WE are all familiar with laws. Many are in the form of Acts
of Parliament. Our daily conduct is largely governed by
them. One of the simplest and commonest is the law which
requires traffic to keep to its own side of the road. We take
account of it almost every time we stir out of doors. In the
absence of such laws things would be left to chance. Civilization would be impossible. If there were no rule of the road,
the state of traffic on our highways would be chaotic.
We shall find later that all laws are not like Acts of Parliament, so we need a distinctive name for those which are.
"Governmental laws" suggests itself as obviously suitable.
And as a specified selection between alternatives cannot be
obtained without such laws we might also call them "selective laws". This title emphasizes that they forbid certain
things and demand others. We shall find several other equally
appropriate names later on.
We have shown in the preceding section that in the organic
world a specified selection between alternatives is obtained.
In the structure and behaviour of living organisms certain
things are forbidden and others demanded. So the laws of
biology are of the governmental type. At first sight it may
seem that all the laws of physics are of this type too. It is
quite customary to speak of them as though they all were.
Jeans does so when he tells us that God selected the laws of
physics out of innumerable possible alternatives. In saying this
Jeans expresses, we feel sure, a very prevalent belief, at least
among non-physicists, and a belief implied sometimes also
by physicists as when they speak of "forbidden" transitions
in quantum mechanics. Singer shows this belief when he says
that it is a sense of the reign of Law which the Greeks have
handed down to us.
It is an excusable belief. For the true nature of the laws of
physics is not immediately obvious, and their superficial
resemblance to those of a country and to those of biology, is.
The laws of biology are manifest in such requirements as that
a tulip flower shall have three external petaloid sepals and three
internal petals, that muscles shall contain glucose, that offspring shall resemble their parents, that dogs shall secrete
saliva at the prospect of food. The laws of physics are manifest
in such requirements as that planets shall move in ellipses,
that hydrogen shall combine readily with oxygen, that carbon
shall crystallize in octahedral and allied forms, that the acceleration of a particle shall be proportional to the force applied to it.
It is such lists which give the impression that those laws which
govern the behaviour of substance in the organic world and
those which govern the behaviour of the whole Material
Universe are all fundamentally similar to the rule of the
road or any other law which governs the behaviour of communities.
The laws of physics appear to be imposed on defenceless
Matter just as the decrees of dictators are imposed on a defenceless people. We will consider in the present chapter whether this is true.
A moment's thought should make us suspicious, for there
are differences which all would agree to be significant. Man-made laws are broken sometimes. The organic world has its
failures. But the laws of physics are never broken. It would
be meaningless to speak of failures in the inorganic world.
An electron never makes a "forbidden" transition. A particle
never fails to move with an acceleration proportional to the
force apphed to it.
Man, one might say whimsically, is less obedient than Matter.
Those who believe that the laws of physics have been imposed on the Material Universe as Acts of Parliament are imposed on a country could argue that Man breaks laws because
he possesses Free Will, but that Matter which does not possess
Free Will obeys implicitly the laws created for it. This, we
shall soon find, is not the correct explanation. But some such
view was undoubtedly entertained at one time. Whether it
is still general, is hard to say.
In universality and permanence we have a similar distinction. Laws made by legislators vary from country to country
and from year to year. The principles to which the organic
world conforms have changed with every stage in evolution.
But the laws and principles of physics never change and never
can change. Embodied in a written statement the laws of
physics, as envisaged by Jeans, would constitute a document
appropriately called the Cosmic Statute Book, a document
to which not a single word has been added and not a single
word has been taken away since the beginning of time. Those
who speak of God as the Supreme Legislator must believe
that He exercised this function once only a long, long while ago.
But are we obliged to believe in a Cosmic Statute Book?
It has been suggested to us in conversation that the question
is not a real one and would disappear if, instead of speaking of
the laws of physics we spoke of the nature of Matter. "What
are called the laws of physics", we have been told, "are really
manifestations of the nature of Matter. Physicists do not really
deal with laws but with observables. Their questions do not,
or should not, begin with 'why' but with 'how'. There is
no justification for the assumption that things which are
observed need be attributed to laws."
This view seems to be gaining ground with physicists at
the moment. Those who accept it would no longer speak of
"forbidden" transitions for an electron. They would speak
of "impossible" transitions. If Jeans accepted it he would
not say that God selected the laws of physics out of innumerable
alternatives. He would say, instead, that God selected the
nature of Matter out of innumerable alternatives.
We, however, do not have to decide whether this view is
correct or not. Whether physicists ought to ask "why" or
"how" is a question, of the procedure and the obligations of
physicists, not a question of scientific fact. It is hair-splitting
to argue whether the laws of physics are defined by the nature
of Matter or the nature of Matter is defined by the laws which
it obeys. Our question remains, whichever method of procedure or way of expressing their conclusions physicists prefer to adopt.
Consider an illustration. So long as the behaviour of an
electron in the atom. is expressed by saying that a law forbids
certain transitions, we ask: "Is this law a specified selection
between alternatives?" But if the behaviour of the electron
is expressed, instead, by saying that the nature of Matter renders
certain transitions impossible we formulate our question: "Is
the nature of Matter a specified selection between alternatives?" It is still exactly the same question. To believe that
the question does not intrude if "impossible" is substituted
for "forbidden" is to adopt the policy of the ostrich. It is to
believe that one can dispose of a problem by juggling with
The reader may, if he choose, substitute the word "observable" whenever we say "law," making such further
verbal alterations as may be necessary. The sense will remain
the same. He must not try to persuade himself that such
verbal changes have any scientific or philosophical significance. It is true that the question whether we are obliged to
believe in a Cosmic Statute Book will disappear, but only to
turn up again in another form. The proper document for a
collection of data such as might be called "observables" is a
specification. So our question then takes the form: "Are we
obliged to believe in a Cosmic Specification?"
We shall ask this question anyhow later on. But we prefer
to adhere to the traditional language of physicists in which
laws are distinguished from other data and to divide our
investigation accordingly, treating our question concerning a
Cosmic Statute Book, as part only of the more general question concerning a Cosmic Specification.
In spite of what Jeans has said we believe that most physicists
are sceptical to-day of any theory of the Material Universe
which implies that there has been a specified selection between
alternatives. But they were not always sceptical.
A few centuries ago no one would have doubted that the
laws of physics were of the governmental type. Up to the
time when science had begun to free itself from the bondage
of medieval superstition scientists still regarded God literally
as the Divine Legislator and they believed that each and every
physical law was obeyed by the Material Universe in the same
way as Acts of Parliament are obeyed by the citizens of a
country. In those days men might, without appearing unduly
fanciful, have spoken of the Cosmic Statute Book. The task
of science which was called by some a pious duty, by others
an impious impertinence, appeared to be to discover from a
study of the laws of physics and chemistry how the Creator's
In those days scientists' questions began with "how".
They did not begin with "why". For it was taken for granted
that to the question "why" only one answer could be given,
namely Divine Guidance.
By abolishing a geocentric Universe, Copernicus's discovery
of the solar system helped towards the emancipation of science.
The change in outlook which followed was considerable and
its importance is well known. But we must not forget that
this change was only in the way men regarded the position
of the earth in the scheme of things. Copernicus did not
bring about any change whatever in the way men regarded
the nature of physical laws. These were still thought of as if
they were of the governmental type. A few generations had
to pass before scientists came to suspect that in physics the
word "law" has a different meaning.
When Copernicus's measurements of planetary paths, undertaken with comparatively crude means, led him to conclude
that these paths were circles, he and those progressive contemporaries who accepted the Copernican system had no
doubt but that they were being permitted to read in the skies
proof that the Divine Will demands order and symmetry of
celestial bodies. The only explanation for the supposed law
that planets shall move in circles which was conceivable at
that time was that this law represented God's selection of the
most suitable path for such sublime heavenly bodies as planets.
It seemed only fitting that this path should be the most perfect and symmetrical figure known to geometry.
The subsequent discovery of Kepler that the paths of planets
are ellipses and not circles could not alter this survival from
the medieval outlook. It merely suggested that the Divine
Will had been previously misunderstood. The Creator's
direct control, in the capacity of Legislator, could still be
thought the cause of the planetary paths. It would not have
occurred to anyone to seek another explanation. It seemed
only necessary to find a justification for a geometrical figure
less perfect than the circle. Kepler attempted a compromise
by turning his attention from the shape of the planets' paths to
their distances from the sun. By an elaborate theory he
attempted to show that these distances bore the same proportions to each other as do those intervals in music which give
the most perfect harmony. In those days the laws of physics
were considered literally to make for order in the Material
Universe just as traffic regulations make for order in our streets
and biological laws make for order in every living organism.
The appropriateness of Charles Singer's phrase "reign of
Law" would not have been questioned.
Such theories were rendered untenable by Newton. He
was not content with the question: "how". He began to ask
"why". He showed that all bodies exert a pull on each other
proportional to their masses and inversely proportional to the
square of the distance between their centres of gravity. The
law expressing this relation is called the Law of Gravitation.
Newton also discovered the way in which the speed and path
of any body are influenced by the pushes and pulls exerted on
it, the connection between movement and applied force
being defined by his famous Laws of Motion. When Newton
applied these laws to the sun and planets he found that planetary orbits must inevitably be very close to ellipses. Thus
Newton disposed once for all of the theory that the smooth,
regular paths of heavenly bodies are due to a Divine Law or
even an impersonal Cosmic Principle expressing a preference
for regularity, symmetry, order or any sort of harmonious
At the same time Newton showed that the law of planetary
motion is not of the governmental type. It is not like an Act
of Parliament. For it does not restrict the choice between
alternatives. Newton proved that for the paths of planets
there are no alternatives. Other laws, namely those of gravitation and motion, preclude them. Whatever the Cosmic Statute
Book may contain, we can be sure, since Newton's discoveries,
that it says nothing about the way planets shall move. Provided the laws of gravitation and motion are ensured, observance of the law of planetary motion becomes automatic,
even though not specifically called for.
A great many other laws are automatically ensured as well.
Among these are the laws that the trajectory of a projectile
shall be a parabola, that the period of swing of a pendulum
shall be proportional to the square root of its length, that
centrifugal force shall be proportional to the product of the
radius and the square of the angular velocity. All these laws
are implied in those of motion, together with hundreds of
others. Newton showed that many laws relating to specific
circumstances are implied in fewer general ones. The many
specific laws need not be mentioned in the Cosmic Statute
Book because they can be deduced from the few general ones.
We will, therefore, call those laws of which the law of planetary motion is typical, "deducible" laws. This word will
distinguish them from the "selective" laws.
Newton is commonly said to have brought about a great
unification of science. What is meant is that the few laws
which he left in the Cosmic Statute Book apply to everything
in the Material Universe, in all places and at all times. Before
his time it had appeared that one law was imposed on planets,
another on projectiles, and yet another on pendulums. Newton
showed that the behaviour of all those things is the inevitable
result of a simple set of laws for all Matter. The behaviour of
all things in the physical world could thereafter be attributed
to the universal properties of Matter.
The unification of science achieved by Newton was, indeed,
revolutionary. To many it will have appeared irreligious.
For it attributed less direct and immediate control to the
Almighty than had been previously supposed. But to-day
physicists take this whittling away of the Cosmic Statute
Book for granted. They speak of "great sweeping laws that
gather together masses of apparently unrelated facts like fish into a net" 1
Since the days of Newton a great many more fish have been
gathered into the net. Successive discoveries make the Cosmic
Statute Book appear ever less bulky. Among laws which have
been struck out only recently are those of gravitation and
motion. For more than two centuries these corresponded to
nets in Professor Thornton's metaphor and not to fish; they
appeared as unrelated, as absolute facts; one would have had
to describe them as selective laws not as deducible ones. No
one could give any reason why there is gravitational attraction, why bodies conform to Newton's Laws of Motion. One
could only say that it was so. One could answer questions
about gravitation beginning with "how". But one could
not answer the question beginning with "why". But today these laws have been accounted for. They have been
proved to correspond to fish in the above metaphor. For
they have been gathered into a still wider net. This is spread
by Einstein's General Theory of Relativity. The Cosmic
Statute Book no longer contains the laws of gravitation and
After many successive curtailments it still appeared that
there was one law for tangible substance and that there were
others for less tangible contents of the Material Universe,
such as radiation or electricity. But further unification has
obliterated any distinctions between these varied contents and
has shown that the behaviour of all things in the physical world
can be attributed to the same laws. Among the very wide
nets is a principle called the Principle of Least Action. Eddington has pointed out2 that the law of gravitation, the laws of
mechanics, and the laws of the electro-magnetic field are all
summed up in this principle. Perhaps it spreads so wide a
net that no fish can escape. Perhaps, in other words, the whole
of the contents of the Material Universe obey this one law
and no other. If so, the Cosmic Statute Book need mention
nothing but the Principle of Least Action.
Let us change the metaphor. According to Indian mythology the world is supported by an elephant called Testi, and
the elephant stands on the back of a tortoise called Kurma.
Newton showed that the law of planetary motion and many
others are supported by the laws of gravitation and motion.
These in turn are supported by the Principle of Least Action.
We can compare this very broad generalization to the broad
back of the tortoise Kurma, and call the Principle of Least
Action a kurma law. All the laws which rest on it must then
be called testi laws.
Other names are possible. Philosophers would probably
give testi and kurma laws the names reducible and irreducible.
Above we have suggested the names deducible and governmental
or selective. Eddington has used the terms identical and transcendental. Each pair of names has its uses, for each conveys to the mind a different aspect of an interesting and significant distinction.
The words testi and kurma remind us that everyone who is
told of the Indian myth asks at once: "On what does the tortoise stand?" Similarly everyone who is told that a law A can be deduced from another more general law B asks:
"From what is law B deduced?" Physicists attempt to prove
that every law which is apparently a kurma law is really a
testi law. They have succeeded so well that there are hardly
any kurma laws left. But an end must come some time when
the process of deduction can go no further. What may we
expect to find then?
Does the Cosmic Statute Book contain one or two statements which require that the contents of the Material Universe shall behave thus and not otherwise? What is the fundamental law of nature which ensures the proper behaviour of
planets and pendulums, of magnets and rays of light?
We can only speculate on the answer. But a brilliant
suggestion of Eddington's leads to a speculation of considerable interest. He has shown that the principle of least action
might also be called the principle of greatest probability. He
infers that "the law of nature is that the actual state of the
world is that which is statistically most probable".3 This
suggestion deserves the most careful thought.
The traffic in our streets would be in the state which is
statistically most probable if there were no traffic regulations.
This is the state of an uncontrolled world, free from all selective principles, free from any restrictions. If Eddington's tentative suggestion is accepted, we can say what is to be
found in the Cosmic Statute Book. Could we refer to it to
discover how Matter is to behave, we should read but one
word: "Anyhow". In this case the only law in the Cosmic
Statute Book is the law that there shall be no laws.
This is, at the present stage of knowledge, pure speculation.
We know that the Cosmic Statute Book does not contain
much. But we cannot be sure yet that it contains nothing.
And only one positive statement in that document would
suffice to justify the view expressed by Jeans. Moreover, even
if Eddington's surmise about the nature of the laws of physics
is correct and that of Jeans is wrong, it is still necessary to
define probability with care. Scattered by the monkey of
chance on a billiard table a number of ivory balls all lie in one
plane. The conditions imposed by circumstances limit in
this instance the possible positions which the balls may occupy.
Similarly the constitution of the Material Universe may meet
other specified requirements which do not come under the
heading "laws", and which would appear not in a Cosmic
Statute Book, but in that more general document which we
have called a Cosmic Specification. But before we investigate what data this may contain we will give our attention to a comparison of the attitude of physicists towards their
science with that of biologists to theirs.
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1 Professor Thornton, quoted in World Power of December 1937, p. 271
2 Eddington, Space, Time and Gravitation, p. 149
3 ibid, p. 178.