In a valid logical argument:
- If ALL of the premises are true, then the conclusion must be true.
- If ANY of the premises are false, then a valid logical argument may still lead to a false conclusion.
An invalid or unsound argument:
- Does not necessarily prove the conclusion false, just that it is not necessarily true.
- It is possible that an argument that uses incorrect information or faulty logic can still result in a conclusion that happens to be true.
A logical fallacy is a reasoning flaw.
Not only must the factual data that is part of a premise be valid, but the reasoning used to employ those facts must not contain reasoning flaws – logical fallacies. For those unfamiliar with logical fallacies, below are some common logical fallacies taken from Thou Shalt Not Commit Logical Fallacies which is a great reference source.
False Cause – The presumption that a real or perceived relationship between things means that one is the cause of the other.
Texas Sharpshooter – Cherry-picking a data cluster to suit the argument or finding a pattern to fit a presumption.
Appeal to Authority – Saying that because an authority says something, it must therefore be true.
Appeal to Emotion – Attempted manipulation of an emotional response in place of a valid or compelling argument.
Strawman – Misrepresenting someone’s argument to make it easier to attack.
Ad Hominem – Attacking an opponent’s character or personal traits in an attempt to undermine their argument.
Loaded Question – Asking a question that has a presumption built into it so that it can’t be answered without appearing guilty.
Ambiguity – Use of a double meaning or ambiguity of language to mislead or misrepresent the truth.
Bandwagon – Appeal to popularity as an attempted form of validation.
Black-or-White – Presenting two alternatives as the only possibilities when more possibilities exist.
Anecdotal – Using a personal experience or isolated example instead of a sound argument or compelling evidence.
Slippery Slope – Asserting that if we allow A to happen, then Z will eventually happen too, therefore A should not happen.
The Rules of Engagement
Logical fallacies can be used unintentionally or intentionally. For example:
- Politicians do it to get support and votes.
- The media does it to get viewers, readers, etc. in order to sell ad space.
- Advertisers do it to sell their products.
- Individuals do it to convince others of their opinions.
For the purposes of Runaway Logic, we should endeavor to avoid logical fallacies.