Please excuse my delay in answering your letter.

First of all, let me stress that the thirteen principles by which the Torah is explained, are not Rabbinical, either in their conception nor in their application. In fact, they are Halachah le'Moshe mi'Sinai. Consequently, if the Gemara writes that one cannot learn a Kal va'Chomer from a Halachah etc.,(and according to Rashi, this extends to all the thirteen principles), that means that this is what Hash-m told Moshe at Har Sinai. The reason for this would appear to be that the thirteen principles were handed down to Moshe as a key to decipher the secrets locked away in the written Torah.

The written Torah itself was given to us deliberately in such a way that what is obscure in the the Written Torah, is explained in the other.

The Halachos le'Moshe mi'Sinai, which were dictated to Moshe orally, were given to him with such clarity, that they were not subject to any interpretation or explanation. Hash-m said exactly what he wanted to say, and He did not expect His words to be extended. That interpretation goes well with Rashi's P'shat.

According to the Ramban (quoted in the Yefei Einayim there), who writes that the Gemara's principle applies to a Kal va'Chomer, but not to a Gezeirah Shavah, we will be forced to amend the above explanation slightly. We will have to say, either that a Kal Vachomer, having to rely, as it does, on man-made logic (for which reason - according to some - we do not apply a Kal va'Chomer in order to apply the death-sentence), is different, inasmuch as it is confined to infer from the words of the written Torah, not to a Halachah etc.; whereas all other principles apply to Halachos le'Moshe mi'Sinai as well.

Alternatively, we could say that generally, we do not apply any of the thirteen principles to Halachah le'Moshe mi'Sinai - with the sole exception of a Gezeirah Shavah. Why should a Gezeirah Shavah be different? Because a Gezeirah Shavah, unlike all the other principles, can only be learnt if it was handed down to Moshe at Sinai. Consequently, if Hash-m handed it down to Moshe at Har Sinai, that means (Kevayachol), that He wanted us to make the derivation in this case, so we do!

Perhaps we can even add a little spice to this idea, by saying that the Gezeira Shavah itself is Halachah etc., so why should we not use it to expound on a Halachah?

Finally, you ask why the Gemara itself apppears to violate this fundamental rule? When we consider that the rule is being laid down by Rebbi Akiva, who is in the process of rejecting his Rebbe, Rebbi Eliezer's contention, then that point is self-explanatory; Rebbi Eliezer does not agree with Rebbi Akiva's disproof, and it is Rebbi Eliezer's opinion that the Gemara initially quotes.

Thank you for your questions. I hope that my remarks will shed some light on the Sugya in question.

b'Virkas Kol Tuv,

Eliezer Chrysler