It's Irrational to Add

The Torah not only forbids adding (Deut 4:2), but it also gives a rationale for a steady state Torah. In the same chapter, only a few verses later, we see:

6 Observe therefore and do them; for this is your wisdom and your understanding in the sight of the peoples, that, when they hear all these statutes, shall say: 'Surely this great nation is a wise and understanding people.'

8 And what great nation is there, that hath statutes and ordinances so righteous as all this law, which I set before you this day?

It was Maimonides who famously commented on v. 6 that a Torah law must , by virtue of this verse, be rational, and not conflict with the intellect. Now, it is true that Maimonides goes on to blaspheme the Torah and make a pig's ear of a justification for the oral law. He is also notably silent on the irrationality of the rabbinical fairy tales called “halacha”. However, his bounded rationality was demonstrated in his attack on astrology and superstition that was rife in Talmudic lore. He even takes issue with the astrologers of the Talmud.

Had the Rambam been logically consistent, and pointed out the various contradictions between the Talmud and the Torah, he would effectively be a Karaite. This far, he did not go. But the logic is still valid. The Torah says that these Torah laws are our wisdom in the eyes of the world. How then, can the rabbis flout almost every word of the Torah, and get away with it?

There are some empirical facts which are inescapable:

The entrance of Pharisees on the world stage, around 150-200BCE led to the greatest disaster in Jewish history. They ransacked the Temple and its practices, and introduced their own bastardised version. This inevitably led to the destruction of the Temple and a 2000 year exile. It is also ironic that the Torah itself has been widely accepted by the nations of the world, whereas the Talmud has largely been viewed with derision. Would the Talmud have been so vilified if it was really part of the Torah? The Torah itself claims that the Written Law is “ your wisdom and your understanding in the sight of the peoples, that, when they hear all these statutes, shall say: 'Surely this great nation is a wise and understanding people”.

So adding to the Torah is both forbidden, and also irrational, by the internal logic of the Torah itself.