Commento su Pirkei Avoth 4:8

DO NOT JUDGE A CASE ALONE. Rav writes that this even applies to a single expert judge, who is authorized to judge cases alone, as Rav writes in Sanhedrin 3:1. [*Rav also writes: but if the litigants accepted him as a judge, even one who wishes to act piously can judge the case alone. I don’t see the logic here, for even in this case it is better to work the ruling out with others. Additionally, when there are three judges the litigant who is ordered to pay doesn’t know which of the judges decided against him; in considering each judge individually, he can always assume that this judge ruled in his favor but was overruled by the other two. Maharil uses this in the Likutim to explain Shmuel's saying¹⁵⁵Sanhedrin 3a. that although the ruling of a court that convenes with only two judges is valid, the court is called a “brazen court”: they are brazen and do not care that the litigant they order to pay will know that neither of them ruled in his favor.
Indeed, Tur writes at the beginning of Choshen Mishpat 10 that “through much back-and-forth, the judge will penetrate to the depth of the case.” The word “back-and-forth” usually means discussion with another person, not internal back-and-forth, and it does not seem reasonable to distinguish between expert and non-expert judges in this respect.

He would say: Do not judge alone: This is also from the matter of withholding oneself from judging. As even though an expert (judges) even alone, it is [of] the trait of piety that he not do so but [wait] until he takes colleagues that judge with him and they will help him. And it comes out a little that he withholds himself from judging, as not all [of the judging] is placed upon him.

The Torah permitted an expert [known] to the public to judge by himself, as we explained in Sanhedrin. But this is the word of the Torah and here it warns him a little from the angle of ethics and not from the angle of prohibition. And he said [that] if your colleagues disagree with you in an opinion from the opinions, do not force them to accept your argument - as they know if they must accept it, and it is not your right to force them to accept your opinion.

And I do not know [Rabbi Bartenura's] reason, since it is nonetheless better for him to make the judgment in a group; and also if they are three, the convicted will not know who convicted him. And see Tosafot Yom Tov.

"Don't be a lone judge": Even though an expert may judge alone, it is from the way of piety that even an expert should not judge alone. [And that is] only when the litigants have not accepted him upon themselves as a judge; but if they accepted him upon themselves, he can judge alone even in the way of piety.

He used to say: judge not alone, for none may judge alone save one. And say not “accept my view”, for they are free but not you. According to the rabbis, the Torah does permit an expert judge to judge alone. Nevertheless, Rabbi Ishmael warns judges not to do so, for only God can truly judge alone. Human beings, even those who are expert in law, should set up courts of three, as is described in Sanhedrin, chapter three. When this expert judge is sitting with two others, and they disagree with his decision, he may not say to them “accept my view”. He may not use force, even verbal force, to get them to acquiesce to his own view. “For they are free but not you”, means that since they are the majority, they may compel you to accept their, majority decision. You, even though an expert, cannot compel them to accept your, minority decision.

for there is no lone judge aside from One [God]: He wants to say that there is no lone judge except for the Holy One, blessed be He. And there is [someone] who explains, "for there is no lone judge aside from one" [that] this is the expert, but not other people who are not experts. And therefore a person should not consider himself an expert and he should think that he needs a group.

"for there is no lone judge aside from the One [God]": The Holy One, blessed be He, who is alone (unique) in His world.

And do not say, "Accept my opinion": Also when you take a group to judge the legal case and they disagree with you, do not say, "I am the expert and they are not experts. [Hence] they should accept my opinion and nullify their opinions in my [favor]. As if it were not for my humility, I would have judged the case alone; [so] now too, [decide according to] my argument." As you should not think this.

"And don't say": to your colleagues that disagree with him, "Accept my opinion, since I am an expert and I could have judged without your association."

for they are permitted and not you: If your colleagues (rise early) [agree] with your opinion, it is upon them to accept your words. But, if not, you are not permitted to force them about this.

"for they are permitted and not you": Given that you have joined them to you, it is fitting that he should decide according to the majority.