What does it mean to silence someone? Well, here are a few possible answers. An oppressive regime doesn't like what someone is saying so it kills him. Or it locks her away where her voice can no longer be heard. Elsewhere, a law is passed laying down draconian penalties for publicly articulating some view or other. At a meeting, the audience shouts down a speaker so that he or she cannot be heard. There may well be further tyes of instance, but that's a start.
The philosopher Jason Stanley, however, proposes a more expansive meaning of silencing. It would accommodate putting about untruths about a politician that are designed to discredit him or her. Stanley writes:
Silencing extends to politics when outlandish claims are made about public figures. Suppose that President Obama really was a secret Islamist agent, or born in Kenya. In that case, he would be grossly insincere. We would have no reason to believe what he said in any situation. The function of disseminating such claims about the president is not to object to his specific arguments or agenda. It is to undermine the public's trust in him, so that nothing he says can be taken at face value.
To me this suggestion is grotesque. As president of the United States of America, Barack Obama is in one of the very best positions of anyone in the world today to have his voice heard. I can't see the point of the conflation of meanings: telling lies about someone is not, in general, good for them. It may make it more difficult for them to persuade some others of their views; but it isn't the same as silencing them.
Here's another of Stanley's examples of putative silencing:
Whatever one thinks of the wisdom of the 2003 invasion of Iraq, it is difficult to have a reasoned debate about its costs and benefits when the invasion itself is called "Operation Iraqi Freedom."... It is difficult to have a reasoned debate about the costs and benefits of a policy when one side has seized control of the linguistic means to express all the positive claims.
Yes, people tend to use language in ways helpful to themselves and not to their opponents. But in the case at hand - the Iraq war - nobody 'seized control of the linguistic means to express all the positive claims'. Since when did supporters of the Iraq war monopolize the means of expression? In fact, they didn't; critics of the war had plenty to say and said it.
Stanley says 'In silencing, one removes the ability of a target person or group to communicate', but these two examples of his are not apt. There are, as he warns, 'dangers [in] the manipulation of language', but the above are not compelling instances of it - whatever one might think of the example (of pornography) from which he begins.