1. There are Mitzius questions (e.g. Who was R’ Yehoshua Ben Korcha and when did he live? How old was Yitzchak at the tiem of the Akeida?) Which obviously have a right answer and wrong answers
2. We see from this rishonim themselves. Look at some of the Rashbams in Bava Basra and see how he refers to some counter opinions (e.g. HEVEL, etc)
3. NEVERTHELESS, we are not able to take sides. WE can’t say PLONI RISHON was wrong. We can observe from the nature of the machlokes that one is wrong and one is right, we can’t choose, and we should do our best to understand both sides and how they got to their opinion