Kettle logic originally comes from “Interpretation of Dreams” and refers to a person who holds a position, using multiple arguments to defend that position, when his arguments are internally inconsistent.
The original example given by Freud is one where a man is accused to returning a kettle he borrowed from a neighbor in damaged condition and he then uses 3 arguments to defend himself:
- He returned the kettle undamaged.
- The kettle was already damaged when he borrowed it.
- He never borrowed the kettle.
As you can see, each of these arguments by themselves are acceptable. However, argument 3 is inconsistent with arguments 1 and 2. He could not have returned the kettle if he never borrowed it, and in argument 2 he states that he did in fact borrow the kettle.
This is also what Epicurius saw when he came up with what has become known as the “3-O” argument or “The problem of evil”. Wherein god cannot be omnipotent, omniscient and omnibenevolent. In that if God is all of those three, then why is there evil in the world?
Kettle logic is usually one of the harder fallacies to spot, especially if you are not paying full attention. If combined with a flurry of argumentation, and arguments that are obfuscated so as to avoid being clearly contradictory a speaker can easily give the impression of having a lot of arguments at his disposal, despite the fact that they all contradict each other.
One thing that is often not mentioned is “Kettle citations” this is where someone cites a lot of sources in their argument, yet the sources may contradict each other on important points, while superficially giving the impression of a strong case. This is a phenomenon I’ve experienced quite a lot in debates on religion, where a believer will often cherry pick verses or quotations from a work in order to defeat the argument you are presenting that at moment.
For instance, they may cite the new testament if you are criticizing the somewhat harsh and unforgiving god represented in the old testament, and revert to quoting the old testament when the topic changes to homosexuality.