I will give just one example, and this whole page should only be read by those interested in my opinion.
The multimillionaire celebrity osteopath, Dr. Mercola (though he is not a scientist), has said and taught plenty of good things. I appreciate, for example, his encouragement to people to stop eating so much ultra-processed pre-made foods, stop seeking a pill for every problem, stop being sedentary, and stop eating so often. I recognize these good teachings and do not dispute them. Mercola himself is perhaps perfectly well meaning.
But I would caution my readers to steer clear of his controversial claims. As should be the case with anyone, when he presents (and cites) strong evidence for his claims, then, of course, we must regard that evidence seriously (or at least, we must regard it in proportion to the weight of the argument he presents for it). But I do not think that Mercola’s views should themselves ever be relied upon as an authority in seeking to demonstrate that some claim is legitimately scientific. For Dr. Mercola also regularly promotes new age teachings and pseudoscience. See this video, for example, promoted on his website, wherein it is argued that all disease is from emotion; in particular, “negative emotional molecules” that can only be purged from the body through special knowledge (pay up and maybe you’ll be given that knowledge!), after which we can finally engage in “manifestation” and “create our own reality” and get the “universe to step towards us.” I hope I do not need to waste any time arguing the obvious here: this is patently absurd new age teaching. While it doesn’t appear Mercola himself made the video, I do not find it plausible that his own website, which bears his own name, has hosted that video for 5+ years without Mercola’s own endorsement and approval.
Here, Mercola advocates for “grounding,” a frequently promoted tenet of new age pseudoscience (and this “grounding” quackery relies upon principles I do sufficiently understand to say, from my own knowledge, is utter fake science). I’ve never watched a video from Mercola before this; I simply did a YouTube search for his name — that was the first video that popped up, and it contains clearly new age teachings. I can only imagine how much new age material I’d likely stumble upon if I watched/read more of his teachings. But I needn’t list here all of the pseudoscience he has been promoting over many years and getting rich off of; that is all well-documented and easy to find with a quick online search. Even for those who feel that “Big Pharma” is the devil incarnate and the FDA is its prophet, it should still be easy for such people to see how deeply problematic Dr. Mercola’s teachings are. I would kindly ask that, if such people protest the categorical denunciation of naturopathy, that they do not fall into the same prejudice by categorically denouncing something just because the FDA said it. Instead, simply ignore all prejudice, and analyze individual claims in accordance with the evidence for them. In the course of seeking that evidence, be sure to spend equal time reading the best sources on both sides of the issue. Don’t just spend your time looking for proof of what you want to believe. And remember that finding a study simply looking into an issue isn’t proof of anything. You need to look for conclusions that have been demonstrated across multiple trustworthy studies. As I mentioned, these studies should preferably be in peer reviewed journals (so don’t forget to see what the peers have said about the study!), double-blinded, and placebo-controlled. As you can see, picking through abstracts here and there, and surgically extracting only what seems to bolster your view, won’t suffice. Nor will even a careful undertaking of this approach I here advise guarantee that a non-expert will arrive at the truth (more on that below).
Finally, remember that I only mentioned Mercola as one example. There are countless doctors and scientists like him. In striving to ascertain whether a given doctor or scientist should be dealt with in such a way as to treat his or her views themselves as authoritative statements, it is essential to research what other things this person has already said. This is not an ad hominem attack based approach; it is, rather, seeking to understand the nature of a tree by its fruits. Indeed, we should ignore the ad-hominem attacks of the hit pieces inevitably written against those who contradict the mainstream, for these fallacious attacks cite the moral failings of a person to try and persuade rejecting the intellectual efforts of that person. But one cannot, on the other hand, ignore the relevance of what a given doctor or scientist has already promoted as being “scientific” in striving to determine whether what he now promotes is legitimately scientific. If a given doctor or scientist has already defended or promoted things we know are new age or pseudoscientific (see section 2.2.3 in this Vatican document for a list of just a few examples); acupuncture, homeopathy, craniosacral therapy, crystal healing, phrenology, rolfing, vitalism, magnetic therapy, vitalism, grounding, Qi, energy medicine, etc., then we can at least safely conclude that this doctor or scientist is operating under the influence of some premises that themselves are flawed and have likely generated who knows how many other errors in his or her medical or scientific opinions.
I must reiterate that what I am advocating for here is not an ad hominem based approach; I am simply acknowledging the fact that lacking what it takes to judge the cortex directly requires that we instead judge the fruits. For example: Are you a biochemist? If not, then it would be better not to lie to yourself and pretend that you have what it takes to master the subtleties of biochemistry and decide which biochemist (in a debate amongst them) is correct, no matter how many hours you spend doing Google searches. Nor should you pretend that you have what it takes to confidently decide — among a batch of biochemical studies on a given question — which study is the one that comes to the strongest conclusions. Expertise is not needed merely for generating the studies; it is also needed for properly understanding the studies, comparing and contrasting them, and using them to come to actionable conclusions. So, instead, what you are stuck with is the need to ascertain for yourself which biochemists are most worthy of credence. And since, as a matter of epistemology (philosophy of knowing), we are always by definition stuck beginning with the premises we already have in deducing further knowledge, the only practical way you can decide which experts are worthy of credence is by comparing what they have already said/done to the knowledge you yourself already have. To this end, one of your most powerful tools is going to be seeing if a given “authority” has already promoted things that you should know, from your Faith or your Reason, is new age and/or pseudoscientific.
One more quick point. I am not advocating for a blind “trust the experts” attitude. First: When a given scientific question can nevertheless legitimately be examined directly with Reason even by one who is not trained in the field, then we needn’t feel any obligation to “side with the scientific consensus.” The question of evolution is a prime example. (See pages 526-532 in The Crown of Sanctity). Second: Whenever our Faith contradicts what any scientist says, then obviously it is the Faith that must always be trusted no matter how “authoritative” the scientist and no matter how seemingly strong the “consensus” (as, for example, is the case with scientists who argue for abortion, euthanasia, transgenderism/homosexuality, contraception, embryonic stem cell research, non-human personhood, materialism, random evolution, etc.).