A fallacy is an argument that uses poor reasoning. An argument can be fallacious whether or not its conclusion is true. A fallacy can be either formal or informal. An error that stems from a poor logical form is sometimes called a formal fallacy or simply an invalid argument. An informal fallacy is an error in reasoning that does not originate in improper logical form. For example, The sun has not exploded for all its existence. Therefore, the sun will not explode tomorrow.
Fallacies of presumption fail to prove the conclusion by assuming the conclusion in the proof. Fallacies of weak inference fail to prove the conclusion with insufficient evidence. Fallacies of distraction fail to prove the conclusion with irrelevant evidence, like emotion. Fallacies of ambiguity fail to prove the conclusion due to vagueness in words, phrases, or grammar. Some fallacies are committed intentionally, to manipulate or persuade by deception, others unintentionally due to carelessness or ignorance. There are several types of fallacies based on relevance, ambiguity, and presumption. Some common fallacies include, Red Herring, Slippery Slope, Ad Hominem, Arguing from Ignorance and Circular Reasoning.