what is fallacy in philosophy

In philosophy, a fallacy is an error in reasoning that makes an argument invalid. There are many different types of fallacies, and researchers disagree on how to precisely define the term. Some researchers define a fallacy as an argument that is deductively invalid or that has very little inductive strength. Others say a fallacy is a mistake in an argument that arises from something other than merely false premises. Still, others define a fallacy as an argument that is not good. Fallacies can be divided into two categories: formal and informal. Formal fallacies are plain violations of syllogistic rules like undistributed middle and illicit process. Informal fallacies are errors in reasoning that are not purely logical, such as ad hominem attacks or appeals to emotion. Understanding fallacies is important in recognizing them in ones own or others' writing.