Argument from ignorance
Argument from ignorance (from Latin: argumentum ad ignorantiam), also known as appeal to ignorance (in which ignorance represents 'a lack of contrary evidence'), is a fallacy in informal logic. It asserts that a proposition is true because it has not yet been proven false (or vice versa).
Speaker A: Infectious diseases are caused by microbes.
Speaker B: What a ridiculous idea!
Speaker A: How so?
Speaker B: It's obviously ridiculous.
Speaker B gives no evidence or reasoning, and when pressed, claims that Speaker A's statement is inherently absurd, thus applying the fallacy..
Comment fallacy in argument from ignorance on Reddit to explain this fallacy. ?