When I speak of "abandoning conventional wisdom" in MCTB, you will note that it is not in relation to the powers nor in relationship to anything related to a scientific materialist worldview, but instead what I had in mind was numerous people who I witnessed believing things that are basically not obviously helpful when instead their "old" beliefs might have suited various situations much more nicely.
I actually think that, for certain pursuits, scientific materialism is a fine and functional worldview.
For other pursuits more unusual points of view may be useful.
The crux for you (and some other posters) in answering the question of "does it matter?" is pragmatics. Whatever works. What I am continuing to appreciate about what makes the DhO a special place is that it really fulfils what "pragmatic dharma" means. Anything goes, as long as it works. Stuff that works (like mahasi noting) gets a lot of air time, but other approaches that aren't so effective don't get much attention. And science doesn't get that much focus here. There is a science sub category but not a lot of posts (though I suspect it might not have been around for that long). This doesn't mean that forum members tend to reject a scientific worldview. Instead, it probably more reflects that scientific approaches to spirituality (at least right now) don't have a whole lot of offer in terms of helping people on the path (though I suspect that will change in time).
Maybe I might have been better off titled this post rejection of science/materialism/rationalism rather conventional wisdom. But then again, maybe not. You appear to be saying it is ok to reject conventional wisdom:
a. In situations where conventional wisdom doesn't apply well (in your opinion)
b. When it leads to harmful consequences
A few issues here. As raised in the earlier posts, then if you are deluded you don't know you are deluded, and it seems problematic to say you can throw away the rule book whenever you have decided the rulebook doesn't apply.
And as befitting someone who takes a scientific materialist worldview, I don't see situations where we would want discard that worldview when we want to understand what is happening in our minds and in the world. Why not apply a scientific materialist worldview to spirituality? It has been remarkably successful in other fields, and as a product of human brains I don't see spirituality as being any different. That worldview would hold that the behaviour of social groups is a result of neuronal activity in brains rather than the force of some magical spiritual energy that "inhabits" brains, as dualists might believe. Yes it is true that quantum physics is not an useful mode of explanation for the behaviour of individuals, which is due to the level of explanation required, but together the different levels of explanation can fit together in a coherent framework. We don't need to postulate a separate new level of explanation of some magical realm or dimension filled with qi/energy, ghosts, angels, and fairies. And I am not suggesting that folk psychological constructs raised by Johnathon Marks such as conscientiousness, heedfulness, duty, self-cultivation and hard work aren't useful as descriptions of behaviour, but that we have a framework in which such constructs can be understood in that coherent framework.
To whom are you referring when you say that some reject conventional wisdom? You can name names: it will not only be ok here, as this place is about real people having real conversations about real things, hopefully, but will make this so much more concrete and workable, where as now it lives in the world of vague innuendo, which lacks basic efficiency and efficacy.
I personally reject the notion that I, for one, reject conventional wisdom in any obvious context where conventional wisdom applies well and would truly enjoy debating any such notion, but perhaps I am missing something here and would gain wisdom from having that view challenged.
Do you have a specific example of someone from this small but unnamed cabal of wisdom-rejectors who have run into real trouble due to their mis-applied frameworks?
I saw a recent post from "hermetically sealed" about demonic possession. And it made me very thankful that most of us live in a world where a scientific worldview makes us think such as things are ridiculous.
In other parts of the world people aren't so lucky:
In April 2008, in Kinshasa, the police arrested 14 suspected victims (of penis snatching) and sorcerers accused of using black magic or witchcraft to steal (make disappear) or shrink men's penises to extort cash for cure, amid a wave of panic.[75] Arrests were made in an effort to avoid bloodshed seen in Ghana a decade ago, when 12 alleged penis snatchers were beaten to death by mobs.[76] While it is easy for modern people to dismiss such reports, Uchenna Okeja argues that a belief system in which such magical practices are deemed possible offer many benefits to Africans who hold them. For example, the belief that a sorcerer has "stolen" a man's penis functions as an anxiety-reduction mechanism for men suffering from impotence while simultaneously providing an explanation that is consistent with African cultural beliefs rather than appealing to Western scientific notions that are tainted by the history of colonialism (at least for many Africans).[77]
<https://en.wikipedia.org/wiki/Witchcraft#Africa>
In these cases, those involved are actually following conventional wisdom of their society, and as argued by the person cited the magical beliefs can "work". But would you rather live in the world where we have rational scientific accounts of magic and witchcraft, or one in which in you can decide those certain circumstances where those rational accounts don't apply?
While these forums don't lend themselves to detailed case studies to try and meet your challenge of where irrational beliefs lead people to problems, I can raise the case study of the poster named Daniel M. Ingram as a particular concrete example, despite the get out clause "in any obvious context where conventional applies well". As I have argued above, to understand the causes of events and how the world works, then conventional wisdom (AKA a scientific worldview) seems to me useful pretty much all the time.
From what I have read, I think it is fair to say you have got really caught up in spirituality (along with Magick, powers and the like) and are more than a bit fascinated with it.
http://www.dharmaoverground.org/web/guest/discussion/-/message_boards/message/4309442
You describe putting yourself in a state where you read everything you can about these experiences, really really want to have these experiences, and try really hard to get them, meditate really hard (and put yourself your mind in a very unusual state) and then you have these experiences. Regarding these experiences: "Sometimes I have felt them, sometimes heard them, sometimes seen them as clearly as I could see anything else" . An example might be "
being able to put my "ghost-hand" through a wall with all awareness and sensation perception then embodied in that rather than my usual body" or "send fantastic blasts of bright light that looked like the blasts from the backpacks of Ghost Busters down through the floor and up into candles to make them move". Your account seems exactly like a case of saying "well, it seemed real to me, ergo, it is real" - the lines are different lengths = I was able to control light with my mind. Needless to say, the scientific worldview/conventional wisdom account of these experiences is that you were hallucinating - "the absence of a stimulus which has qualities of real perception". That you can't control light with your mind is as common sense to me that "If put a glass on a table, I can expect it to be there in the next five minutes."
In answer to the question of whether this has led you to real trouble, while I can't say for sure, the answer is probably not. I would guess you have spent a lot of time exploring these phenomena where perhaps your talents might have been better spent elsewhere - you tend to read a lot of warnings out there by wise Buddhists not to deliberately cultivate powers as you can side tracked. But on the positive side, interpretation of strange experiences as evidence that you have gained special powers could be very encouraging, allaying doubt, and reaffirming your belief in the practice, which might give you a helpful boost along the difficult spiritual path, ultimately benefiting your practice.
So if it doesn't harm anyone, doesn't lead you to mess up your life, and can actually help you to become a happier person, then surely it is ok to reject conventional wisdom and scientific accounts of phenomena? It depends on your goals. Personally I am just as (if not more) interested in the "how it works" question than "if it works" (and getting results) question. And as I said, while science right now isn't that much practical help for the spiritual path, I think that will change in time, and all the irrational belief systems surrounding spirituality will interfere with that progress.
RE: actualism, while its popularity was presumably down to a number of factors, and the practices must "work" to a certain extent, I would say it was primarily down to a deep seated desire in humans for "freedom", for happiness, for the end of suffering. Despite Richard being a somewhat dubious character with signs of what normally might be classified as mental illness, people believed in what he was saying because they wanted to.