I know that most of you don't really want to vote for Jones because he is a crook and a gambler, but, still, that is better than voting for Smith, who once went to jail for murder. So you should vote for Jones. Those who commit this fallacy are guilty of uncritically applying a general truism to a particular situation that might have factors that mitigate the validity of the general truth. Milk is good for you, so everyone should drink milk. Exercise is good, so the college should require a PE class every semester.
Free speech is a good thing, so rules against hate speech on college campuses are bad.
The fallacy of appeal to ignorance is the assertion that something must be true because it cannot be proven to be false. Has the burden to prove that claim true. If cases were tried according to the appeal to ignorance, the guilty person would have to prove that he or she did not commit a crime, which is, in many cases, a very difficult thing to do. I belive that life exists in outer space because nobody has ever been able to prove that it does not. Nobody has ever been able to prove conclusively that pornography does not lead to sexual violence.