Rational thought, yes. Critical reasoning, a little doubtful, especially these days. Oral traditions are so inefficient at transmitting multiple viewpoints, at collecting multiple viewpoints, at codifying multiple viewpoints, and eventually at balancing multiple viewpoints that human society desperately sought and successfully figured out written ones. For example, great orators with really bad messages could easily sway people down all kinds of wrong directions. I am yet to see a great writer who achieved anywhere near the same effect (without also being able to articulate the same message just as well orally).
For example, think of the first time you read a comment on HN which you impulsively disagreed with. If you gave it a second and a third chance, sometimes you come away with an alternate viewpoint, and sometimes you actually agree with the statement. That is the power of writing.
Now imagine what happened the last time you verbally disagreed with someone. Chances are, you soon branded them an idiot, and then slowly stopped talking to them. I would say a part of it was simply because the message was conveyed orally, with all kinds of meaning ascribed to intonations. And unlike reading a piece of text again carefully, its not as if you have a mental tape recorder you can use to replay the conversation. There is just too much distraction in oral communication.
Oral traditions are so inefficient at transmitting multiple viewpoints, at collecting multiple viewpoints, at codifying multiple viewpoints, and eventually at balancing multiple viewpoints
To these ends I agree that oral traditions wouldn't "scale up" quite as well as written ones - but we're talking about pretty small groups of people, so they're going to have less viewpoints on the whole and therefore less need of a system that helps them manage intellectual pluralism. And as a side note, I'd think you don't really need multiple viewpoints to engage in deductive reasoning, if we're counting that as critical reasoning.
great orators with really bad messages could easily sway people down all kinds of wrong directions
Massive lapses of critical reasoning also affect post-literate Western societies.
think of the first time you read a comment on HN which you impulsively disagreed with...
You can impulsively disagree with someone and subsequently change your mind without the need to write everything they said down. You probably do this every day in casual conversation - especially if you're a software engineer - I'd bet most programmers are no strangers to impulsive disagreement. So I think your blessing here is really self-reflection - not a writing system. I think self-reflection falls under critical reasoning.
Now imagine what happened the last time you verbally disagreed with someone...
When you say that oral discourse has "all kinds of meaning ascribed to intonations", you're making it sound like speech is sort of a richer, more complex style of interchange than something purely textual like an email. Like, a speech act can have all kinds of richness and ambiguity. So wouldn't it then require more critical reasoning to parse out a speech than an email?
For example, think of the first time you read a comment on HN which you impulsively disagreed with. If you gave it a second and a third chance, sometimes you come away with an alternate viewpoint, and sometimes you actually agree with the statement. That is the power of writing.
Now imagine what happened the last time you verbally disagreed with someone. Chances are, you soon branded them an idiot, and then slowly stopped talking to them. I would say a part of it was simply because the message was conveyed orally, with all kinds of meaning ascribed to intonations. And unlike reading a piece of text again carefully, its not as if you have a mental tape recorder you can use to replay the conversation. There is just too much distraction in oral communication.