Shaving with a Razor - Taam HaMitzvah

The Tur in Yoreh Deah Siman 181 quotes the Rambam who gives a reason behind the issur of shaving with a razor. The Rambam says that the reason behind this prohibition is that since it was the way of idol-worshippers to shave in this fashion therefore the Torah prohibited it. (See Rabbeinu Bachya VaYikra 19:27 for some different approaches.) The Tur questions the need for the Rambam to give the taam hamitzvah at all. Aren't all mitzvos obligatory regardless of the reason behind them? (See the commentators on the Tur who address his argument.)

In general this Rambam does pose a difficulty because it is found in Mishneh Torah. Generally, the Rambam reserves taamei hamitzvah for the Moreh Nevuchim. Why did the Rambam feel it was necessary to state the taam hamitzvah for shaving with a razor?

I believe the answer is simple. The Rambam places the halachos of giluach hazakan in Hilchos Avodah Zarah Perek 12. Therefore, the Rambam has to justify this placement. Imagine if the Rambam hadn't written that these laws of shaving were due to the practices of idol-worshippers. The question would jump off the page! What in the world are halachos of shaving doing in Hilchos Avodah Zarah??

This highlights the general difference between the way the Rambam categorized halachos and the way the Tur did. The Tur divided everthing into four basic sections - Orach Chaim, Even HaEzer, Choshen Mishpat, and Yoreh Deah. Let's take Yoreh Deah as an example. It is essentially is a collection of issur v'heter. The different issurim dealt with in Yoreh Deah are not necessarilly related to one another. Shaving and Kashrus don't really go hand in hand. The same can be said for Orach Chaim. The Rambam placed Hilchos Shabbos and Hilchos Tefillah in totally different sections of Mishneh Torah. But in the Tur they are all part of Orach Chaim.

The categories that the Rambam created were not merely meant for convenience. They were meant to describe the essential nature of the halachos. Hilchos Tefillah for example is in the section Ahava - Love. By placing Hilchos Tefillah in Ahava the Rambam is telling us something about the nature of Tefillah. Tefillah has to do with loving the Creator. The Tur, on the other hand, places Hilchos Tefillah in Orach Chaim - laws that have to do with day to day living. The Tur is noting a characteristic of Hilchos Tefillah - but he is not attempting to describe the basic nature of Tefillah.

In the Tur's division of the halachos shaving isn't part of any broader area of halacha. It is simply it's own category - the laws of shaving of the beard. In the Rambam shaving belongs to the broader category of Hilchos Avodah Zarah. Hilchos Giluach HaZakan does not merit its own section in the Rambam's Mishneh Torah.

We'll just conclude by noting the obvious - that the goal of the Baal HaTurim in writing the Tur was totally different than the goal of the Rambam in writing Mishneh Torah. The Baal HaTurim was concerned with recording the practical halacha l'maaseh so people would know what it is they were supposed to do. That is why he divided the laws into four sections which would be intuitively searchable to the laymen. If I want to know how to live my daily life I'll check Orach Chaim. If I want to know about money matters - Choshen Mishpat. That's also why the Tur left out all the laws that don't apply nowadays. The Rambam on the other hand was interested in recording - in an organized fashion - all of Torah Shebaal Peh. The categories weren't created for the purpose of easily finding out what to do - but rather they were created to help understand all the details within their broader context.