Argument from silence

An argument from silence is an informal fallacy that occurs when someone interprets someone's or something's silence as anything other than silence, typically claiming that the silence was in fact communicating agreement or disagreement.

The fallacy is an argument from ignorance and an informal fallacy.

Synonyms

 * argumentum ex silentio
 * silence implies consent

Explanation
Neither of two people involved in an example of this fallacy may extrapolate anything more from the silence of the silent person than it being just that, a choice of remaining silent in that particular situation. The "vocal" person may thus not argue that the silence of the silent person "allowed" for any number of things on which the other person remained silent, but conversely, the silent person may not argue that their act of remaining silent "disallowed" any number of things on which they were being silent (which would essentially amount to the Nuremberg defense).

Keeping in mind that there is no non-choicemaking, including even the choice of whether to remain silent or not, it differs from situations where silence is inferred but not consciously provided by an unaware person (i.e., if someone remains quiet "in reply" to a question they didn't hear).

The same applies, for instance, if you were to ask a person (who only speaks a language you don't understand) a question in a language they in turn don't understand. While the person is not unaware of your presence, and clearly infers that you are trying to communicate with them, their reaction (and thus "reply") cannot be treated as equal to the reply given from a person who actually understood what you were trying to say (and was able to provide an answer that you could understand), rather than — correctly — treating it as the reply of a person who only understood that you were trying to say something.

Exceptions
If there's evidence that someone would have said something (e.g., if they hadn't gotten cut off by the end of the news broadcast), then their attempt to break their silence is clearly something other than pure silence.

Active silence
If some group or person actively chooses to present no response to an ongoing issue (i.e., ordering that they should not criticize something going on) then it may be seen as tacit support of said issue.

For example, Putin's Russia has done little to stop right-wing extremist "Cossacks" from vigilantism and harassment targeted at gays, immigrants, and liberals (who almost always oppose Putin's rule). This lack of punishment allows this violence to flourish.

Pleading the Fifth
The fallacy differs from situations where silence is encouraged or discouraged, such as utilizing one's right to remain silent (although one has to expressly state that they are invoking said right ), or being into silence, just as statements forced out of people at gunpoint aren't assumed to necessarily represent their own views or opinions. This fallacy pertains to anyone, regardless if they are describing their own silence or the silence of someone else, trying to make that silence out to have been, in that situation, something other than silence.