26359Re: [evol-psych] Re: Scientific justifications
- Aug 3, 2003Having spent about 20 years of my life defending scientific realism against
confusion of various kinds, I don't want to spend too much more time on it.
My main claim in this discussion has always been:
TRUTH =/= CERTAINTY
(Where '=/=' means "is not the same thing as".) Here's another way of
expressing the same simple idea:
P IS TRUE =/= P HAS PROBABILITY OF 1
A sentence is true in much the same way as a man is an uncle. When your
sister in Antarctica gives birth, that makes you an uncle. You don't have
to know that she is in Antarctica, or that she has given birth, in fact you
don't even have to know that you have a sister! But as a matter of brute
fact, if she really is your sister, and she really has given birth, then
you really are an uncle.
When things are arranged in a particular way, any sentence that says they
are arranged that way is true. You don't have to believe it with any degree
of confidence, in fact no one has to believe it at all. But as a matter of
brute fact, if the words in the sentence really refer to those things, and
those things really are arranged in the way the sentence says they are
arranged, then the sentence really is true.
So truth is a simple, "transparent" sort of relation between sentences and
the real world. By contrast, the degree of confidence a person can have in
one of his beliefs is not at all simple or "transparent". Whatever we call
it -- confidence, certainty, justification, probability, whatever -- it is
not at all like being an uncle. It is a complicated, contextual sort of
attribute -- more like being "generous" (to pick another human
characteristic out of the air).
There are lots of generous people who are not uncles, and lots of uncles
who are not generous. There are some generous uncles, but there is only a
loose connection between being generous and being an uncle. Similarly,
there is only a loose connection between feeling justified in believing
something, and that belief's actually being true. You can feel very certain
about one of your beliefs, and yet still be wrong. Conversely, you can feel
very uncertain about it, and yet it can still be true.
Robert Karl Stonjek writes:
> I think most physicists believe-- I'm happy enough with that. Strictly speaking, truth and falsity are
> they are searching for models
> which accurately reflect nature.
attributes of declarative sentences of a language. But we can stretch usage
a bit and speak of other representational media as being more or less
"accurate". The more accurately a model reflects reality, the "truer" it
is. This usage meshes quite smoothly with ordinary talk of maps (say) being
"right" and "wrong" when they more or less accurately capture features of
the terrain. For example, early maps of North America showed California as
an island. These maps were wrong -- stretching the word a bit, they were
"false". They were false because as a matter of brute fact the Baja
California is attached to the rest of America. Given that blue areas stand
for water, brown areas stand for land, etc., in respect of this detail
these maps expressed a falsehood rather than a truth.
> Modelling is not the same as-- No, but being an accurate model is closely analogous to being a "true"
model, and being an inaccurate model is very closely analogous to being a
> One can say that a model is true,-- This is an example of the sort of confusion of truth and certainty I
> if we stretch the word a bit, but
> most models are accepted as
> accurate approximations to
> within the parameters thus far
> tested by experiment or
have been complaining about. Any hypothesis (theory, model, etc.) is a
guess. If it's a lucky guess, then it's true (accurate), and if it's
unlucky it's false (inaccurate). But the extent to which a hypothesis
(theory, model, etc.) is ACCEPTED AS true (accurate) is a measure of OUR
CONFIDENCE in believing it. Its actual truth (accuracy) or falsity
(inaccuracy) is a different thing altogether.
> No-one can say that "inflation-- No one can say it with certainty, but surely we can say it without
> theory" is true, for instance, even
> though the basic principles of the
> model are now generally
> Considering the sparseness of-- Agreed, but who needs to say it with certainty?
> historical knowledge that is
> bound to plague disciplines like
> Evolution and its various
> branches, one can not say with
> any certainty that any models are
> Rather, they explain certain-- They wouldn't explain those phenomena unless we assumed the explanatory
> phenomena, though other
> phenomena may contradict it, and
> they seem to predict some results.
hypotheses were true. To the extent that models cannot be understood as
true, they fail to explain. The basic outlines of evolutionary theory are
not models, and they can be expressed as non-metaphorical sentences of a
language like English, and they are literally true or false. My guess is
that most of these sentences are true.
> It is quite common for more than-- Arguing for the greater "accuracy" of one model over another is the same
> one hypothesis to model the same
> phenomena where there is a
> sparsity of observational or
> experimental data. Advocates of
> each model do not generally argue
> for the truth of their model, but
> argue instead that their model more
> accurately reflects the nature of the
> phenomena so modelled.
thing as arguing that it more closely approximates the truth. The word
'true' is sometimes avoided (in physics, mostly) because these models
consist of mathematical formalisms rather than plain English sentences. But
many of them can be roughly "translated" into such sentences, and those
sentences are literally true or false.
> There are also unprovable-- I would say that no hypothesis is provable, at least not in the sense
that a mathematical theorem is provable. But again, provability and truth
are entirely different things.
> For instance, if we made the claim-- This is another an example of the sort of confusion of truth and
> that no two snowflakes are the
> same, then this can only be true
> until two identical snowflakes are
certainty that I have been complaining about. The claim that "no two
snowflakes are the same" is either true or false. We can have varying
degrees of confidence in it. Suppose at first we are quite confident that
it is true. But later, when we discover two exactly similar snowflakes, our
confidence goes from "quite high" to "zero". Despite the big change in our
confidence, its truth-vale remains completely unaffected. It is false, and
importantly, it always was false. Before, we just didn't know that it was
All the best -- Jeremy Bowman
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