The author is likely looking at the Sperry/Gazzaniga experiments, and... getting them wrong. The insight was that the left brain fills gaps in information, and yes, it is confabulating. If your right and your left brain lobe happen to be severed.
Our reasoning is far from unknowable in a non-severed brain. Yes, people are sometimes lying, and yes, "actions speak louder than words", but that doesn't mean you should blanket-dismiss explanations.
Your comment would be fine without the first bit.
I've definitely experienced people's stated beliefs continually disagreeing with their actions, and their producing a font of rationalizations when I asked them about it, until I was forced to conclude they were lying to me only because they'd first lied to themselves. Or confabulated, if you prefer.
And I think it's important to understand that this can happen & that one's self can do it too. Which is, yanno, a meaning.
https://en.wikipedia.org/wiki/Hemispatial_neglect
When we have brain damage that causes us to neglect one side, we don't notice that we're neglecting one side. If it's pointed out, we unintentionally give specious reasoning as to why it happened.
This is common knowledge, not based on a particular study, but many of them.
edit:
> Our reasoning is far from unknowable in a non-severed brain.
Are you saying this based on something, or is it just a personal belief? If there's anything we know about introspection, it's that it is untrustworthy.
And in both cases - severed lobes, and hemispatial neglect - serious trauma needs to be present to observe this effect.
I do think the changed title here on HN is doing the subject much more justice than the attention-grabbing attempts of the article.
It's "at the very least" worth considering: What does it mean that under specific circumstances we can be so sure of ourselves about such basic stuff and so totally wrong at the same time?
It might not be a strong inference from split-brain phenomena, but it'd be a shame to /not/ wonder about whether and how much such confabulatory mechanisms are at play in normal functioning brains, then
Some people confabulate, memory is not perfect, people with severe brain injuries visibly confabulate, so all explanatory power is meaningless and we should never trust it.
Never mind that some specific lesions to the brain actually provide explanations for how we create narratives and confabulate. Those explanations are equally illusory...