Re: Randomness
- From: "Mitchell Coffey" <m.coffey@xxxxxxxxxxxxx>
- Date: 17 Nov 2005 08:19:39 -0800
Bobby D. Bryant wrote:
> On Thu, 17 Nov 2005, "John Bode" <john_bode@xxxxxxxxxxx> wrote:
>
> > The word "random" gets tossed around a lot on t.o., and I just want to
> > make sure I'm understanding and using the term as intended.
> >
> > An event is random if previous events do not affect or predict future
> > events. A coin toss is random because previous tosses do not affect or
> > predict the next toss (assuming a fair coin, anyway). Tossing 50 heads
> > in a row does not change the probability that the next toss will be
> > tails.
>
> That's because the tosses are _independent_ random events. The general
> definition of randomness does not require independence. For example,
> when a lottery machine drops the numbered balls into its "output" tube,
> the selections are not _independently_ random because once a ball is
> removed from the tumbler the probabability of selection for all the
> remaining balls is changed. OTOH, if you put each ball back in the
> tumbler before selecting the next one, the selections would then be
> independent. (Ignoring the fact that the whole thing is a determinate
> mechanical system, above the quantum level.)
>
> Also, re the fair coin, a system can be random even if its states do
> not all have the same probability. E.g., the flip of an unfair coin
> is still random; it's just that its outcome doesn't have a flat
> probability distribution. (The definition of "fair" is "has a flat
> probability distribution".)
>
> Creationists almost always miss that fact, and sometimes their arguments
> suffer as a consequence. To give an irrelevant example (because I can't
> think of any relevant ones right now), we think of the motion of a
> molecule in the air as random, but nevertheless the position of the
> molecule at any time is more likely to be close to the ground than
> twenty miles up, because there are other effects that bias the movement
> of the molecule (i.e., gravity). That doesn't make the molecule's
> movement un-random; it just makes it un-"fair".
Isn't evolution the exactly relevant example? Biological evolution by
common descent has certain predictable pattern, when plotted
appropriately. This includes the wide-branching bush or tree pattern,
and the tendency toward for more fully-featured creatures (I left the
relevant definition of "complexity" and "organization" at my other
office; I haven't a clue where I put my "information" def.)
Both patterns appear because of the nature of evolutionary mechanisms,
and the expansion-into-a-vacuum phenomenon. (And because people tend
to focus on patterns, to note the fish and not the sea, and only to
notice the big stuff: most evolution, to this day, goes on at the
single cell level, producing ever-different -- single cells.)
Mitchell Coffey
.
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