You wrote that "it's not just about believing that you could be mistaken about things - it's also about considering the ways in which another person's view of the same issue might be similar to or different from yours, and how and why. Moreover, some differences may or may not matter in different contexts."
Actually, that's a good point, but I don't think the failure to see where the other person might be coming from marks one as a cultist. This is a problem that is common to practically everyone who feels strongly about a particular point of view, yours and mine included.
You write, "Error can be conceived of in a variety of ways, but if one takes the Popperian conception, which is not so different from that espoused by certain schools of Critical Realism and Absolute Idealism, error is only significant to the degree that it detracts from a solution. One doesn't need the absolute truth (if such a thing exists) to agree with the claim that some ideas are better than others when applied as solutions to certain problems."
Here I think you misunderstand what Objectivism means by "the absolute truth." (Could this be a failure to see where your Objectivist opponents might be coming from? ;-)) If one idea is a better solution than another, wouldn't you say that its ~true~ (absolutely true) that one idea is a better solution than another? The modifer "absolute" in this context is redundant, as it serves only to distinguish this view of truth from a relativistic one ("true for you" but not "true for me"). If something is true, it is true ~for anyone~, because an idea's truth refers simply to its correspondence with reality, irrespective of whoever happens to believe it or disbelieve it.
You continue, "From this perspective, error and infallibility do not become as important as solutions that work! And when looking for solutions that work, there might be a variety of similar and dissimilar perspectives that are deserving of consideration. Focusing on infallibility often blinds one to that possibility."
I don't think there's any contradiction here. Either a particular solution works or it doesn't; if it works, then the idea that it works is true - absolutely, 100% true.
You ask, "What's the difference between someone who is 99% certain and who is a 100% certain?"
Oh I see what you're getting at. You're saying that it doesn't make any practical difference whether someone is only 99% certain that something works and therefore cannot claim to ~know~ that it works and someone who is 100% certain and therefore ~can~ claim to know it, for in both cases, they will recommend the same action. Okay, fair enough. If I understand you then, you're saying that this concern with absolute certainty is overblown, because it doesn't make any practical difference in cases like the above. So, in a murder trial, for example, if I'm 99% certain that the defendant is guilty, I'll vote to convict him just the same as if I'm 100% certain, because in both cases, I'm convinced beyond a reasonable doubt.
You continue, "What's the difference between a physicist who believes that God created the world and one that doesn't?"
Right; I see your point: Ignorance or falsehood in one area does not necessarily affect one's judgment in an altogether different area. I don't think that Objectivism would disagree with this, although if your epistemology is irrational in one area, it could conceivably have an impact on other areas as well.
You write, "What's the difference between a man who believes that certain forms of sex are depraved and other forms aren't? In some contexts, such differences do not matter. But cultists who need conformity will make these differences matter in many contexts."
Perhaps, but where does the philosophy of Objectivism imply this kind of behavior?
I wrote, "What is characteristic of a dogmatist or true believer is not that he claims to be certain, but ~how~ he claims to be certain. If he adopts an idea thoughtlessly and carelessly and clings to it doggedly in the face of evidence to the contrary - if he doesn't consider it important to validate his beliefs - if he believes something only because it feels good or because his significant others agree with it - then he is a dogmatist irrespective of the fact that his ideas may be true. What characterizes a cultish mentality is not so much what he believes as why he believes it. If he accepts an idea on faith or on the basis of some similarly non-rational motive, then he is a true believer. In short, what is characteristic of a true believer is that he lacks both intellectual independence and a respect for evidential support and rational justification."
You reply, "Again, the key is not just 'contradictory evidence' but 'alternate perspectives' and the salience, coherence and truthfulness of these perspectives. Sometimes, the believer who searches for the one true way blinds himself to the fact that there are often many ways with different benefits and costs."
Granted, there are often many ways with different benefits and costs, but here you are talking about something different than philosophical truth, aren't you? You see, if you say categorically that "there are often many ways with different benefits and costs," you're claiming that this is absolutely true, and that anyone who denies it is deviating from "the truth." You're invoking a form of absolute truth in putting forth your position. In any case, Objectivists wouldn't deny that there are often many different ways to do something, all with different benefits and costs.
I wrote, "Indeed, one of the reasons people are attracted to cults is that they lack a sense of certainty and confidence in their own judgment, and are therefore prone to let others do their thinking for them. Objectivism, properly understood, serves as a protection against this kind of intellectual and moral hazard."
You reply, "Again, only if one is seduced by the kind of truth that excludes other possibilities. Of course, truth is a contextual thing, but my point is that the"my way or the highway mentality" that Objectivists foster in the land of ideas is inherently cultish."
I don't think that truth is contextual. I'm not even sure what that means. If an idea is true, then it correspond to reality. Insofar as reality is what it is irrespective of context, an idea's correspondence to it is what it is irrespective of context. Truth does exclude other possibilities, because there is only one reality. The only possible alternative to the truth is falsehood; either an idea is true or it is false; there is no third alternative.
You write, "And I think that this kind of thinking is required in the battle between philosophical ideologies that do not lend themselves to efficient testing and whose truth value partly depends on the agreement of others."
But Objectivism rejects the idea that the truth value of an idea depends on the agreement of others, which is a form of collective subjectivism and, in Objectivist lingo, implies the primacy of consciousness. Furthermore, don't you see that you yourself are putting forward a philosophical ideology of sorts - an ideology that is not itself subject to the kind of "efficient testing" that you presumably have in mind. Yet you are quite willing to accept your own views as true and the views of those who disagree with you as false.
You write, "My primary point is that many perspectives are compatible with the truth as we currently know it and that knowing what is wrong is far easier than knowing what is right. However, cultists prefer to have it the other way round."
Many perspectives are compatible with the truth? Not if we are talking about the same object of belief. If you believe X and I believe non-X, at least one of us is mistaken, because two mutually exclusive ideas cannot both be true. You say that knowing what is wrong is far easier than knowing what is right. I'm not sure I follow you. Do you mean something like the following: A claim is made that cell phones cause brain cancer and that view is discredited. We discover that it's wrong, but we don't yet know what's right, i.e., what does cause brain cancer? I agree that it may be easier to discredit one idea than it is to validate another. But there's an obvious sense in which by discrediting one idea, we ~are~ validating another. Insofar as it is false that cell phones cause brain cancer, it is true that they do not cause brain cancer. In that sense, knowledge of what is false ~presupposes~ knowledge of what is true.