[lit-ideas] Re: Necessity is not an established fact, but an interpretation

  • From: Donal McEvoy <donalmcevoyuk@xxxxxxxxxxx>
  • To: lit-ideas@xxxxxxxxxxxxx
  • Date: Sun, 28 Aug 2011 01:55:11 +0100 (BST)

Necessity could be limited, by stipulation, to logical necessity or 'laws of 
logic': but then, if there are physical laws, what term do we use to describe 
why, given a law of physics and some initial conditions, then (logically) a 
certain conclusion must follow? Whatever term, it would seem to be a surrogate 
for a kind of necessity.

The necessity is not simply one of logical deduction but follows only because a 
law of physics is given, and it is given as a necessity, albeit a physical one. 
In other words, any law-like connection can be also described as a necessary 
connection. For Popper, there is logical necessity (if we want, these are the 
'laws' that prohibit something as not being possible in any logically possible 
world) but also physical necessity or natural laws. These natural laws of the 
physical world prohibit something as not being possible in the actual physical 
universe (though it is conceivable, or logically possible, that another 
physical universe could operate with different structural laws).

Of course, this means that 'natural laws' are logically contingent as it is not 
self-contradictory to imagine a universe where they would not hold. But that 
they are logically contingent does not mean they do not assert structural 
properties for the actual universe that are seen as invariant and unalterable 
in that actual universe: as "necessary" in that universe. So if 'E=mc2' were 
such a 'natural law' or structural property of our universe, then it would be 
correct to say that asserting this law is to describe the existence (or fact) 
of a kind of physical necessity: and so the 'necessity' asserted by the law is 
a fact, as well as being an interpretation. It may also be an 'empirical fact', 
albeit that all this may mean is that it may be a 'fact' the truth of which is 
open to testing by observation, and which may even survive the most rigorous of 
those tests we can devise.



--- On Sun, 28/8/11, Robert Paul <rpaul@xxxxxxxx> wrote:

    >I don't know what it would mean for necessity to be a fact or not be
    a fact.>

Well, an example might be the 'necessity' posited in the equation "E=mc2": this 
equation is either true, in which case the posited 'necessity' is a fact, or it 
is false, in which the posited 'necessity' is not a fact. I have previously 
alluded to the more sophisticated point that we can also treat "E=mc2" as 
asserting no 'necessity' but simply no counter-example to itself, in which case 
it could be true (because in no actual universe is there ever a 
counter-example) yet there be no kind of physical necessity to this absence of 
any counterexample: however, this would not alter the position that, if it were 
so treated but were 'false', its falsity would nevertheless show there is no 
necessity of the "E=mc2" kind.

<snip>    

    <As far as I can tell, scientific 'laws' are empirical
    generalizations; they are not necessary truths or true 'of
    necessity.' That is, if they're falsifiable, they can't be true   
necessariy.>

This only holds if we restrict "necessary" to what is logically "necessary". 
But if there are any 'laws of nature', these posit something as "necessary" in 
a sense distinct from logical necessity. My example of UGs, rather than 'laws 
of logic', indicated I was referring to what was "necessary" in a sense 
distinct from what is logically necessary. Perhaps it is necessary to make this 
clearer?

Dnl
Ldn



    

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