search form is not aligned vertically - Page 2

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Re: search form is not aligned vertically

...

A conjunction of a false empirical statement with any number of
other true statements, empirical or not, is false.

It depends on how you are counting what is empirical and what is
a priori. There is much vagueness in all of this.

Quite often a priori is used to mean that nothing we could find
out about the world can affect our commitment to the statement.
Thus, 2+2=4 is a priori true no matter that two volumes of sugar
in two volumes of water does not make for any four volumes we can
see.

There are several ideas here, one being that an a priori
statement is something able to be known without gathering
evidence. What sort of evidence? In maths, one can know a
statement to be true on the evidence of other mathematical
statements. No, what is meant is that an a priori statement is
one that can be known without reference to any a posteriori
evidence.

So, what is a posteriori evidence when it is at home? It is what
is known after examining the world. What about the world? Not the
things we know about all possible worlds! So *what*?

Well, perhaps it is empirical evidence? So what is empirical
evidence? The sort of thing a detective gathers while rummaging
around? What field scientists gather? What Tycho Brahe was so
famous for, compilation of accurate low level astronomical data.
How low? How high can it go before it stops being empirical?

Well, one can talk for ever about all this. It is arguable that
while mathematical statements are true in all possible worlds,
the idea that every object in a state of uniform motion tends to
remain in that state of motion unless an external force is
applied to it might be rejected as being *untrue* in another
possible world if not in this. It is high level, away from data
gathering and stands or falls as a package with a whole theory if
there is nothing better. That makes it high level, not
necessarily a priori.

--
dorayme

Re: search form is not aligned vertically

Obviously, but a much more worrying problem is when statements _depend_
on each other.

All I'm saying is we started with something like (A and B and C and D)
not with something like (D -> A and B -> C) or something, which would
have been much worse if D were disproved, because you would also lose A,
B and C.

Yes, but it's an important subtlety. Yes experience of some sort
probably was involved somewhere back along the way of discovering the
laws of motion.

As I think you're also saying, a related but more relevant and easier to
deal with question is what are the consequences, and possible worlds are
a good way to express this question.

So a possible world in which my car were blue instead of red is not too
hard to imagine. But a possible world in which any one of the laws of
motion were different might be barely recognizable, or not even
possible.

If you changed the three laws, energy wouldn't be conserved in all
reference frames, you could have perpetual motion machines, all kinds of
stuff.

It's easy to imagine things like time travel, but when you think them
through, it's becomes hard to see whether they could really work or
whether everything else would unravel.

The same goes for strange but true things in our world. A good example
is a gyroscope. When you play with one of those things it feels weird
the way it sort of balances and kicks back when you try to tip it over.
It seems very easy to imagine that it could behave differently. But
Newton's laws tell us that it couldn't have, not without everything else
that we find familiar and intuitive breaking down too.

There's a difference between a possible world and an imaginary world,
and many imaginary worlds aren't possible.

[...]

I suspect the three laws of motion are true in all possible worlds.

[...]

But I'm not so sure it is possible for it to be untrue. It's easy to
imagine, like time travel, but not so easy to actually work out a
consistent world in which it wasn't true.

Re: search form is not aligned vertically

...

'a priori' and 'a posteriori' are epistemological concepts, not
logical or psychological or historical. 'a priori's mains that if
some statement has a priori status, that statement can reasonably
be believed without needing to be backed by any empirical
evidence. A person can rightly come to see its truth by mere
reflection on it or by seeing how it can be proved or be deduced
(in the mathematical or logical sense) from necessarily true
statements.

I am not trying to contradict anything you are saying by the
above. No one has ever seen the truth of any necessary statement
without having, as a historical fact, experience of the world.
But the relevance of experience to the a priority or a
posteriority concerns something rather more timeless and pointed,
namely the support that empirical knowledge gives to bolstering
the reasonable confidence in belief. Nothing at all can boost my
confidence that 2+2=4. I do not think the same thing applies to a
set of physical laws. I know you do.

I am worried that it is you who is applying the flawed
imagination test for a priority or necessity. Let me explain.

I could not agree more about that conceivability is a dangerous
test for necessity or impossibility. By the very same token, you
need to be careful not to suppose that something is logically
necessary because you (and others) can't work out how else to
configure the laws that would explain our world. Thinking
alternative theories is not a regular job! It is a task for the
most creative imagination and must sit in a whole bed of
empirical connections. Newton's laws do not seem to me to be
quite as immune to experience as some of the maths that is
developed. There could come a time when none of the present
written laws or ways of thinking about how the cosmos works,
mechanics included, gets a mention, a whole set of different core
laws might come about. There could not - *as easily* to my way of
thinking - come a time when 2+2 did not equal 4 or (p and not-p)
be true.

Newtown had a whole cosmology, it included the idea of absolute
space. At one time in human scientific evolution, many of us
might well have had as much confidence in the a priority of the
proposition that space was absolute, we might have had no means
by which to think anyway different. It took a lot of maths and a
lot of physics to turn our perceptions on this around.

To "actually work out" something like this is not something that
can be done on a lazy afternoon. It might need a big human
scientific leap. That may be why it may so hard rather than that
it is impossible.

--
dorayme

Re: search form is not aligned vertically

Yes, good clarification.

[...]

Indeed, and history is littered with examples. I don't actually rule out
time travel myself.

I think absolute time was more the problem. Newtonian space was a nice
flat 3D Euclidean space everywhere with no preferred fixed point or
direction accompanied by an absolute ticking clock.

Yes, and still a priori-- it comes from trying to make sense of
electromagnetism. If you stick with a speed of light that works like any
other speed (goes slower if it's catching you up etc.) you will arrive
at contradictions in electromagnetism.

But I believe Newton's laws of motion are still correct even in curved
4D Minkowski spacetime.

Nothing seems to be more fundamental to physics than the symmetries that
result in conservation of energy and momentum. All the strangeness of
special relativity can be understood as a way to square those
conservation laws with a speed of light that's constant everywhere.

Re: search form is not aligned vertically

...

There was a famous experiment that found the speed of light was
not different in various directions. It encouraged folk not to
believe in an ether and so on. The data gathered by Michelson and
Morley was low enough level empirical stuff for us to be able to
say that had they found otherwise, then a lot of other higher
level theorising would be rather different. Is it possible you
are confusing a conditional necessity with an absolute one?

We do not know what the future holds, we do not know how quantum
physics and particle physics generally will be married to more
cosmological large distance theories. I would be wary of
declaring a set of high level physical laws to be on the same
level of necessity as mathematics.

I have more sympathy with your view than I have revealed. It has
always been a thought of mine that when we finally get the
ultimate truth in physics, it will be seen to be absolutely
necessary. It is just that I don't think we have got there yet.

--
dorayme

Re: search form is not aligned vertically

[...]

The Michelson and Morley experiment was very important, but there is
also a theoretical requirement for the speed of light to be the same in
all reference frames: otherwise Maxwell's laws would be different
depending on what speed you were moving at since the speed of light is a
constant in those equations.

Certainly, but finding the ultimate truth may be helped by separating
the physics from the metaphysics in what we do know.

Much of the apparent necessity in physics may just be internal to the
maths of the system we use to represent our observations-- it may be
that it tells us little or nothing about the mind of God after all.

Re: search form is not aligned vertically

And if MM had found quite different? The whole game would be
changed. The laws you are saying are perfectly and absolutely
correct would hardly merit such an accolade if they were found to
be useless and a quite different set of laws was developed to
explain things.

I am doubtful. Physicists will likely get on fine without
metaphysics.

--
dorayme

Re: search form is not aligned vertically

[...]

But could they have possibly found different given what we already knew
about electromagnetism? Of course this question is easier to ask with
hindsight.

[...]

They already use metaphysics all the time, since mathematics is part of
metaphysics (well, most of it really, so I probably just should have
said "separating the physics from the maths").

Re: search form is not aligned vertically

This is an interesting question. When Maxwell came up with his
equations to describe elecromagnetism and scientists accepted
them, this set certain givens against which people could reason
about what follows, what does not and so on. But we cannot jump
to the conclusion that the consequences qualify as necessary
truths. They may necessarily follow an accepted theory, but if
that theory is not necessarily true then neither are its
consequences.

What I said I suspected before is looking more likely, namely
that you are talking some sort of *relative* a priority and
necessity.

It is slightly unusual (in philosophy and, of course, in... what
usenet group is this? ... oh yeah... in web authoring) to think
of maths as metaphysics. It is metagroceryshopping and
metatoomanyotherthings. Why, hells bells, it is even
metametaphyics when we discuss the *number* of gods there might
be. <g>

I have been meaning to add at some stage that while strictly a
priority is an epistemological concept that can be argued to be
black or white (either empirical matters strengthen them or not;
if not, white; if otherwise black with a posteriority taking
over), I have some sympathy with the idea that it admits of
degrees. The closer a proposition is to low level empirical
matters, the further is it from being able to be known without
looking. The higher up it goes, especially as it is embedded in
very will accepted theory, the harder is it to see how it is
affected by data. But in the end, not maths but, for now I think
the whole show must be on behalf of the facts (in the Korpela
sense) and are ultimately to be voted out by them if they are not
right. That is a sort of sophisticated empiricism which yet gives
a nod to high reasoning away from the lowly.

--
dorayme

Re: search form is not aligned vertically

[...]

By far the best book I ever read on metaphysics was Kant's Prolegomenon
to Any Future Metaphysics and according to that mathematics is a subset
of metaphysics (unless I misunderstood it of course...)

According to that, metaphysics is just anything synthetic and a priori.
You may of course think, like Russell, that maths is analytic, but
that's another discussion.

An example of a metaphysical judgment, according to Kant, is the
statement that the shortest distance between two points is a straight
line.

[...]

Yes, I think you're on the right lines with this, and IIRC Quine had a
similar idea.

It was probably this I'm thinking of: http://www.ditext.com/quine/quine.html

Re: search form is not aligned vertically

I tend not to think of analyticity or syntheticity these days,
they seem not so productive and are full of difficulties and
inbred problems and vaguenesses.

Metaphysics is about matters of ontology beyond the sciences. For
example, broad questions of what exists beyond the scope of
science. Like are there gods, minds, material things, classes,
numbers?

Maths is down and dirty detail compared. Maths will go on and on
about the various numbers and their relations and all sorts of
things but the metaphysical questions are not *within* maths but
about maths. The philosophy of maths is not maths and
metaphysical questions about mathematical objects and properties
belong to the philosophy of maths. So I have a different idea
about these things. Kant is so ... is so ... well... a few
hundred years ago! <g>

--
dorayme

Re: search form is not aligned vertically

Ah, but _if_ time travel is at all possible (-which I, myself, rather
doubt,) the only possible way it can be accomplished is via the means
you and I were discussing above: gravitational influences.  I know
there are various postulates on time-space bending or "warping", etc.,
but I think at the present time we just don't know enough about it to
say for sure.

--
Neredbojias

http://www.neredbojias.org /
http://www.neredbojias.net /

Re: search form is not aligned vertically

[...]

The motivation for it is usually given as the principle of equivalence.
This is the fact that sitting inside a box with a load of other objects
in no gravitational field is indistinguishable from being in the same
box in freefall.

In Newton's system this is a coincidence arising from the facts that
gravitational force and acceleration due to a given force are both
proportional to mass: gravity pulls heavier things harder but heavy
things are harder to move.

Re: search form is not aligned vertically

In comp.infosystems.www.authoring.html message <dorayme-E1118C.145700160
82010@news.albasani.net>, Mon, 16 Aug 2010 14:57:00, dorayme

False statements need to be corrected.  When one knows what is wrong
with them, one can safely treat them, in circumstances where the error
makes no significant differ3ence, as if they were true statements.

--
(c) John Stockton, nr London UK.  ???@merlyn.demon.co.uk  Turnpike v6.05  MIME.
Web  <URL:http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, & links.
Check boilerplate spelling -- error is a public sign of incompetence.
Never fully trust an article from a poster who gives no full real name.

Re: search form is not aligned vertically

In article

...
...

Perhaps they do not *all* need to be corrected.

What! Are we in agreement? This is a serious matter, is agreement
allowed on usenet? <g>

--
dorayme

Re: search form is not aligned vertically

In comp.infosystems.www.authoring.html message <dorayme-297EDC.093242180
82010@news.albasani.net>, Wed, 18 Aug 2010 09:32:42, dorayme

Not those which are obviously false or obviously unreliable.  But those
misleading the readership need to be corrected - like what you have
written in this thread.

--
(c) John Stockton, nr London UK.  ???@merlyn.demon.co.uk  Turnpike v6.05  MIME.
Web  <URL:http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, & links.
Check boilerplate spelling -- error is a public sign of incompetence.
Never fully trust an article from a poster who gives no full real name.

Re: search form is not aligned vertically

In article

OK, lets quarrel! What have *I* said that misleads the readership
any more than anyone else in this thread?

--
dorayme

Re: search form is not aligned vertically

In comp.infosystems.www.authoring.html message <dorayme-BE4E3F.141050200
82010@news.albasani.net>, Fri, 20 Aug 2010 14:10:50, dorayme

I have not said that you have made a misleading technical statement;
rather that you have shown a silly attitude to the need for accuracy.

RF made, inadvertently no doubt and due to ignorance of any alternative,
an untrue statement or clear implication.  If he had known better at the
time, he would have been able to write something accurate instead.  That
needed to be corrected.

--
(c) John Stockton, nr London UK.  ???@merlyn.demon.co.uk  Turnpike v6.05  MIME.
Web  <URL:http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, & links.
Check boilerplate spelling -- error is a public sign of incompetence.
Never fully trust an article from a poster who gives no full real name.

Re: search form is not aligned vertically

In article

....

My silly attitude? It cannot be my view that not all statements
need be 100% accurate because this is *perfectly* correct.

Wonder if it is my feeling that for many of us it would be as
easy to copy/paste a poster's code (snippets often) into a text
editor and drop it on to a browser as studying your facility and
getting handy with it that is bothering you?

When I hear many more folk than just you saying how much easier
it would be, I will start to take notice of the idea that rf's
statement is unacceptably inaccurate. Till then, I continue to
think it a perfectly reasonable thing to say.

--
dorayme

Re: search form is not aligned vertically

In comp.infosystems.www.authoring.html message <dorayme-4B69B9.091759220
82010@news.albasani.net>, Sun, 22 Aug 2010 09:17:59, dorayme

No.  It is almost always easier, for any one instance of a task, to use
a familiar method than it is to use a new one.  But that does not make
it necessary to do so; therefore, it was appropriate to correct rf's
assertion.

Remember, too, that I posted exact instructions for using my method to
test the OP's page; understanding my method could be left to later.

A copy of my page can also be used to test JavaScript code or as a
programmable calculator;
or, in IE, to test VBScript code,
or to pack (multiple) paragraphs of text such as this one.

Frankly, the modicum of respect which I previously had for your opinions
has been completely destroyed by your postings in this thread.  Do you
happen to work at the Sydney Observatory?

--
(c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk  Turnpike v6.05  MIME.
Web  <URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.