Make for yourself a rav

 

רבן גמליאל אומר עשה לך רב. והסתלק מן הספק. ואל תרבה לעשר אומדות. זה אשר צוה הנה לעשות רב אינו לענין הלמוד אבל להוראה שים לך רב שתסמוך עליו באיסור והיתר והסתלק אתה מן הספק כאמרם בירושלמי זיל אייתי לי זקן מן השוק דאסמוך עליה ואשרי לך וכן צוה שיברח מהוצאת המעשרות באומד מפני שהוא מן הספקות:

Rabban Gamliel says, "Make for yourself a mentor, remove yourself from doubt and do not frequently tithe by estimation." That which he commanded here to make a mentor is not regarding study, but rather legal decisions: place for yourself a mentor, that you can rely upon in the forbidden and the permissible, and you can remove yourself from doubt. [It is] as they say in Talmud Yerushalmi Moed Katan 1:10, "Go and bring me an elder from the marketplace and I will rely upon him and permit [it] to you." And so [too] did he command to flee from putting out tithes by estimation, because it is from the doubts.

Rambam on Pirkei Avot 1:16:1 with Connections (sefaria.org)

The Mishnah says, “Make for yourself a rav and remove yourself from doubt.” (Avos 1:16) The Rambam comments, “This command to appoint yourself a teacher is not for the sake of learning but for deciding questions of halacha. You should establish an authority that you rely upon concerning what is permitted and prohibited and thus remove your doubts.” Rambam, Pirkei Avos 1:16. The Rambam can be explained with the Ramban. The latter said that when he comments on the Behag, he doesn’t speak with absolute certainty as if there were absolute proofs for his arguments. (Milchamos Hashem, intro.) He offers what he considers the more likely answer. In other words, you are never free from doubts, even in halachic matters, and certainly not in learning up a sugya or discussing philosophy. Thus, “Make for yourself a Rav,” isn’t addressing Torah study. It concerns technical shilas where you are removed from doubt only because you are consulting an expert on what action to take concerning the technical matter. As the Mishnah in Horoyos tells us, an individual is exempt if he performs a transgression as a result of an error in a court's ruling. So you are removed from doubt because the responsibility is on the court.

Thus the Mishnah in Avos can’t be a call to get your entire life philosophy from one person because every person is different as the Gemara says “whose minds are unlike each other and whose faces are unlike each other.”  Berachot 58a. So trying to get your life outlook from a person who is different from you will leave you with doubts.

Furthermore, Rabbi Joseph Soloveitchik said that a sefer is also a rav. Today we have so much printed material that the principle of not poskening in front of your rav also applies to books. When people asked Rabbi Soloveitchik a question, he’d say I must get back to you because if he answered on the spot, it would be like poskining in front of his rav. He consulted his books. If you have a question such as may you hand a curtain in a shul on Shabbos as a mechitza, the book 39 Melachos answers yes. That is consulting a rav. If you asked the rav down the block, he might also consult that book.