halacha - Are seemingly hashkafik texts like Pirkei Avot and Rambam Hilchot Deot halachikly binding?

A surface read of Pirkei Avot and Hilchot De'ot would suggest that their contents appears to be primarily advice as to how one should proceed over and above the minimal halachik requirements. Nonetheless, these two respective works are codified among primarily halachik series, the Mishna and Mishna Torah respectively.

Do the instructions provided in these two volumes (and other volumes that fit my aforementioned criteria) contain halachik weight for anyone or everyone? Are they codes to teach us how to behave should we wish to go beyond the letter of the law? Are they simply there to enrich our lives?

Answer

Rambam Hilchos De'os is halachikally binding except where the Rambam specifically states that it is limited to a Talmid Chacham (e.g. chapter 5). Hilchos De'os contains the specification of no less than 11 Biblical mitzvos including the prohibitions against revenge and lashon hara and these commandments are certainly obligatory.

The portions that deal with treating others properly like greeting others pleasantly (sever panim yafos) are included in the mitzvah of emulating Hashem and are also binding. See 1:5 where this is explicitly stated by Rambam.

Similarly, Pirkei Avos, in general, applies to everyone; note that the Ein Mishpat (found in Vilna Shas end of Maseches Avodah Zara) has numerous footnotes citing the passages in Rambam and Shulachan Aruch that are based on the referenced mishna. In addition, in many Halachic contexts Tosfos on the Gemara (e.g. Rosh Hashana 4a s.v. Beshvil) raises questions from Avos (but also see Tosfos Yom Tov ibid and rambam end of hilchos teshuvah) who clearly maintain that this is not required but is certainly optimal). (Of course, some mishnayos in Avos were intended for Talmidei Chachamim e.g. 1:1 Shimon Hatazdik etc) Some mishnayos are intended as not required advice (). One has to see how the Poskim (e.g. Rambam, Shulchan Aruch, etc) understood those comments to determine if they are binding or simply advice.(e.g. Avos 1:5 "al tarbeh sichhah" and Rambam Hulchos De'os 5:4)

Your question is similar to the one raised by the Chofetz Chaim in his introduction to that sefer where he asks whether Rabenu Yonah's Shaarei Teshuva is halachically binding. Chofetz Chaim clearly understands that Rambam in Hilchos De'os is binding as he quotes from it extensively throughout his sefer. As a matter of fact, the issur for lashon hara is found in Hilchos De'os!