Condorcet voting systems are more complicated than range voting
(and the best Condorcet voting systems are much
more complicated).
This probably already is sufficient to make them politically
unadoptable.
Range voting is more expressive than Condorcet voting.
Condorcet voting systems are not usable on many of today's
voting machines.
But range voting
is usable on every voting machine in the USA, including
noncomputerized ones
(and usually easily), right now, without modification and without reprogramming.
That makes range more adoptable with less pain and expense.
The fundamental idea (by Condorcet) which lies behind these systems, also is
satisfied by range voting, i.e. there is a (nontraditional
but arguably better) way to define "Condorcet system"
that (a) is compatible with all previous applications of the term to
voting systems found in all previous political science books, and
(b) under which range voting
is also a "Condorcet system."
All Condorcet systems exhibit "favorite betrayal."
In a 3-way election like
Bush v Gore v Nader 2000,
voters are tempted to
exaggerate their good and bad opinions of Bush and Gore by artificially ranking them
first and last, even if they truly feel Nader is best or worst.
If that happens, then Nader cannot win.
The result of that, over time, would be
self-reinforcing 2-party domination,
causing Condorcet not to be much if any improvement over
plain plurality voting.
There is good reason
to believe (or at least suspect) that this pathology will happen
with every Condorcet system, but that it will not happen with range voting.
For example about 90% of Australians
vote in this exaggerated manner on their
rank-order ballots.
Meanwhile, with range voting, even if every voter exaggerates and ranks Gore=99, Bush=0
(or the reverse) then Nader still has a very realistic possibility of winning
(without any ties required) so there is no obvious reason we will
get 2-party domination.
Counterintuitively, we can prove that (under reasonable assumptions about strategic voter behavior)
Approval and traditional-Condorcet voting
actually are not in conflict
(no-conflict theorem) and it
is plausible that range and approval voting
both will actually be more likely in practice to elect honest-voter Condorcet
winners, than "official"
Condorcet methods! [Summary of the model.]
And because strategic range voters generally vote approval-style, the same would
be true of range voting elections with strategic voters.
In other words:
To the extent range voters are strategic they will elect
Condorcet winners (indeed quite likely doing so more often than
"official" Condorcet methods);
whereas to the extent they are honest,
range voting should perform
better than Condorcet.
Even if you don't quite totally buy all that, we think the logical force of this still
should be enough to convince you that,
in practice, one cannot expect any great advantage for Condorcet methods over the
much simpler range voting system.