poltr1 asked about who -- conservatives or liberals -- uses logic more.
I spent far too long writing an answer, so I'm going to preserve it as an entry of my own.
People in general like to feel that they are
making their political choices based on logic and sound rational
reasoning, but in reality almost all of us make our choices based on
emotional or intuitive factors and then look for logical arguments to
back up the answer we wanted. This is more or less equally true of both
left and right leaning voters. This means that a successful candidate
is always actually appealing to emotions, values, and prejudices, but
since we feel more comfortable about ourselves when we have a nice
veneer of rationalization to justify our choice, it's also very useful
to present a superficially logical case.
A truly logical case
for a candidate is a very complex argument. It requires considering
many issues, pulling out a lot of evidence, justifying each piece of
evidence not merely in its superficial veracity but in its relevance to
the whole argument and its importance relative to other evidence.
Important pieces of contrary evidence cannot be ignored or lightly
dismissed; they must be rebutted in detail. All of the pieces must be
brought into a logical whole, and a case must be made that the goals
the candidate is campaigning on are all achievable together even though
they compete for finite resources.
In today's world of 30 second
TV spots and two minute answers to questions even in debates, nobody
has time for real, fully developed logic. If the candidate does make a
real, logical case, at book length, almost no one will read it (though
many will talk as though they did). Nobody genuinely wants logic. They
want a simple, easy to follow case that feels logical.
will I mention my own partisan opinion. The success of the Republican
party in the modern political era (starting with the 1980 campaign) can
be traced straight to their superior understanding and more effective
embrace of the above ideas. Conservatives put a lot of effort into
framing the terms of the debate and choosing the labels that will be
attached to people and issues while tricking liberals into arguing
about substance. (Why do we call the people who want to outlaw abortion
"pro life"? Because the right knows how important labels are and they
fought hard for it, while the left worried about the issue.) Then, once
they've written the dictionary, they can keep reinforcing their
emotional message with the semantic content of words. Because the
emotional message is in the terms themselves, they can devote a lot of
effort to giving their arguments the appearance of logic. They choose
their evidence carefully, not for being the best evidence but for being
the most convincing in a sound bite. Because they can state
their evidence quickly and they don't need to explain it, they have
more time to build the argument on top of it with superficial logic.
It's actually more logical to present more evidence and explain it
better, rather than focusing on the conclusion.
Republicans are very good at appearing more logical than they are.