Which informal logical fallacy is committed in the following argument - No one has shown that aliens did not create the crop circles. So the crop circles must have been made by the aliens?

A logical fallacy is a mistake in reasoning that reduces the strength and persuasiveness of an argument. 

Key Points

• There are two main types of fallacies: Formal fallacy and informal fallacy. 
• An informal fallacy is an error in the argument's form, content, or context.
• Argument from ignorance is a mistake in informal logic when ignorance stands in for a lack of evidence to prove. 
• It claims that the statement is true because its falsity has not yet been shown.
• In above Questions, no one can prove that aliens did not create crop circles. 

Thus, Appeal to Ignorance informal logical fallacy is committed in the argument - No one has shown that aliens did not create the crop circles. So, the crop circles must have been made by the aliens.

Additional Information

• Begging the question: the premises of an argument assume that conclusion instead of supporting them. 
• Fallacy of accident: It occurs when an argument that appears in a statistical syllogism when an exception to a general rule is disregarded.
• Appeal to authority: It occurs is the mistaken belief that something is true just because an authoritative person said it.