The role of decision-making

I have read in several places that if we advocate the position that the Torah is in an endless process of self-improvement, interpretation, and innovation, and that then the disagreement between commentators is necessary and positive and not a negative thing stemming from a historical accident, then it follows that the ruling of the law helps in making the law applicable and in forming certain practices, but it does not determine the truth of one opinion over another.
 
But are these things really necessary? Is it not possible to advocate the position that disagreement is necessary and positive, and at the same time think that the function of the decision is to reach the truest decision (in the eyes of the decider)?