology, in which the Saudi fund has invested. The Saudis have fueled a civil war in Yemen that is reported to have cost at least 16,000 lives; a report from the United Nations Human Rights Council suggests that Saudi Arabia may be guilty of war crimes for its involvement in the civil war of its southern neighbor. And, thanks to the world’s need for its oil, the kingdom has enjoyed a stunning immunity from justice for its role in financing Islamist extremism around the world.

As Saudi Arabia establishes its new role as one of Silicon Valley’s most prominent investors, the risk grows that its investments will purchase silence. Companies that pride themselves on openness and freedom may find themselves unable to speak ill of one of their largest investors.

Fearing that this would be so, I reached out to several of the technology companies that have received significant cash from Saudi Arabia’s Public Investment Fund. I asked Uber, Wag, DoorDash, Katerra, WeWork, Slack and Plenty if there was any aspect of Saudi Arabia’s conduct in Mr. Khashoggi’s apparent murder that the company disavowed. “Or,” I asked, “does the investment from PIF come with an expectation of remaining silent about Saudi conduct?” All of the companies either declined to respond at all, or responded with a refusal to comment on the record about the Saudi kingdom’s behavior.

Silicon Valley has enough issues already: Tech companies are compromising our elections, upholding monopolies, and profiteering from the abuse of privacy. There is no need to add to that list by becoming a reputation-laundering machine for one of the least admirable regimes on earth — a regime that would seem to violate all the values that Silicon Valley is proud of trumpeting.

Arvind Ganesan, director of the business and human rights program of Human Rights Watch, told me in an email that the Riyadh conference “will be a litmus test for businesses’ willingness to go along with a Saudi narrative that is increasingly disconnected from reality.” Foreign businesses “risk more than reputational harm,” he added. “They’re enabling part of his narrative.”

If the Valley is sincere that it will “change the world” and “do the right thing, period,” then the Saudi government’s billions of dollars in investment capital should be returned, and Silicon Valley companies should refuse any further investments. Every business leader and news organization of conscience should pull out from the Public Investment Fund-powered conference and suspend any involvement with Saudi-funded projects like Neom — at the very least, until the disappearance and potential murder of Mr. Khashoggi have been suitably investigated, but perhaps beyond that, given the regime’s broader human rights record. (I became aware during the writing of this piece that The New York Times had been listed among the conference’s sponsors but has since withdrawn.)

Mr. Khashoggi couldn’t be intimidated by his country. He might have given his life for his bravery. Silicon Valley must choose where it stands on the questions of lies and truth, cowardice and courage that defined his work. Turning a blind eye to the human rights abuses of Saudi Arabia is no way of “changing the world.”

Anand Giridharadas is the author of, most recently, “Winners Take All: The Elite Charade of Changing the World.”

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