# 46. Logical Manipulation ## 46.5. Methodology/Refinements/Sub-species ### 46.5.1. Affirming the consequent This is the fallacy with a general form as follows: Step 1: If X is true, then as a consequence, Y will be true. Step 2: Y is true. Therefore X must be true. These types of argument are a fallacy because they are invalid. Being invalid means that their conclusions do not follow from their premises, i.e., it is possible for their premises to be true and their conclusions false. A valid argument is one in which the conclusion follows from its premises, i.e., it is impossible for its premises to be true and its conclusion false. Take for instance: Step 1: If a god created the universe, we should observe order and design in Nature. Step 2: We do observe order and design in Nature. Step 3: So a god created the universe. In this example, the premise of the argument may be true but the conclusion does not follow from the premises. The invalidity of these arguments has nothing to do with their content and is due entirely to their fallacious logical form. A statement p never follows from the statements if p then q and q. Even if the premises of these types of argument are true, the conclusion doesn't necessarily follow from them. Being a fallacy however, does not mean that the conclusion is false. For instance, the following examples of this phenomenon have true conclusions: Step 1: If President Obama is a Christian, then he is not a Muslim. Step 2: He is not a Muslim. Step 3: So President Obama is a Christian.