Re: New A C Grayling book

In message <466efac7$1@xxxxxxxxxxxxxxxxxxxxxxxx>, michaeld <michaeld@xxxxxxxxxx> writes
Michael J Davis wrote:

In message <466da2a2$1@xxxxxxxxxxxxxxxxxxxxxxxx>, michaeld
<michaeld@xxxxxxxxxx> writes

Forgive me for some heavy snipping, this had got so long that it fell foul of my own killfile rules! ;-)

I'll only leave in the bits I wish to comment on, that's not to say the rest isn't stimulating, too!

So, let's be clear. If we take a model like Euclid, we start with a
number of premises and build a reticulum of logical connections. Some of
these have nodes where we recognise the 'truth' (based on the premises)
of the logical deduction. That provides a starting point for the next
series of connections.

In practice, however, if you use the 'network' model, there are areas
within the network that are unconnected. These may subsequently be
filled with a smaller scale reticulum of logical connections, or it may
just not be possible to go there.

I'm not entirely sure what you're saying. It's certainly the case that,
using logical deduction and starting from Euclid's axioms, you can't
identify any truths except those of Euclidean geometry; all the
conclusions of the logic are only valid in Euclidean geometry. Another
example of truth being contextual.

When I was a child in London, I used to travel by underground using the famous underground map. As a result I knew London as a series of patches around tube stations. I was quite old, nine or so, before I realised that some of the different patches overlapped and I could get overground from one bolt hole to another!

I think the nature of knowledge (and reason) is like that, we have these logical steps that get us from one reasoned station to another. And we can explore around each deduced point. But we can never be sure that we have fully mapped the area in between (or that there isn't something wonderful that remains undiscovered).

(Of course you can redefine the statements so that they include the
context - i.e. Euclidean geometry - in which case you can reasonably
assert them as being true in some more absolute sense. Same is true for
the non-mathematical example of a contextual truth I gave below.)

If we cannot get to a specific point by logic (however
multi-dimensional) then that may be because it is 'false' or because we
cannot get there. It doesn't prove that it is false, because we only
have the approach of human logic plus some tools - like mathematics -
that seem to have a reliable one-to-one connection with what we call
'reality' (or 'truth').

Well like I said earlier, logical deduction is only a subset of human
reason. I singled it out because it seems the easiest part to define in a
way that is independent of humanity (and other life forms) and their tools
for survival. Logical deduction per se cannot say anything about "external
reality", e.g. physics. The scientific process is fundamentally inductive
not deductive, and the crucial difference is that the process of
induction, unlike deduction, is not guaranteed to produce results that are
as reliable as the premises you put in. This fact is, I think, the root
cause of some of the objections below 1)-4) to making assertions of truth
in science.

I agree with the more general point though that there's no reason that
human reason should be sufficient to understand the whole of reality.

Yes. That is my main point that I wish to make to scientific atheists.

>I am not a physicalist. I can only make sense of "where" questions when
>we're talking about physical entities (and perhaps not even then). 7 is
>not a physical entity. It exists, but not at a particular point in
>physical space.

It exists at a particular point in logical space.

Right - also sometimes called Platonic space or Platonic reality. In case
you hadn't guessed - yes I'm a Platonic realist. (I prefer that term to
"Platonist" since sometimes the latter is taken to include Platonic
idealism, which I'm less enthusiastic about.)

"Platonic space" clearly isn't like physical space, but I suppose you can
answer "where" questions by showing where concepts like "7" are relative
to other concepts. For example you can construct 7 explicitly in the
framework of Peano arithmetic.

I'd forgotten that expression, I must review it. Thanks.

[snips]
>Yes I think you have it about right, though you'd have to ask those who
>hold sure a philosophy to be sure.
>
>I think there are a number of reasons that scientifically inclined people
>may be suspicious of the concept of "truth":

And I should also mention that only 3) is a serious challenge to the
concept of truth itself. The others are really reasons that it may be
unwise for we humans to assert truth (even if it actually exists).

Umm. I'll think about that.

>1) the possibility that asserting "truth" amounts to making an assertion
>with absolute certainty.

OK, I accept the reservation; as with all things what appears as truth
to us, may well depend upon our premises. But we are trying to identify
some thing that is invariant under all transformations (as a
mathematician may or may not put it!).

Very few things are invariant under all transformations. :)

;-)

[snip more]

Personally I subscribe (with some reservations) to a more instrumentalist
view of science as described for example in:

http://en.wikipedia.org/wiki/Instrumentalism

Thanks for that pointer...

I do think though that if you take an integrated approach to scientific
instrumentalism and make an effort to use language consistently then you
end up sounding like a scientific realist a lot of the time. In that
regard I usually find myself much more in agreement with the assertions
and language of scientific realists than with the pragmatists (such as
logical positivists and even more so the Popperians) even though I'm
probably closer to agreeing with the latter's philosophic fundamentals.

I have a love / hate relationship with Popper sometimes it's blindingly obvious, at other times it seems so reductionist as to be silly. (I just like the German title.)


Thanks for your interesting comments,

You're welcome. I hope that this and other recent threads will prove
helpful for your essay.

Thanks, I've saved our discussion away for later review...

Mike

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--
Michael J Davis
http://www.trustsof.demon.co.uk
<><
For this is what the Lord has said to me,
"Go and post a Watchman and let
him report what he sees." Isa 21:6
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