"If you go back and look at the history of the world, tyranny and despotism and how it starts, it has a lot to do with control of thought and control of speech. If people don't speak up for what they believe, then other people will change things without them having a voice. Hitler changed things there and nobody protested. Nobody provided any opposition to him," he said at a New Hampshire campaign stop Wednesday.
Carson immediately clarified he was not referring to President Barack Obama, without elaborating to whom his comparison was directed, adding, "I am saying in a situation where people do not express themselves, bad things can happen."
Last week Carson said he would not consider a Muslim candidate running for president, and has since said he would reject any public servant putting Islam over the U.S. Constitution.
In a number of recent Republican presidential polls, Carson currently ranks second in voter preference behind Donald Trump.