If a majority of experts agree on an issue, a rationalist should be prepared to defer to their judgment. It is reasonable to expect that the experts have superior knowledge and have considered many more arguments than a lay person would be able to. However, if experts are split into camps that reject each other's arguments, then it is rational to take their expert rejections into account. This is the case even among experts that support the same conclusion.
If 2/3's of experts support proposition G , 1/3 because of reason A while rejecting B, and 1/3 because of reason B while rejecting A, and the remaining 1/3 reject both A and B; then the majority Reject A, and the majority Reject B. G should not be treated as a reasonable majority view.
This should be clear if A is the koran and B is the bible.
Positions that fundamentally disagree don't combine in dependent aspects on which they agree. On the contrary, If people offer lots of different contradictory reasons for a conclusion (even if each individual has consistent beliefs) it is a sign that they are rationalizing their position.
An exception to this is if experts agree on something for the same proximal reasons. If pharmacists were split into camps that disagreed on what atoms fundamentally were, but agreed on how chemistry and biology worked, then we could add those camps together as authorities on what the effect of a drug would be.
If we're going to add up expert views, we need to add up what experts consider important about a question and agree on, not individual features of their conclusions.
Some differing reasons can be additive: Evolution has support from many fields. We can add the analysis of all these experts together because the paleontologists do not generally dispute the arguments of geneticists.
Different people might justify vegetarianism by citing the suffering of animals, health benefits, environmental impacts, or purely spiritual concerns. As long as there isn't a camp of vegetarians that claim it does not have e.g. redeeming health benefits, we can more or less add all those opinions together.
We shouldn't add up two experts if they would consider each other's arguments irrational. That's ignoring their expertise.
I remember (somewhat, details may be a bit foggy) in Richard Feynman's biography of sorts, he tells a story about a time when he served on a committee to recommend new science books for (I think) several grade levels like 6-12. He first wryly notes that he was the only member of the committee to read all of the candidate texts from several publishers in each grade level in their entirety. He ended up recommending science books by a publisher that was not in favor with the rest of the committee, and their principal reason for liking another publisher's books was because two-hundred engineers had participated in a review of some of the same books and their votes pointed to this other recommendation.
So the committee asks him to justify his different recommendation with an appeal to authority - "surely you are not smarter than 200 engineers!". He says something along the lines of no I don't claim to be smarter than the sum of 200 engineers, but thats not what you have here. I am smarter than the average of 200 engineers.
Now clearly, we can't all be experts in everything and have to yield to expert consensus as a matter of practicality - but it should never be assumed to settle anything - apart of course from cases where its a majority of people testing hypothesis and models and finding them in agreement with observations. That has real lasting value - even if the model is later found to be flawed its usually still "good enough" for most observations (e.g. Newton's physics).