From: Lee Corbin (lcorbin@tsoft.com)
Date: Tue May 27 2003 - 22:26:02 MDT
Dan had posted
> For the full essay, see http://home.sprynet.com/~owl1/irrationality.htm
One of the problems I have with Michael Huemer's points---although
agreeing that this paper is very good and on the whole makes
valuable points---is when he writes
In one psychological study, subjects were exposed to evidence
concerning the deterrent effect of capital punishment. One
study had concluded that capital punishment has a deterrent
effect; another had concluded that it does not. All experimental
subjects were provided with summaries of both studies, and then
asked to assess which conclusion the evidence they had just
looked at most supported, overall. The result was that those
who initially supported capital punishment claimed that the
evidence they’d been shown, overall, supported that capital
punishment has a deterrent effect. Those who initially opposed
capital punishment thought, instead, that this same evidence,
overall, supported that capital punishment had no deterrent
effect. In each case, partisans came up with reasons (or
rationalizations) for why the study whose conclusion they
agreed with was methodologically superior to the other study.
This points up one reason why people tend to become polarized
(sc., to adopt very strong beliefs on a particular side) about
political issues: we tend to evaluate mixed evidence as
supporting whichever belief we already incline towards—--
whereupon we increase our degree of belief.
I agree that everything he has said here is true; I simply don't
think that evolution erred to make us this way. But first of all,
a point about PCR (Pat-Critical Rationalism).
It must be held in mind that mixed evidence DOES NOT knock down a
belief! Mixed evidence does not refute anything, and a conjecture
subjected to only "mixed evidence" survives the criticism, perhaps
unscathed. So therefore it is in the nature of how our learning
take place---through conjecture and refutation---that this tendency
within us arises. And so far as we know (considering the absence
of other beings who think a lot different from us), this is a good
thing.
He also wrote about the very same subject,
b. Selective attention and energy:
Most of us spend more time thinking about arguments supporting
our beliefs than we spend thinking about arguments supporting
alternative beliefs. A natural result is that the arguments
supporting our beliefs have more psychological impact on us,
and we are less likely to be aware of reasons for doubting our
beliefs. I think that most of us, when we hear an argument for
a conclusion we disbelieve, immediately set about finding "what’s
wrong with the argument". But when we hear an argument for a
conclusion we believe, we are much more likely to accept the
argument at face value, thereby further solidifying our belief,
than to look for things that might be wrong with it.
Well, for some reason this strikes me as only natural. Suppose
that you were assessing the impact of a flock of birds in the
distance; it's a little bit disconfirming of your belief that
the best hunting ground lies in the other direction. This ought
to give you a little pause, and to perhaps cause a bit of
re-thinking---but you'll probably just try to fit it in with
your pre-existing beliefs. Sounds perfectly fine to me. But
suppose that you see the flock in the direction which you
already to believe to lie the best hunting; as he says, you'll
experience some reinforcing gratification.
This is illustrated by the capital punishment study mentioned
above (section 5, d): subjects scrutinized the study whose
conclusion they disagreed with closely, seeking methodological
flaws, but accepted at face value the study with whose conclusion
they agreed. Almost all studies have some sort of epistemological
imperfections, so this technique almost always enables one to hold
the factual beliefs about society that one wants.
Well, as the skeptics say, extraordinary claims demand extraordinary
evidence! If someone presents me with what appears to be an airtight
argument that people are not affected by incentives, and that (say)
redistribution of income won't affect total production, then I'm going
to apply much stronger filters to that argument than I would its simple
converse. This too is only natural, isn't it?
Finally, along these lines, a good task for all those who find our
methods of reasoning---including the very well-documented ways in
which we err on probability problems (see the studies by Kahneman,
Slovic, and Tversky)---is to explain how it is that we evolved to
be predictably less than perfect reasoners, even given more than
ample enough time to have had it corrected.
Lee
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