A lot of people made fun this week of the paucity of evidence that Mr. Trump put forward to support his claim. But researchers point out that if Google somehow went rogue and decided to throw an election to a favored candidate, it would only have to alter a small fraction of search results to do so. If the public did spot evidence of such an event, it would look thin and inconclusive, too.

“We really have to have a much more sophisticated sense of how to investigate and identify these claims,” said Frank Pasquale, a professor at the University of Maryland’s law school who has studied the role that algorithms play in society.

In a law review article published in 2010, Mr. Pasquale outlined a way for regulatory agencies like the Federal Trade Commission and the Federal Communications Commission to gain access to search data to monitor and investigate claims of bias. No one has taken up that idea. Facebook, which also shapes global discourse through secret algorithms, recently sketched out a plan to give academic researchers access to its data to investigate bias, among other issues.

Google has no similar program, but Dr. Nayak said the company often shares data with outside researchers. He also argued that Google’s results are less “personalized” than people think, suggesting that search biases, when they come up, will be easy to spot.

“All our work is out there in the open — anyone can evaluate it, including our critics,” he said.

Search biases mirror real-world ones

The kind of blanket, intentional bias Mr. Trump is claiming would necessarily involve many workers at Google. And Google is leaky; on hot-button issues — debates over diversity or whether to work with the military — politically minded employees have provided important information to the media. If there was even a rumor that Google’s search team was skewing search for political ends, we would likely see some evidence of such a conspiracy in the media.

That’s why, in the view of researchers who study the issue of algorithmic bias, the more pressing concern is not about Google’s deliberate bias against one or another major political party, but about the potential for bias against those who do not already hold power in society. These people — women, minorities and others who lack economic, social and political clout — fall into the blind spots of companies run by wealthy men in California.

It’s in these blind spots that we find the most problematic biases with Google, like in the way it once suggested a spelling correction for the search “English major who taught herself calculus” — the correct spelling, Google offered, was “English major who taught himself calculus.”