If you think this is my first blog about liars, it is. On September 19, 2019, I posted a blog entitled The Ethics of Writing Lies. The opening paragraph was metaphorical, as in “beating a dead horse.” 

“What could be ethical about lying? How could any writer write lies and think it was ethical? Well, it depends on what kind of lies. Whose lies are being told? Yours? Someone else’s lies? White lies? Save-a-life lies? Damn lies? Big fat lies about your ex? Lies you are sure are not true, but turn out later to be true? Does timing make a difference? Do the circumstances matter?”

This blog is a philosophical distant cousin to the questions I asked in that last blog. Now I’m asking the question philosophically rather than metaphorically. One version of the Liar Paradox comes from a Greek philosopher, Eubulides of Miletus. He asked a simple question of learned folk in the 4th century BC. “A man says that he is lying. Is what he says true or false?”[1]

If Eublides’s liar is actually lying, then he’s telling the truth, right? That means the liar just lied. Here’s the proof: in “this sentence is a lie,” the paradox is strengthened in order to make it amenable to more rigorous logical analysis. It is still generally called the “liar paradox” although abstraction is made precisely from the liar making the statement. Trying to assign to this statement, the strengthened liar, a classical binary truth-value leads to a contradiction.[2]

The first sentence in this blog is a lie. I hate to say that, given that I wrote it to you. It feels odious. Remember that all lies are untrue. Is the first sentence true? If it is, then it is a lie, and so it is not true. Conversely, suppose that it is not true. I’m the author. I wrote it. Normally, I write words with the intention of being believed by my readers. Writing something that way when it is untrue is a lie. But then, given what the sentence says, it is true after all.

Let me give you five paradox examples I copied from someone else’s writing.[3]

  1. I always lie.
  2. Nobody goes to that restaurant; it’s too crowded.
  3. Don’t go near the water until you have learned how to swim.
  4. Let the God Almighty create a stone, which he is not capable of lifting!
  5. The man who wrote this list of paradoxes cannot write at all :-).

These paradoxes can easily be proven true, which rectifies the contradiction. Sometimes they are just play on words. Others cannot be universally accepted as resolutions. Does that give truth to the lie or vice versa? Only Yogi Berra knows the answer.

If “this sentence is false” is true, then it is false, but the sentence states it is false, and if it is false, then it must be true, and so on. The challenge in the Liar’s Paradox is elusive. On the surface, it seems to prove that common beliefs about truth and falsity actually lead to a contradiction. Sentences can be constructed that cannot consistently be assigned a truth-value even though they are completely in accordance with grammar and semantic rules. Writers who write like that give me a headache. I believe them until I don’t. Then I contradict them and end up believing them. Again. Where’s my acetaminophen, which is also known as Tylenol. Is that a liar’s paradox?

We cannot ask the previous president about this. His life resembles the Liar’s Paradox, and Yogi Berra would have spotted it right off.

Gary L Stuart

I am an author and a part-time lawyer with a focus on ethics and professional discipline. I teach creative writing and ethics to law students at Arizona State University. Read my bio.

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[1] https://en.wikipedia.org/wiki/Liar_paradox

[2] Ibid.