However, the Sforno suggests that Yehuda was saying "for what gain of revenge", and he elaborates on Yehuda's line of reasoning with the brothers by noting that there are two purposes one can gain from revenge. The first benefit from revenge is the feeling of satisfaction, while the second is to instill fear in others as a deterrent. Yehuda said to his brothers that neither purpose of revenge would be served by killing Yosef- there would be no satisfaction because ultimately it will lead to guilt and remorse, and there will be no deterrence since the entire episode is being kept a secret.
It seems that according to the Sforno the driving force behind the brothers attempted murder of Yosef was the desire for revenge and Yehuda was able to stop them by reasoning that this was not the best way to exact revenge. However the Sforno himself just a few verses earlier goes to great lengths questioning how it can be that the the holy tribes could want to kill their brother, so inappropriate for such lofty souls. He answers by suggesting that the brothers considered Yosef to be a rodef (pursuer who wishes to kill someone), and they were therefore obligated to kill him first.
How can we understand Yehuda's argument to his brothers if in fact Yosef has the status of a rodef? Why would they change their minds merely because this was not the best way to get their revenge, if they already deemed Yosef a rodef, if he was a threat to their lives?! Rabbi Henoch Leibowitz suggested that even though the brothers' reasoning for killing Yosef was indeed based on their misconception that Yosef was a rodef, they had only reached this conclusion because of deep desire to take revenge against him.
Yehuda understood this, and instead of arguing with their line of reasoning, he "cut to the chase" and argued with them that their subconscious biased wish will not be fulfilled by killing Yosef.
It is fascinating to note, that although the shvatim did not realize what had lead them to the false conclusion of classifying Yosef as a rodef, once they heard Yehuda's suggestion which cut to the core of their feeling, they immediately understood and agreed with him. In our own lives sometimes we come across a person who makes seemingly illogical arguments.
Perhaps instead of dismissing the arguments as flawed and/or debating the finer details, it would be worthwhile to analyze what is driving this person to reach this conclusion which is clouding his judgement and analytical skills. In this way we can hopefully address the true issue at play, and have more chance in reaching out to them and being mashpia.
May we merit to reach the truth within ourselves and help others achieve clarity in their lives as well.