An adoptive admission is where a person is assumed to agree with the statement of another if it is said in her/his presence and she/he chooses to remain silent and doesn't deny what is said. The person's silence is considered to be agreement with the statement made by the other. The charge of failing to condemn what other posters have written has been a frequent one here.
In a forum like FFL, however, where there are so many posters and lurkers and where over a hundred a messages a day are posted, it doesn't make practical sense to apply the charge of adoptive admission for anyone's failure to respond to what someone else posts. People could consider responding to what other posters actually write, rather than what they don't write. There would be less argument, but maybe that would be a good thing. ***