I can’t count the number of times that I’ve said something like, “I accept evolution because it’s the scientific consensus” and gotten the response, “Gotcha! Argument from Authority Fallacy!”
Let’s take a look at this fallacy and see where it applies and where it doesn’t.
Suppose I said, “Dr. Jones is smarter than both of us put together and he agrees with me, so I’m right!” This statement could fail due to the Argument from Authority Fallacy for two reasons: (1) we haven’t established that Dr. Jones’ expertise is relevant to the question at hand, and (2) even if Dr. Jones is an expert on the subject, that he agrees with my position doesn’t make me right—at best, it would make me justified in holding my position.
Chastised at my poor argument, I go back and rework it. Now I’m careful to first establish Dr. Jones’ relevant expertise and I modified my claim this way: “Dr. Jones, an established authority, agrees with me, so therefore my position is well justified.” This is better, but my statement could still fail due to this Fallacy. What if Dr. Jones is a maverick in his field? He could be a cosmologist still holding on to the Steady State model of the universe now that the Big Bang model is the overwhelming consensus. Conversely, imagine that it’s the 1930s and he is arguing for an expanding universe when that was the minority position. Either position makes Dr. Jones a maverick, and the layman (as an outsider) has no grounds from which to conclude that this minority position is the best approximation.
The Argument from Authority is not a fallacy when the person indicated (1) is an expert in the field and (2) is arguing for the consensus. Of course, that doesn’t necessarily make you right, but being in line with the relevant consensus is the best that we can hope for.
I’m amazed when I hear people reject evolution who aren’t biologists. I can imagine browsing biology textbooks and concluding that evolution is a remarkable claim. I could even imagine thinking that the evidence isn’t there (though the fact that I’ve only dipped my toe into the water would scream out as the explanation for this). What I can’t imagine is concluding, based in my “research,” that the theory of evolution is flawed. I mean—on what grounds could I possibly make this statement? On what grounds could I reject the consensus of the people who actually understand this stuff? The people who actually have the doctorate degrees and who actually do the work on a daily basis?
And yet I hear people justifying this step all the time.
Let’s move on to another topic, the question of consensus. After many discussions that have forced me to carefully think my position, let me offer my views on consensus from different fields. Note that this is the view of a layman—someone who is an outsider to these fields.

• Scientific consensus: I always accept this.
• Historical consensus: I always accept this.
• Consensus of religious scholars about their own religion: I always accept their statements of what their beliefs are. For example, when the consensus of Catholic scholars says that within the Catholic church the eucharist (the communion wafer) is believed to transubstantiate into the body of Christ, I accept that.

But don’t accept everything. I draw the line at supernatural claims, whether by scholars or believers, and whether the consensus or not. I will consider evidence for these claims, but so far I have always rejected them.  If I were to accept these claims, that would probably be based either the scientific or historical consensus.
Supernatural claims are in a very different category than scientific or historical claims.  For more, see my post Map of World Religions.
Photo credit: Wikimedia
Related posts:

• See all the definitions in the Cross Examined Glossary.
• Map of World Religions

Related links:

• “Argument from Authority,” Wikipedia.
• “Argumentum ad verecundiam,” Iron Chariots Wiki.