[Avodah] Eilu v'eilu and mistakes

[Daniel Israel]

This is _not_ an attempt to re-open any recurring debates.  But my 
chavrusah and I had an interesting discussion and I'd like the 
chevra's input.

The basic question that we raised was whether in a machlokes 
rishonim we can say that sometimes one side is wrong, or whether we 
have to say all rishonim are right, even when they are arguing.  
The discussion then drifted to what lies between eilu v'eilu, and 
one side being right and the other wrong.

Which leads to these specific questions:

1) We see ev"e explicitly applied to Tannaim.  While the term is 
used on this list often enough in the context of contemporary 
issues, do we have a clear source which indicates that it remains 
applicable in the same sense as in the Mishna?  (The sense that I 
understand it is that the totality of Torah can't be expressed in 
human terms by a single opinon, and both sides in an ev"e represent 
an aspect of Torah.)

IOW, when contemporary poskim disagree on the correct bracha on 
rice cakes, is this ev"e?  If so, must we say it is just a 
reflection of a machlokes already implicit in the Tannaim?  Or can 
it be a "chidush"?  And if there are no "new" cases of ev"e, when 
was the cutoff?

2) I've occasionally seen achronim suggesting certain other 
achronim were actually wrong.  The examples I can think of involve 
claims that a certain achron was missing a certain source, or 
relying on an incorrect girsa.  But perhaps there are example is 
which one achron argues that another has incorrect s'vara as well.  
(I'm not talking about contemporary issues which are, so to speak, 
still being adjudacted by the poskim.)  My question is, is there a 
cutoff date before which we do not say that one side may be wrong?  
IOW, in a machlokes Rashi and Tosfos, for example, is it possible 
that one side is actually incorrect (even if we are not able to say 
who)?

3) Finally, does anyone want to propose an intermediate position?  
That is, are there some arguements which are not ev"e, but neither 
side is "wrong."  My chavrusa proposed something along the lines of 
"they are doing different things," but it didn't sit well with me.  
Any thoughts? 

--
Daniel M. Israel
dmi1 at cornell.edu