It looks like I didn't explain myself well. I thank several people 
who wrote, both offline and on Avodah, and I'd like now to clarify my 
points.

I never meant to reject the idea (based, I believe, on Rambam in 
Moreh Nevuchim 1:2) that prior to eating from the tree, Adam and 
Chava based their decisions on emes/sheker, and that after eating, 
based on right/wrong.

But there is a great middle area between those extremes. Perhaps I am 
misunderstanding what people mean by "emes/sheker", but I understand 
it to refer to objective fact, leaving no room for opinions or 
emotions.

For example, Chava observed that the fruit of the tree was "tov 
l'maachal". I will concede that this might refer to the objective 
fact of it being edible. But it seems to me more likely that she was 
making a value judgment, that it was not only an edible food, but 
that it was a *good* food, i.e., better than some other foods. This 
is clearly how the Torah uses the word "tov" in reference to the gold 
of Chavilah (2:13), to describe it as above-average in quality.

What was life like, for people who did have bechirah chafshis, but 
did not yet understand right and wrong? I imagine that they might 
choose, for example, between two equally healthy fruits, but which 
had different tastes. Or perhaps they'd choose between fruit with 
different nutritional strengths. They had emotions, and desires, and 
the ability to choose from among them.

Could they have desired an unhealthy fruit? I don't know. Such an act 
would have been "wrong", but they did not yet understand that 
concept. Might they have rejected it as being "sheker"? Maybe, maybe 
not. Sheker is a reason not to use a southbound road to reach a 
northern destination, but I don't see where it would proscribe 
moderately unhealthy experiences that one might learn something from.

So the nachash presented Chava with some reasonable arguments, and 
appealed to her emotions, advising her that there could be some 
benefit -- some "tov", which was a concept that she did understand -- 
from disobeying G-d's command. And she fell for it, because although 
there was some "good" to be gotten from this act, it was still 
not "right". But 'right' was something she did not understand.

That's the point I'm trying to underscore, and I do not think that it 
contradicts the Rambam or anyone else. That Adam and Chava understood 
good and bad even before eating from the tree. And then, after eating 
from the tree, they suddenly gained a new insight, that even though 
something is "good" -- for example, pleasurable -- it might still 
be "wrong" -- that is, *morally* wrong, improper, evil.

And a simple way to remember this, is by translating the tree's name 
not as the tree of knowledge of "good and evil", but of "right and 
wrong". (In other words: I find the word "good" to be ambiguous, 
referring either to emotionally good or morally good. By using the 
word "right" for moral good, we can clear up the confusion a bit.)

Akiva Miller