>Some care is needed with the application of Occam's razor.
>I believe that it is best used as a guide in the approach to a new
>issue.  That is, start with the simplest explanation and only make it more
>complicated if you then find that you have to.
>Sometimes the more complicated explanation is the right one.

        Exactly.  The principle is often stated as  "refrain from invoking
unnecessary causes".  But when they *are* logically indicated, they should
be invoked rather than evaded.
May I connect with the current furore about evolution in Ohio science
curricula?  Here's the 'hard core' of what I've sent main Cleveland
newspapers about this confusion.  The point is that in order to understand
biology you do have to invoke not 2 but 4 types of causes.  Those who
refuse to do so tend to resent & evade, rather than discuss.  And they tend
to assume a colony of bees is no more than biochemical mechanisms.
        The following is about as briefly as these matters can be set forth.


        It is helpful to begin by making clear what the term 'evolution'
means: the appearance of new life-forms  -  new species and bigger
categories genus, family, order, class, phylum, kingdom  -  over time.  It
is a scientific fact that evolution has occurred.  But this fact has no
necessary implications for theology.
        The idea that no new species have been created since the 6th day
belongs in a theological approach called deism, which went defunct a
century ago and needs no reviving.  Theism has superseded deism.
        Having accepted the overwhelming body of evidence that evolution
has in fact occurred, science wishes to explain it  -  to describe how it
happened, in terms of scientific laws.  Some progress has been made.  But
science cannot illuminate the 'why' question.
        It is perfectly possible to teach evolution as simple narrow
science, avoiding questions of final cause.  However, that is not the usual
approach of the neo-Darwinists, who typically assert that blind chance can
account for biology.  Their main PR agents  -  R Dawkins, L Wolpert, S
Weinberg  -  go out of their way to attack the common belief that the
incomparable coordinated complexity of biology bears the mark of
intelligent design.  They are aggressive atheists who wish to abolish the
theological 'why' questions.  They insert theological argument  -  however
crude  -  into the teaching of evolution.
        The proliferation of increasingly complex life-forms over time
requires explanation  -  ascription of causes  -  beyond what has become
standard evolution theory viz.  random mutation, natural selection,
genetics, and population dynamics  -  the four lines of scientific thinking
which have been synthesised into neo-Darwinism.  For this explanation, more
causes than just materials & chemical processes are required, as was
clarified in 1972 by one of my country's few famous biologists, Professor
John E Morton.   Using science as Aristotle of course could not, Morton
clarified the 4 categories of cause originally defined by Aristotle, in his
1972 'claret cameo', here paraphrased:

                What are the causes of my bottle of claret?
        The material cause includes the grape juice and the yeast,
materials transformed by the efficient cause into this peculiar substance
claret.  The efficient cause, as in Aristotle's prototypical example 'the
making of a statue', is the action of the yeast on the grape sugars and
some minor components, a process resulting in aqueous ethanol and some
minor chemicals characteristic of claret.
        But my bottle of claret has also a final cause: a person (named
Babich) exerted his will to organise suitable vessels & conditions for the
substances which are the material cause, and planned a sequence of
operations for the purpose of making claret by maximising the likelihood
that the efficient cause for claret would operate i.e.  the particular
biochemical action of the yeast on the grape juice leading to claret.
        Aristotle's formal cause is the 'claret idea' in Babich's mind.

        If a bottle of claret requires a final cause, how can it be
believed that a frog doesn't?
         What then can be said to explain  -  ascribe the causes of  -  an
organism?  The blueprints encoded in DNA are material causes, and operate
as parts of efficient causes through the several types of RNA and the many
enzymes essential for synthesis of proteins & other biochemicals; but DNA
is certainly not a final cause.  As Professor Morton has recently put it,
DNA is not the kind of thing that can cause other things as if paints could
leap from tubes to create a Turner, or vibrations & percussions form
themselves into a work of Mozart.  A person implementing a plan - a final
cause, like Aristotle's prototypical 'the man who resolves'  -  is the only
way such things can come to be.
        No amount of explanation in the categories of material & efficient
causes can suffice to explain life.  Dawkins & co grandly neglect half of
the 4 causes.
        Megatime is no substitute for purpose in the creation of
coordinated working ecological order.  It is notable that Dawkins always
describes evolution in language suffused with purpose, though he then
asserts it has no purpose nor final cause.
        If students are to be taught as fully & efficiently as possible,
they will need all these concepts clarified.  Mere assertion of materialism
(also called 'naturalism') will not suffice.

        Our care, or neglect, of the biosphere will depend on what we
believe about how and why it came to be.  If we bring up children to
believe vaguely that it came from nothing more important than the laws of
physics & chemistry, should we be surprised if they then fail to conserve
the biosphere?

        Religious scientists, such as Prof. Morton, and the whole church of
Rome, have had no trouble believing that evolution has occurred and is
indeed God's actual method of creating new species.  The idea that
evolution and creation are alternatives  -  mutually exclusive  -  is a
mischievous confusion.