An informal fallacy is an error in reasoning that does not originate in improper logical form. Arguments committing informal fallacies may be formally valid, but still fallacious. An error that stems from a poor logical form is sometimes called formal fallacy or simply an invalid argument. There are many different informal fallacies, but a few basic types. For instance, material fallacies is error in what the arguer is talking about, while Verbal fallacies is error in how the arguer is talking.