The Kuzari Principle: Ultimate Proof of God’s Existence?

Judah Halevi (c.1075–1141), Spanish Jewish physician, poet and philosopher; author of the Book of the Khazars.

This is the first of several posts I plan to make on the Kuzari Principle, a line of reasoning often used to assert the truth of Judaism and the relative weakness of other religions.

To proponents, Kuzari provides a strong reason to believe that it would be impossible to hoax a story such as the Torah's account of the Mt. Sinai event, the National Revelation. Note that the argument concerns both the story and the event itself: Kuzari says they could not be faked and therefore both must be true.

My intent now is to give a brief and simple introduction to Kuzari. Future posts will examine Kuzari closely and assess its strengths and weaknesses as a logical argument.


What Is the Kuzari Principle?

According to Wikipedia, the Kuzari Principle

is a line of philosophic reasoning derived from the medieval work Kuzari. This principle claims to logically prove the historicity of major events recorded in the Bible from the nature of the belief in them. More specifically, it is argued that one can prove from the oral testimony of the story itself that some three million Israelites personally were led out of Egypt in an Exodus, and witnessed God's revelation to them at Mount Sinai, thus establishing the proof of the events discussed in the Torah.

David Yust views Kuzari negatively in a Talk Reason article (2002):

The Kuzari principle (KP) is a formal argument (whose ambiguous nature will be discussed further on) universally adopted by Orthodox Judaism as the sole authentic proof of the truth and exclusivity of the Jewish faith. In this sense, the KP is a materialized ideal. The invention of the KP is attributed to the famous 11th-12th century Jewish-Spanish poet and philosopher Yehudah Halevi, who allegedly formulated it in his Kuzari treatise (hence the name). Genetically, the KP may be traced to a vague sentence in the Pentateuch which enjoins the Jews to tell their sons about the Exodus from Egypt. A century after Halevi it was reiterated – again in a rather vague form – by the outstanding Jewish thinker and Pentateuch commentator Nahmanides.

In today's cyberspace, Rabbi Dovid Gottlieb appears to be the foremost champion of the Kuzari Principle. Gottlieb, incidentally, is no joke. He earned a Ph.D. in mathematical logic at Brandeis University. He was Professor of Philosophy at Johns Hopkins University. Today, as far as I know, he is a senior faculty member at Ohr Somayach in Jerusalem. Here is Gottlieb's introductory illustration (1997) to the Kuzari argument (he goes into much more detail later):

Take, for example, the revelation at Sinai. There are people who believe that the revelation at Sinai occurred. I'm not going to assume that because people believed it that it must have occurred. That is called "begging the question." However, it is a fact that there are people who believe it occurred.

Now they believe it because the previous generation taught it to them. Likewise, that generation believes it because the previous generation taught it to them. So you have a chain of generations of believers going back in time. That is a fact. The question then is, how did the chain get started? Who were the first believers? How did they arrive at their belief?

Again, oversimplifying, (this is only the outline): There are two broad possibilities. One: the event at Sinai took place and people witnessed it, and that caused their belief. Or two: the event did not take place. If the event did not take place, then someone invented the story and convinced the people to believe it.

The Kuzari's argument proceeds by investigating the second alternative, that the event didn't happen, that the story was made up and was sold. The argument shows that the second alternative is not credible. It is not credible to believe that the story was made up and then sold. If you can defeat the second alternative, that leaves only the first alternative, that it happened and was witnessed. That is the structure of the argument.

A recent application of Kuzari to the Sinai event is Betzalel Avraham Feinstein's (2009). Feinstein mentions that his post had benefited from feedback by Rabbi Gottlieb:

A) At least 600,000 Israelites gathered at the bottom of Mount Sinai over 3,300 years ago.

B) All of the Israelites heard G-d speak to them at Mount Sinai, and they then asked Moses to be His prophet.

C) Moses received the entire Torah from G-d and taught the Torah to all of the Israelites standing at Mount Sinai.

D) The Israelites transmitted the Torah and also the history of the transmission process of the Torah from generation to generation in an unbroken chain of generations for over 3,300 years until today, with at least one hundred thousand Israelites in each generation of the chain.[boldface in original]

With this background, we have a good-enough understanding of the Kuzari Principle and its application. In the next installment, I will introduce Rabbi Gottlieb's modern formulation of Kuzari.

In the meantime, feedback is invited!