Ever since Epimenides the Cretan (7th century B.C.) declared that All Cretans are liars, the notion of self-reference became synonymous (and often erroneously) with that of paradox. However, most ubiquitous self-reference which happens each time somebody says "I", is harmless. Following are a few gems from Metamagical Themas.
- Thit sentence is not self-referential because "thit" is not a word.
- If this sentence didn't exist, somebody would have invented it.
- This is not a complete. Sentence. This either.
- This sentence will end before you can say "Jack Rob
- Does this sentence remind you of Agatha Cristie?
Raymond Smullyan lists what he calls self-annihilating sentences from a collection by Saul Gorn "S. Gorn's Compendium of Rarely Used Cliches." :
- Before I begin speaking, there is something I would like to say.
- I am a firm believer in optimism because without optimism, what else is there?
- Half the lies they tell about me are true.
- Every Tom, Dick, and Harry is called John.
- Having lost sight of our goal, we must redouble our efforts!
- I'll see to it that your project deserves to be funded.
- I've given you an unlimited budget, and you have already exceeded it!
- A preposition must never be used to end a sentence with.
- This species has always been extinct.
- Authorized parking forbidden!
- If you're not prejudiced, you just don't understand!
- Inflation is an economic device whereby each person earns more than the next.
- Superstition brings bad luck.
- That's a real step forward into the unknown.
- You've outdone yourself as usual.
- Every once in a while it never stops raining.
- Monism is the theory that anything less than everything is nothing.
- A formalist is one who cannot understand a theory unless it is meaningless.
How many mistakes are there in the sentence: 'This sentance contanes one misteak'? What is the answer to the same question for this sentence: 'Their are three misteaks in this sentence'?
From the wonderful Beyond Numeracy I gleaned the following two pearls
- There is the case of the voter who when asked by a pollster what were the reasons for the ignorance and apathy of the American public, responded, "I don't know and I don't care."
- What is the question that contains the word cantaloupe for no apparent reason?
Lest you form a self-defeating impression that thinking up self-referential sentences is an exclusive pastime of self-indulgent mathematicians, I'll cite from a small book by William Safire
- Don't use contractions in formal writing.
- Do not put statements in the negative form.
- Avoid run-on sentences they are hard to read.
- Verbs has to agree with their subjects.
- Avoid trandy locutions that sound flaky.
A subtlety from the Littlewood's Miscellany:
E.Harrison: "Is it true that philosophy has never proved that something exists?" Bertrand Russell: "Yes, and the evidence for it is purely empirical."
The following comes from A Whack on The Side of The Head by R. von Oech
Every rule here can be challenged except this one.