Do not assume that because you hold an opinion, the same is true of the rest of the world.
Politicians are especially adept at assuming that their position is that of the majority.
Deductive reasoning is a way of thinking that draws inferences from general statements or uses generalizations to apply what is true in one instance to what is true in another related instance. You must be careful not to assume that what applies to one situation always applies to another. One could not assume, however, that ninety percent of all university students had read it.