This is lightly edited from 2013 emails I wrote to FI list. I was talking about Peikoff's Objective Communication audio lectures.
Ayn Rand (AR) advocates fallibilism. In a serious, substantive way, in print.
So far from Leonard Peikoff, I've heard a lot of stuff that sounds potentially incompatible with fallibilism, such as advocating certainty, with no effort made to explain how he means something compatible with fallibilism.
I've heard him dismiss some fallibilist arguments, which are true, as ridiculously stupid, without argument.
I've heard him define skepticism as a denial that certainty is possible. Then talk about it as a denial that knowledge is possible. The unstated and unargued premise is that knowledge requires certainty (he didn't mention Justified True Belief, but is that what he has in mind?). How that premise is compatible with fallibilism, he has not informed me.
I have not heard him advocate fallibilism like Rand has.
In addition to certainty, Peikoff has said perfection is possible. He clarified that he meant contextual perfection. Perhaps he also thinks that only contextual certainty is possible. I think this is a misuse of words. He hasn't explained why it isn't. And he keeps talking about "certainty" without any mention of "contextual certainty". If he means something rather different than a typical infallibilist meaning, shouldn't he be clear about it?
Further, when he attacks skeptics for rejecting certainty, it's unclear that those skeptics are all rejecting "contextual certainty" (if that is what he actually means but doesn't say). There are skeptics who (correctly) refute non-contextual certainty (which is infallibilism). If a skeptic refutes non-contextual certainty, and an anti-skeptic like Peikoff advocates contextual certainty, then they haven't necessarily contradicted each other. Peikoff talks about these subjects but doesn't deal with points like this. But he doesn't just omit stuff; he seems to be contradicting points like this -- and therefore be mistaken -- and he fails to explain how he isn't mistaken.
Peikoff focusses his attacks on the worst kinds of skeptics and acts like he has criticized the entire category of all skepticism. He doesn't mention or discuss that there are different types of skeptics (e.g. rejecting all knowledge, or just rejecting non-contextual certainty. He seems to lump fallibilists in with skeptics, though I have no doubt he wouldn't want to lump AR in with skeptics, so his position isn't explained well.)
If you want to exclude people like myself and Karl Popper (and AR) from being skeptics, fine. But then you can't just define skepticism as rejecting certainty! Unless you add a bunch of clarifications and qualifications about what you mean, Popper absolutely does reject certainty! (As do I.) You'd also have to stop presenting it as skeptics and non-skeptics, only two categories, since Popper and Peikoff would be non-skeptics with major differences in views. (I don't normally present it as skeptics and non-skeptics, but Peikoff did.)
These comments above are from his Objective Communication lectures. Epistemology is not the primary topic, but he keeps talking about it. (He's also talked about induction and empiricism a number of times. That material is also problematic.)
I've never seen AR do it like Peikoff. Whenever she talks about these things I have a tiny fraction of the objections. But when it's Peikoff (or Binswanger or I think many other Objectivists) then I see lots of problems.
On another note, Peikoff's comments about how awful school is are worthwhile. They are directed especially at grad school and university. He talks about how much it trashed his mind (despite his best efforts not to let it do that), and how dangerous it is and hard to stay rational, and how much time and effort it took to recover.
In a way, it excuses his other mistakes. He actually read some stuff from a paper he wrote in grad school. He's improved a lot since then!! So that's great. One can respect how far he's come and perhaps sympathize a bit with some of his mistakes.
I for one have the advantage of avoiding a lot of the tortures Peikoff endured at school. It really helps. Yeah, sure, K-12 sucked but I never took it seriously after around 6th grade or maybe earlier. It's so much worse and harder if you take it seriously.
(But I fear he wouldn't appreciate this perspective much. I fear he'd say he's super awesome now and not making mistakes, and I'm wrong about epistemology -- but without wishing to debate it to a conclusion in a serious way, as I am willing to do. If he rejects the attitudes and role of a learner still making progress, then it becomes hard to sympathize with errors. If he also isn't open to answering criticisms, then it's even worse.)
How few philosophers Objectivists find to appreciate is one of the worrisome things that does apply to AR herself (I learned from AR, Popper, Goldratt and others. Peikoff doesn't seem to have gotten much value from people besides AR). Like it's a problem with Peikoff but also with AR. She was aware of Mises and Szasz. But she missed Popper, Burke, Godwin and Feynman, for example. Is there any excuse for that? Godwin is obscure but Szasz was aware of him! Mises was aware of Godwin too, but Mises read a translation and totally got the wrong idea. Szasz and Mises were also aware of Burke. I'm not sure how much Mises knew about Burke, but Szasz had a good understanding. Szasz also knew a lot about Popper, and had some familiarity with Feynman. So if Szasz can find all these philosophers, and learn from them, what is AR's excuse?
And of course I can and did find and study Godwin and others too. I sought out good philosophy with some success. It's not trivial to find, but it's worth the effort.
Peikoff's on-topic comments about Objective Communication continue to be good. No monumental breakthrough, but lots of solid points explained well.
Peikoff said certainty is conclusiveness.
If we figure he meant contextual conclusiveness (if he didn't, that's worse!), that's Popper-compatible. Popperians reach what they call "tentative" conclusions which means that they are the current conclusion but could need to be reevaluated if the context changes (e.g. something new is thought of).
But can something called "tentativity" really be what Peikoff has in mind for "certainty"? I don't think so. If you listen to how he talks about it, and his examples, they do not fit this interpretation of the definition. But he doesn't clarify the correct definition or the way to interpret this one.
No comments are made about how his definition is compatible with this other thing he doesn't mean, or what's wrong with this thing. He doesn't address it. I don't think he's thought of it.
Long story short, what's going on is Peikoff is mistaken about the topic so his comments come off confused from the perspective of someone who already understands what he's missing.
Peikoff is targeting his comments against ideas much worse than his own. He's defeating what he sees as his (awful, pathetic) rivals. But why hasn't he engaged with any better rivals?
I don't think it's pure ignorance. For one thing, that would not be excusable: he should have checked for the existence of some better ideas.
But also, Peikoff knows (and endorses) Binswanger, and Binswanger knows of Popper. Binswanger's attitude to Popper is a combination of extreme ignorance and extreme venom (with extras features such as misquoting Popper and then not caring or correcting it). Some other Objectivists also know of Popper but reject him without rational, well-informed arguments or an adequate understanding of his ideas.
I suppose I should look these issues up in OPAR. But he's supposed to be talking to an audience with merely some knowledge of Objectivism. So if you've read everything AR says about this, that ought to be (more than) enough. His comments weren't meant only for audiences that have read OPAR.