Shakespeare uses "et tu Brute", or "you too, Brutus", as spoken by Caesar as he is being stabbed to death, There is no evidence he said this, but some reports have something similar being said by Caesar.

A play by John Cook in the 1600's is called "Green's tu quoque" or "The city gallant".

Here is the "tu quoque" fallacy in abstract terms.

• 1. Person A claims that X is true.
• 2. Person B shows that A's behavior contradicts claim X.
• 3. Person B claims that X is false.

Let us look at this in diagram form.

• 1. Person A clams that X is true.

• 2. Person B shows that A's behavior contradicts claim X.
• 3. Person B claims that X is false.

As a matter of (logical or reality) truth, claim "X" is true or false in spite of what person "A" believes or says or does.

The saying of a hypocrite is "do as i say and not as I do".

However, in terms of the "tu quoque" logical fallacy, one must evaluate the "say" without being influenced by the "do".

The "say" may be "true". The "say" may be "false". The "do" should not directly dictate whether one takes the "say" as "true" or "false".

Here is another way to understand this concept.

There are some cases where the hypocrisy may be relevant to the claim.

There are other cases where the hypocrisy is not relevant to the claim.

This is the fallacy. More analysis is needed.

This was a logical problem for the self-esteem movement.

• Some children whose self-esteem was protected turned out bad.
• Some children whose self-esteem was battered turned out good.

Thus, the self-esteem idea is a descriptive model after-the-fact and not a predictive model before-the-fact.

Details are left as a future topic.

Logic fallacies are studied because so many people believe that the fallacies are actually good reasoning. Some people get very upset if you question their reasoning, even if it is well known (in the field) to be faulty reasoning.

Fields such as marketing and politics and other fields often use logic fallacies to deceive and manipulate people.

Here is a concrete example of the "tu quoque" logic fallacy.

• 1. Person A claims that "smoking is bad".
• 2. Person B shows that person A smokes.
• 3. Person B concludes (or implies) that "smoking is not bad".

Often, the last part is omitted and is just implied.

• 1. Person A says "You are driving too fast".
• 2. Person B says "You drive too fast all the time".

The last part, that person B is not driving too fast is left implied.

A version of the "tu quoque" logic fallacy is the logical fallacy of the "pot calling the kettle black".

It arises from pointing out that a person is guilty of the same offense that that person is accusing others. This is a form of psychological projection or hypocrisy.

The "pot calling the kettle black" logic fallacy appears to be of Spanish origin from the 1600's and appears in Thomas Shelton's 1620 translation of Don Quixote and appears as a Spanish idiom.

There are words and phrases that have similar meanings to the "tu quoque" logic fallacy.

• Pot calling the kettle black (see above)
• Those who live in glass houses should not throw stones
• Whataboutism - accusing others of the same behavior
• Accusation in a mirror
• Clean hands

Interestingly, it appears to be hard to find a definite reference for quotes such as this.

This may be because he may have made statements somewhat like this, but any quote about discounting Christianity because of the behavior of some Christians would fall under the "tu quoque" logic fallacy.

If only non-sinners were allowed in church, to avoid apparent hypocrisy, there would be no one in church and no church!

Some churches will expel members if any sin is detected or becomes known, etc.

In addition, the wrong type of example may, in fact, be an indicator of more serious issues inside the person setting the bad example. It is prudent to verify what might be deceptive.

Here are some examples of people who said things, via demonstrative and mathematical proof, that they did not believe at the time or, after the implications become more obvious, denied that applicability.

Should one go by their beliefs or what they said?

Thus is the tu quoque logic fallacy. One should evaluate what they said without being influenced by what they might have said later about what they said earlier.

Gregory Chaitin, co-founder of Algorithmic Information Theory (after he developed his ideas, he discovered that Komolgorov had done similar work) proved that one cannot construct a computer program to determine if a sequence of numbers is random. Instead, one must be informed of this from outside the system.

It appears that after the creation implications of his proof became apparent, that this implies a creator god outside of time and space, he felt compelled to write a book attempting to support the theory of evolution.

Details are left as a future topic.

Here are some reflexive relationships that may not fit into the tu quoque logic fallacy. Remember, a logic fallacy is not always true or false. That is the point. A logic fallacy is that something that is not always true or false, but many believe that the fallacy is always true or always false.


That is, they may start believing their own lies.

Can both the casting out the beam and casting out the mote (twig) analogy be taken reflexively? In the verse, casting out the beam was stated reflexively but removing the mote (twig) was not.

This appears to make sense but appears to require that a beam and a mote (twig) represent different ideas (which was the conclusion reached anyway). The idea with the reflexive casting out of the mote (twig) as that one can create rules and requirements that paralyze oneself. One should not even think about such casting out but, instead, rethink what is required and just do that - bearing fruit on the mote (twig) that was neither removed nor altered nor constrained.