As is well known, in halakhic rulings one cannot dispute rulings that were decided in earlier periods. For example, Amoraim cannot dispute Tannaim, and medieval authorities (Rishonim) cannot dispute Amoraim. Many of the questions raised in the Talmud are based on this rule, when an objection is raised against an Amora from a Mishnah or a baraita.

There are two sides to this:

The earlier generations were greater in wisdom, and therefore it is clear that if later scholars see something that appears to them to be a mistake, they understand that they are certainly the ones who are mistaken, and that they must become wiser and penetrate the full intent of the earlier authorities (Kovetz Shiurim, part 1, Bava Batra, sec. 733, in the name of Rabbi Chaim; Kovetz Iggerot of the Chazon Ish, part 2, letter 24—cited in Orchot Ish, Jerusalem 1989, pp. 186-187; and more).

B. At the end of each period, the Jewish people accepted upon themselves the rulings of the sages of the previous period: at the end of the period of the Tannaim—the sealing of the Mishnah; at the end of the Amoraim—the sealing of the Talmud. And it is impossible to dispute that decision (Kesef Mishneh on Rebels 2:1—cited in Kovetz Shiurim, part 2, booklet Divrei Soferim, sec. 2, subsec. 5; and more).

In standard halakhic discussions, usually there is no practical difference between these two approaches, but in non-halakhic matters, and in some additional cases, there is a practical difference between the above approaches.

A. Why are they wiser? How do you know this secret?
B. The Talmud is the last thing that was accepted by the whole Jewish people. Anyone who came afterward was not accepted.

A. See tractate Sabbath 112, Eruvin 53. (Though there is also evidence to the contrary.)
B. At first I thought you meant the earlier generations in your remarks. But now I understand that you mean specifically the period of the medieval authorities (Rishonim).

“…And I saw that if we were to say that we would decide between the halakhic decisors on the basis of Talmudic arguments and proofs, then Tosafot, the novellae of Nachmanides, Rashba, and Ran of blessed memory are full of arguments and proofs for every one of the views; and who is it whose heart would dare approach to add arguments and proofs!? And who is it whose heart would embolden him to put his head among the mountains, the mountains of God, to decide between them on the basis of arguments and proofs, to overturn what they have selected, or to decide what they did not decide!? For because of our many sins, the bed of our intellect is too short to understand their words, all the more so to outsmart them.” (In the introduction to Beit Yosef on the Tur, Orach Chayim)
However, one should also look at the Maharshal, who wrote the opposite.
And even though this is not the accepted approach, there were great sages of Israel who disagreed with the rulings of earlier generations, such as the Vilna Gaon and the Rogatchover (Rabbi Yosef Rozin of Rogatchov).