Re: Opinions as Evidence (Was: What is to be done?)

Hal Finney (
Tue, 25 Mar 1997 18:08:54 -0800

Robin Hanson,, writes:
> There are lots of explicit models of situations like these, most but
> not all using Bayesian inference, and the robust result is that other
> people's opinions should be given a lot of weight, typically much more
> than the weight given to your personal experience. In fact, it turns
> out to be difficult to explain persistent divergence in opinions.

I thought this was the crux of Robin's post, and it is a very surprising
result to me. However it seems hard to frame the question cleanly. One
could ask, in most areas where there is a difference of opinion among
people, is the majority or the minority more likely to be correct? It
would not be surprising if the answer were that the majority was more
often right. However this would not establish that I should give more
weight to others than to my own experience, because I may not be typical
of average minority members. I'd like to hear more about the kinds of
reasoning or studies which lead to the conclusion above.

As Robin indicates in his last sentence, there is even the germ of a
contradiction here:

If the opinions of other people are really very valuable and generally
an accurate indicator of reality, then I should be well to copy many or
most of their opinions. In particular, I should copy people's habits
of giving credence to other people's opinions. But, it seems to me that
most people aren't that easily persuaded by other people's opinions when
they disagree on some issue. So if I copy that behavior then I shouldn't
rely that much on other people's opinions, contradicting the conclusion
that I should.

Of course, this rests on my claim that most people prefer to decide
for themselves rather than listen to other people. It could be that I
have mostly associated with individuals who are unusual in this regard,
or I could simply be mistaken in my perceptions. Perhaps I am focusing on
just those areas where they differ, ignoring the vast body of accumulated
knowledge which everyone shares. Or maybe people like to exaggerate
their uniqueness and downplay the extent to which they follow the crowd,
for cultural reasons.