Argument from incredulity


Argument from incredulity, also known as argument from personal incredulity or appeal to common sense, is a fallacy in informal logic. It asserts that a proposition must be false because it contradicts one's personal expectations or beliefs, or is difficult to imagine.
Arguments from incredulity can take the form:
  1. I cannot imagine how F could be true; therefore F must be false.
  2. I cannot imagine how F could be false; therefore F must be true.
Arguments from incredulity can sometimes arise from inappropriate emotional involvement, the conflation of fantasy and reality, a lack of understanding, or an instinctive 'gut' reaction, especially where time is scarce. This form of reasoning is fallacious because one's inability to imagine how a statement can be true or false gives no information about whether the statement is true or false in reality.