Everybody promotes these sorts of hypotheses to beliefs because it's not a conscious decision you are aware of. It's not about being clumsy or apt. You don't have much control over it.
It does not matter, that there may be a tendency towards bad thinking: what matters is the possibility of proper thinking and the training towards it (becoming more and more proficient at it and practicing it constantly, having it as your natural state; in automation, implementing it in the process).
What you control is the intentional revision of thought.
(I am acquainted with earlier studies about the corpus callosum but I do not know why you would mention that, what it would prove: maybe you could be clearer? I do not see how it could affect the notion of critical thinking.)
I've explained it the best i can in the other comment. But you keep making the mistake that this is just a culprit of 'bad thinking' or 'intentional revision of thought' and while i'm not saying those things don't exist, It's not.
Not only are the rationalizations i'm talking about and which some of these papers allude to not intentional, they often happen without your conscious awareness.
On my having come with percussions at the strings meeting see the other reply.
I want to check the papers you proposed as soon as I will have the time: I find it difficult to believe that the conscious cannot intercept those "changes of mind" and correct them.
But please note: you are writing «Not only are ... not intentional»... Immature thought needs not to be intentional at all: it is largely spontaneous thought. But whether part of an intentional process ("let us ponder towards some goal"), or whether part of the subterranean functions, when it becomes visible (or «intercepted» as I wrote above), the trained mind looks at it with diffidence and asks questions about its foundations - intentionally, in the conscious, as a learnt process.