Logic is an age-old science. The ability to logically convey arguments has been a sought after skill since the times of ancient Greece. Logical fallacies are arguments that fail to make sense scientifically. These arguments, which on the surface may seem compelling, are not sound from a scientific perspective. While logical fallacies can often make an emotional appeal they are arguments that do not prove the underlying claims.
There are several types of logical fallacies. Basically fallacies involve taking facts, making conclusions about those facts, and applying those conclusions incorrectly in an attempt to prove a larger premise. The scientific aspect of fallacies can be represented mathematically, but they are also studied in statistics, philosophy, and rhetoric.
There are numerous types of logical fallacies but there are a few very common ones.
Proof by example is a fallacy using one or more examples to suggest a general rule. For instance, someone might test the effects of acid on 5 rocks, and suggest that all rocks react the same to acid. That might seem to make sense but when applied differently its very obviously flawed. If one were to say 'I have seen all these people from a specific country engage in war therefore all people from that country approve of war', that obviously does not make sense.
Ad hominem is another logical fallacy. Ad hominem arguments attempt to link the validity of facts to the person presenting them. In Latin the phrase literally means arguing against the person. For instance one might suggest that because a politician is not a trained scientist his scientific information is not valid. Ad hominem arguments are common in partisan politics, where politicians attempt to dismiss out of hand claims from opponents or opposing parties based on the person or party presenting the argument rather than addressing the argument itself.
Straw Man is a term used to describe another type of logical fallacy. Basically in a straw man argument the arguer misstates, either deliberately or unintentionally, an opponent's argument, or an argument they wish to refute. At this point the arguer then challenges claims in the misstated position rather than the actual position. The name straw man comes from the idea of making a straw man, or fake position, from the real one, and debating the fake position instead of the real one.
Avoiding the use of logical fallacies is critical to credibly explaining one's position. Further observers to a discussion will often pick up on the use of fallacies and may attribute deliberate deceit even to innocent logical mistakes. The following are ways to avoid using logical fallacies.