Experts know more about their subject of expertise than you do. So, if you discover that you possess a view that contradicts the vast majority of experts, it’s more likely than not that they’re right and you’re wrong. In determining your own level of confidence on a matter, this is an important fact to keep on the table (and not brush it under a rug). This is not the case with an appeal to authority. Authorities can frequently be ignored because authorities are authorities for only some people, but not others, and their authority rests in consent, not empirical knowledge.
Expert consensus based in empirical knowledge and well established scientific theory must influence the thought of all rational people; it cannot be escaped or blown-off; it must be grappled with (again, if you are to be rational). Not so authority. The Pope, for instance, is an authority for Catholics only. If you have not already consented to being a member of the Catholic religious community, his opinions and pronouncements need not influence your own thinking. You might belong to a different religious community, or simply regard your own opinion on angels or ethics to be as good as anyone’s—including the Pope’s.
An appeal to authority thus entails circular reasoning (which is generally cautioned against as a logical fallacy): you have to already believe in the authority to accept the conclusions of the authority. But in critical thinking the conclusion is what is in doubt. Here’s an example of circular reasoning: “The Quran is free of error. I know this because the Quran says it is free of error.” Here’s another: “Buddhist meditation is beneficial. I know this because the Buddha declared it to be beneficial.”
Authority, by its very nature, sets boundaries around permissible thought and language surrounding certain topics; it tends to arrest full inquiry and lays down terms for the range of acceptable dialogue and questions among those who submit to it. At some point, to remain within a community under authority, you have to follow its tradition; its program; its direction.
Or you have to leave the movement.
Boundaries established by an authority may be considered pleasing, and not confining, by those who do submit to them. Followers of an authority might even describe their own opinions as exactly the same as the authority that they submit to (and so they’re not really submitting to anything; they agree). They might also conclude that they are wise to submit. Not confident in their own intelligence and thinking processes, they surmise that they need help in arriving at good conclusions, and submitting to an authority that they trust (for whatever reasons) is perceived as the safest route for them.
The authority obliges them.
A Marxist, for example, may like the way that Karl Marx writes about the alienation of labor and wouldn’t think of discussing it in any other way. There’s no inner conflict at all. She might regard Karl Marx’s way of writing about the alienation of human labor as the last and best word on the matter, and feel free to never have to think about the subject further. (“If it’s a good enough explanation for Karl Marx, it’s good enough for me!”) On matters economic and revolutionary, Karl Marx is her authority. She may even be in awe of Karl Marx, referring to him with unironic reverence and participating, with other local Marxists, in a cult of personality surrounding his image. Marx, for her, is an icon, and she gets angry when anyone questions his ideas or the enthusiasm for his ideas on the part of her fellow Marxists. And the leader of her group, which she also treats as an authority, affirms her in these attitudes.
Likewise, a woman may announce that she is pregnant solely on the authority of a guru’s ecstatic prophesying over her, and find herself free of any desire to visit a physician to confirm what she thinks she already knows. Her guru may not discourage her surrender of judgment to him.
But in your own analysis, you can ignore such arrestings of thought to belief, or weigh them lightly, and keep right on thinking and doubting.