Via Fallacy Files:

The name “argumentum ad baculum” alludes to the use of a stick, or club a “baculum” was a walking-stick or staff to beat someone. As a logical fallacy, “ad baculum” or “appeal to force” applies to the use of force and, by extension, the use of threats of force to “win” a debate.

There are two types of logical error that may be involved in appeals to force:

1. Some appeals to force may be appeals to the consequences of a belief. What sets the appeal to force apart from other appeals to consequences is that the bad consequences appealed to that is, the use of force will be caused by the arguer. Attempts to change people’s minds by threats of punishment are appeals to consequences, since the bad consequences appealed to are not consequences of what is believed, but of the belief itself. As such, they are irrelevant to the truth-value of the belief.

However, because it is impossible to read a person’s mind, the attempt to use force or threats to change minds is usually ineffective. Instead, threats are more commonly reasons to act, and as such can be good reasons to do so if the threat is plausible. People are sometimes intimidated into pretending to believe things that they don’t, but this is not coming to believe something because of the fear of force. So, appeals to force which are appeals to consequence may fail one criterion of a logical fallacy, namely, that it be a common type of bad argument.

2. When force or the threat of force is used to suppress the arguments of one side in a debate, that is a type of one-sidedness. Governments are always tempted to use police powers to prevent criticism of their policies, and totalitarian governments are frequently successful in doing so. Extremists use threats or actual violence to silence those who argue against them. Audience members “shout down” a debater whom they disagree with in order to prevent a case from being heard. This is, unfortunately, common enough to qualify as a logical fallacy.

However, force or the threat of it is not an argument, which means that appealing to force is not a logical fallacy. Since hitting someone over the head with a stick is not an argument at all, a fortiori it is not a fallacious one. However, withholding relevant information can lead people into drawing false conclusions.

For these reasons, calling the appeal to force a “logical fallacy” is misleading. More accurately, it is a logical boobytrap, that is, a way of tricking someone else into reasoning incorrectly.

See also:

• Volcanic Tempers: Crazed John McCain Attacked Rick Renzi With Bare Hands!
• New Book: McCain Once Physically Attacked Fellow Congressman
• The Real McCain: Fighting Words and Flip Flops