Lewis Trilemma

While some religious apology is magnificent in its limited way — one might cite — and to some it is dreary and absurd — here one cannot avoid naming C. S. Lewis — both styles have something in common, namely the appalling load of strain they have to bear. How much effort it takes to affirm the incredible. The Lewis Trilemma is a fallacious apologetical argument for the divinity of Jesus, invented 1844 by preacher  (published 1846 in Lectures on the Evidences of Christianity ) and popularized by C. S. Lewis on BBC radio, hence the name of the trilemma.

The argument is also known as "liar, lunatic, or Lord," "mad, bad, or God," or "myth, madman, or messiah", referring to the three given parts of the Trinity trilemma— a three-way false dilemma.

Lewis's own statement of the argument
Lewis wrote in Mere Christianity:

Note that his own words appear to undermine premise 3 of his argument below, which relies on Jesus being a great moral teacher to rule out the possibility of his being a lunatic. It's also noteworthy that his final statement, which he tries to make sound like a conclusion he came to reluctantly, bears all the hallmarks of being precisely the conclusion he wanted to reach.

Lewis does not seem to countenance the option of accepting some facets of Christ but not others. This is akin to saying that if you accept that Martin Luther King was a great man, you must accept that cheating on your wife is perfectly fine. Lewis also ignores the option that some of Jesus' words and claims may have been altered when they were reported.

Lewis' formulation of the argument does not intend to prove the divinity of Jesus (although Lewis believed in it) but merely the impossibility of accepting Jesus as a moral teacher while refusing his claims to divinity.

The logic of the argument
Assuming Jesus claimed to be God, Lewis' thoughts can be summed up as follows:

1. Due to the law of the excluded middle, Jesus was either correct or incorrect in his claim of divinity. He also either believed or did not believe he was divine. Therefore one of 1A, 1B, 1C, or 1D applies to Jesus:


 * 1A. Believed He was God and was correct in His belief (Lord).
 * 1B. (lunatic).
 * 1C. Did not believe He was God but actually was God (ignored as a possibility).
 * 1D. Correctly believed he was not God because he wasn't God (liar).

From this, Lewis gets:  Jesus spoke out against liars, so he was either a hypocrite, or he was not a liar. Jesus did not show any other signs of being deranged, being a great moral teacher, so he was not a lunatic. Everybody who knew about Jesus paid attention to him. Therefore, you must believe Jesus was God or completely reject Him. 

Additional points by other authors
Josh McDowell writes:

Hidden premises
The above argument holds a few hidden premises beyond the ones given outright by Lewis. These hidden premises include:
 * 1) The Abrahamic God exists.
 * 2) Jesus existed.
 * 3) The Gospels are an accurate record of Jesus' life and teachings.
 * 4) Jesus (and people in general) are of homogenous character and cannot contain contradictory or opposing aspects within their person.

These hidden premises appear when we formalize the trilemma, and all can be challenged or undermined, with the last one breaking the logic altogether. Anyone with any non-zero amount of social activity has tons of experience encountering good and bad facets in themselves and others. Even young children can remember cases where they or someone else contradicted themselves.

There are a further 2 points:
 * 1) If Jesus existed, it is assumed that all the sayings attributed to Him were by Him. If the preachings of many men were attributed to Jesus, some may have been mentally unstable and/or liars.
 * 2) Any false accounts could have been added to the narrative during the decades of before the Gospels were written down.

Delusion
There are also more problems with the argument beyond these alone. Step 3 in the argument can be challenged, as Jesus may have had that one delusion of the false belief of auto-divinity but been otherwise okay, much like how Isaac Newton was an alchemist and tried to find messages in the Bible, but otherwise made great contributions to science.

Did Lewis overestimate how deluded a person who saw himself as God would have been in ancient Judea? The concept of a human as God is totally unacceptable in Judaism, but in the Greco-Roman religion, men can be gods. The Roman emperor was, for example, seen as a man and a god.

Morality
One could disagree with the claim of Jesus being a great moral teacher. A great deal of Christian morality is about inducing guilt and reducing self-respect. The teachings of Jesus have been used to justify widely divergent belief systems, like Christian communism, Christian economics, and Liberation theology. The teachings of Jesus' followers were used to justify the Spanish Inquisition and various other persecutions of those considered heretical by various Christian orthodoxies. In the United States, they were used at least as much in favor of slavery as they were for its abolition. How the moral teachings of Jesus are interpreted is greatly affected by how later Christians developed what is in the New Testament.

In Lewis' specific version of the trilemma, it is not apparent how Jesus would not have been a great moral teacher simply because he falsely believed himself to be God and for no other reason. This blends with the above paragraph: Newton practiced the pseudoscience of alchemy, yet that did not make his contributions to actual science any less valuable. Many great moral teachers had significant flaws: Aristotle justified slavery; Kant was an anti-semite; JS Mill an imperialist and racist; to say nothing of Mohammed, Nietzsche, or Shaw.

The true essence of the argument is that Lewis, in reading the words attributed to Jesus in the Gospels, simply had the subjective opinion that it did not seem like they could have come from anyone but God, and the rest of the argument is mere window dressing around that core.

Tetralemma
Our fourth, ignored possibility — of Jesus not knowing he is God — also shows up. It isn't enough to refute the trilemma beyond turning it into a "tetralemma" and is little more than a triviality due to the confusing implications that nobody, either theist or atheist, has explored in depth. That possibility isn't part of the established story, and no one has made the claim (that we know of). Beyond that, Jesus claims his relation to divinity multiple times throughout the Bible, though they all appear to be in arrears of other people claiming it.

In Narnia
A version of the trilemma appears in Lewis' fiction book The Lion, the Witch, and the Wardrobe in the Narnia series. After Lucy visits Narnia through a magic wardrobe and tells her siblings, they dismiss her story. Later, one of her brothers enters Narnia with her, but when they come back, he denies the story to the older two. This prompts the older two siblings to voice their concerns about Lucy to the owner of the house where they are staying. However, the owner, a professor, argues that since Lucy is neither dishonest nor insane, her story must be true. This shows both the absurdity of the argument and the disingenuity in employing it (the man had already visited Narnia, and thus this argument wasn't his true reason for believing Lucy, just as Christians have other reasons for believing in Christianity).

In fairness, the professor was referring to a specific single claim of Lucy, not to the broader worth of all of Lucy's musings. Lewis' argument works if you only look at Christ's claim to be God — He was either lying, if He did not believe it, delusional, if He was incorrect in believing it, or actually God. In addition, Lewis may not have decided at the time that the professor had been to Narnia before, since the book where he and a friend witness Narnia’s creation as children was written several years after this one.

Hitchens
Within his book God Is Not Great: How Religion Poisons Everything, Christopher Hitchens claims to be refuting Lewis, but basically follows the same fallacy (only Hitchens applies it to the entire Gospels)