"THE theory that a living organism meets the requirements
of a specification is so extraordinary," the biologist-philosopher
may say, "it flavours so much of mysticism that it should only
be accepted after the most rigid proof."
No doubt. So should every theory. But as a biologist he
believes this one already. So convinced is he that he does
not even argue about it. The language he uses takes the
reality of specifications for granted. The methods he adopts
could not be justified if a living organism did not meet the
requirements of a specification. And his success is sufficient
proof that the biologist's tacit assumptions are sound. What
is good enough for the biologist should, in this instance, be
good enough for the philosopher.
So we need not weary the reader with recondite scientific
facts and logic-chopping arguments. We will show him instead
that, so long as we address ourselves to the biologist, we are
preaching to the converted. Once again we will appeal from
Philip drunk to Philip sober.
Let us discuss, first the language used by biologists, then the
methods they follow and, lastly, how success proves their
methods to be sound.
Whenever a biologist speaks of damage, or repair, or
deformity, to mention three only of the many words which
illustrate our point, he implies that there is a specification.
For it is meaningless to apply these words to anything which
does not have to meet specified requirements.
Whatever may be done to the end moraine of a glacier
cannot constitute damage. But many things could conceivably
be done to St. Paul's Cathedral which would constitute damage.
The reason is obvious. Damage does not mean merely
alteration. It means alteration of such a kind that the specified
requirements are no longer met in their entirety. So, when
there are no specified requirements there can be no damage.
The end-moraine of a glacier may have any structure compatible with physical laws. Any change which is still compatible with these laws violates nothing. But the structure of
St. Paul's Cathedral must also be compatible with Sir Christopher Wren's specification. A change, though it conforms to
the laws of physics and chemistry, may still violate these
requirements. We then say that the building has been damaged.
Similarly a biologist who says of any living tissues that they
have been damaged implies thereby that some requirements
additional to those of physics and chemistry have been violated. If he did not mean this he would have no right to use
the word "damaged". He would have to say "changed".
Similarly the word "repair" cannot be defined without
reference to specified requirements. Let us attempt a definition.
To repair a thing is to change it. But every change does not
constitute repair. It must be a particular kind of change. It
might be suggested that repair constitutes change back to some
previous condition. But no, this would not be a true definition. A road was once a ploughed field. But one does not
repair a road by ploughing it up. One repairs the road by
remetalling to the Borough Engineer's specification. Repair
always means change to a damaged thing so that it may conform to specified requirements. When a biologist uses the
word he cannot mean anything else. If he did not believe
that there were specified requirements he would have no right
to use the word "repair". Again he would have to say
"change". If there were no specifications damage and repair
would amount to the same thing: mere alteration.
It is equally obvious that a biologist takes the reality of a
specification for granted when he says that most living
organisms are normal but that a few are deformed. It would
be meaningless to say that the end moraines of most glaciers
are normal but that a few are deformed, since for them any
structure is permitted compatible with the laws of physics
and chemistry. But a biologist does not think it meaningless
to say that most men are normal but that a few have the
deformity of a hunchback and a few the deformity of six
fingers on a hand. He applies the word "deformity" to such
features because he is convinced that there is a specification
which requires a straight back and five fingers.
We need not go on elucidating the obvious. Everyone has
known what we have said above all his life and we should
have had no reason to insist on its significance were it not that
the biologist often ignores it all when he turns philosopher.
Of course he may assert that someone will some day, somehow
find means of eliminating the words damage, repair and
deformity from biology. This is the old appeal to faith, hope
and charity and we, personally, are not charitable enough to
allow such vague speculations to pass either as science or
philosophy. Though Philip drunk may clamour that biologists
have no more right than geologists to speak of damage, repair
and deformity without further rigid proof, we feel sure that
Philip sober will continue to use these words and will not
worry about proofs.
We come next to the methods used in biology. What is
significant about them can best be illustrated by a little story.
Let us imagine two classrooms. In the one a professor of
inorganic chemistry and in the other a professor of bio-chemistry
are giving a demonstration. In the first room the professor
takes the second bottle from the right off the top shelf. (The
reason for mentioning these details will appear later.) It is a
tall brown bottle and contains caustic soda solution. He pours
some of the liquid from the bottle into a beaker filled with a
clear fluid. This is a solution of ammonium carbonate. A
striking change is observed. Everyone smells ammonia.
This has been liberated by the chemical reaction.
In the other classroom a more elaborate and difficult experiment is in progress. It would take us too long to give a
detailed description of it. The professor has secured some
muscles taken from frogs' legs. One of these has been
macerated, and shown to contain glucose. Another, with its
nerve still attached, is suspended in a dilute salt solution in the
presence of oxygen, and is repeatedly stimulated by a galvanic
current applied to the nerve ending. At each stimulation the
muscle contracts, and the professor proceeds to show the
gradual appearance of lactic acid in the fluid perfusing the
tissues. A chemical formula written on the blackboard shows
how lactic acid and carbon dioxide are oxidation products of
After the demonstration in each class the professor asks one
of the students what scientific law has been proved. The
student in inorganic chemistry sets the class laughing. He
says it was proved that the tall brown bottle, second from the
right on the top shelf, contained caustic soda solution. He is
reprimanded for his flippancy. But he might almost have
been able to read thoughts, for that is exactly what the experiment did prove to the professor's relief. At the moment of
pouring the professor remembered that a charwoman had
recently disarranged some of the bottles. He was not quite
sure that he had selected the right one until he smelt the
ammonia. But he does not tell this to his students. It has
nothing to do with the laws of chemistry, but is a matter of
his laboratory organization. So he explains what he wants
the class to infer from the experiment. This is that sodium
being a strong base, displaces the weaker base ammonia from
The student in the bio-chemistry class is not particularly
fortunate in his answer either. He says the demonstration
with the muscles proved that glucose oxidizes to lactic acid.
Were he in the other room he would probably be commended
for an answer like this. But it is not the answer expected in
the biology class. Consequently, the professor of bio-chemistry
replies a little testily that he would not have taken the trouble
to procure muscles from the legs of frogs to prove a simple
law of chemical reaction. He could have done that more
easily with glucose taken from a bottle. He reminds the
class that he is there to teach them biology, not chemistry.
For the purposes of a biological demonstration they must
regard chemical reactions as accepted facts not requiring verification. They should remember, he tells them, that biological
laws are not, like those of chemistry, generalizations about the
substances concerned, but about the tissues in which these substances are to be found; not generalizations about the way chemical compounds react on each other, but about the circumstances in living bodies under which these reactions take place.
This anecdote shows that the things taught by biologists
resemble the rules which govern the organization of a laboratory. These prescribe the specified place where each reagent
shall be kept, the specified occasions when the stock is to be
replenished, the specified sources from which new supplies
are to be obtained, the specified ways in which waste and
surplus materials are to be disposed of. Similarly, biology
students are told of the specified requirements met in the
organic world. They are told that there shall be glucose in
muscles, phosphorus in the brain, calcium in bones; that the
glucose shall be replenished from a stock of glycogen in the
liver and that oxygen shall be obtained via the lungs; that
waste products shall be eliminated through the appropriate
Biologists can tell us of specific requirements which govern
the heating and ventilation of an organism, which control the
timetable of its various functions, which ensure that its system
shall be ready to receive new stocks of material at the proper
moment. And they can tell us what will happen when there
is a departure from the normal. They find, for instance, that
it is fatal to prevent the skin from perspiring freely, that a
goitre may form if iodine is not in its specified place, that
absence of vitamins results in various deficiency diseases.
They find, in fact, that interference with the specification laid
down for the behaviour of living matter has consequences
analogous to those which would result in a laboratory if the
exhaust flues were not kept open when needed, if materials
were not requisitioned in time, and if the bottles were allowed
to become disarranged.
Hence much of the work of biologists is devoted to the
discovery of the specified requirements for each organism
and each type of tissue. Pioneers like Leonardo da Vinci
have pointed the way to the proper method. It is to examine
normal structure, normal processes, normal behaviour and
to draw therefrom, conclusions as to the nature of the specification. As more and more detail is discovered, this can be
transcribed more and more fully into words and drawings.
In the course of their work biologists have found some
variation from individual to individual. They conclude that
the specification for the species does not contain complete
requirements for every detail but allows some latitude, just
as the specification for a machine allows certain limits of
tolerance. These limits vary both in engineering and in
biology. The latitude allowed to the shape of a tree is, for
instance, great while that allowed to the hydrogen-ion concentration of the blood is small.
It is often of practical importance to know what departures
from the average may occur in normal individuals. So the
biologist's task is not completed when he has studied one
individual only. His method is to examine a large number
and to note carefully all variations between them. Only then
is he satisfied that he knows enough about the specification
to make predictions with confidence.
The biologist-philosopher may argue that physicists sometimes follow a similar method and he may infer from this
that physicists believe in the reality of specifications for the
inorganic world just as much as biologists do for the organic
world. We have met this suggestion and shall have to dispose
of it later. But not in the present chapter. Here we are
concerned with the methods and convictions of biologists
only, not with those of physicists.
We will therefore be content to show, in conclusion, that
the biologist's method leads to successful predictions which
would be inconceivable if there were no specifications. To
do this we will contrast the means available for predicting
the future configuration of any system of moving particles
when there is no specification with the means available when
there is one.
Though the reader may possibly still believe that some
inorganic systems (crystals, for instance) meet specified requirements, he is likely to agree that the stars forming our galaxy
are allowed to have any arrangement compatible with physical
laws. So the galaxy is a suitable example of an unspecified
The only means at the astronomer's disposal for predicting
future positions of stars in our galaxy are Newton's laws of
motion and such laws as are derivatives or modifications
thereof. The astronomer applies his knowledge of these laws
and of the present positions and motion of the bodies in our
solar system to predict future positions. His task is difficult
and laborious and requires much mathematics, but it is within
his powers. His methods enable him to foretell when the sun,
moon and earth will be in line and thus to prophesy eclipses.
So long as he is dealing with comparatively few bodies,
all chiefly acted on by one single one far more massive than
the others, like the sun and its planets, the astronomer's
method succeeds. When the system is more complicated it
All future configurations of the whole galaxy are as rigidly
determinate as those of the solar system, but no astronomer
can say what they will be at any date in the remote future.
The calculation is far too difficult. For with every change,
the forces on each star change too. The task of computing
the value and direction of each of the vast number of interacting forces from moment to moment and the effect they
produce is beyond the powers of any human mathematician.
It is not even possible to work out accurately how only three
stars of approximately equal size would behave under the
influence of their mutual gravitational attractions. All that
can be said with certainty is that, as the conditions are constantly changing, the configuration too, must be constantly
changing. The probabilities are overwhelmingly against a
recurrence of the same picture during the whole of time. It
is practically certain that any regularity of pattern which may
exist at one moment will be lost the next.
Suppose now we take the astronomer to a spot where an
acorn has been planted. We tell him that the place contains
a collection of small particles which are free to move relatively
to each other. We ask him to predict what their configuration
will be in ten years' time. He will tell us that the task is
beyond him. If we show him several such places he will say
that only one thing can be prophesied with certainty. This
is that after ten years there will be no trace of resemblance
between the configurations at each of the places.
As we all know, the astronomer will probably be wrong.
If the acorn planted in each spot lives and germinates an oak
tree will stand there after ten years, and the trees will resemble
each other most recognizably. We can, therefore, tell the
astronomer that his deductive methods are quite inappropriate to our problem; we can tell him to put away his pencil
and paper and substitute inductive reasoning based on experience with acorns. We can tell him that acorns and other
living things are not like galaxies. They are determined more
fully. We can tell him that biologists have means at their
disposal which are not available to astronomers. We can tell
him that a biologist predicts what will happen to the particles
moving in living tissues without ever troubling about Newton's
laws of motion. He bases his predictions on a knowledge of
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