1. CONVERSION OF ENERGY
LET us keep our attention for a while longer on the
material systems that I have called paths for diathesis
and of which an example is provided by the path from
the craneman's brain to the casting in our foundry. And
let us dwell in particular on a characteristic of every such
path that we shall soon find to be very relevant to our
enquiry. It is this. The path is so constructed that the
diathesis is converted at every stage from one form into
another.
It will help towards an understanding of what I mean
by conversion of diathesis if I refer for a moment to the
more familiar concept of conversion of energy. The
energy that passes through an electric power station, for
instance, appears in many different forms. It reaches the
station as energy bound chemically in coal. Portions of
this energy, gradually reduced by sundry losses, appear
successively as energy of radiation emitted by the white
hot furnace gases, as the potential energy of steam at a
pressure of some 900 pounds per square inch in the
boilers, as the kinetic energy of molecules of superheated
steam as they pass with a high velocity through the
turbines, as a torque in the turbine shaft, as a magnetic
field in the space between the rotor and the stator of the
electric generators, as kilowatt-hours passing through the
cables that take the energy to the consumers. Thus a
number of happenings in the power station that are in
appearance very different from each other all have this
in common that they reveal the passage of the same energy.
One could not view the sequence of events in the power
station in that way unless one thought of energy as a
commodity. And people have not been doing so for very
long. Indeed they did not think of energy as a commodity
in Newton's day. Nor did anyone think like that in the
days of James Watt. Men thought then that only one
commodity, namely steam, flows through a steam engine.
They did realise that the steam exercises a force on the
piston and thus causes it to move. They were right. But
yet, so long as they thought thus they had but little
understanding of the meaning of thermal efficiency.
Only when they thought in terms of another commodity
besides the steam, to which they gave the name energy,
did they begin to formulate the laws of thermo-dynamics.
Only then did they learn to get as much work out of the
coal as they could. When they had formed this new idea
of a second commodity that enters the engine along with
the steam they realised that the energy does not entirely
follow the same path as the steam.
The steam enters through the stop valve and leaves
through the exhaust. The energy too enters through the
stop valve; and most of it leaves through the exhaust.
But a not very large fraction leaves, most surprisingly to
those not familiar with the theory of heat engines, through
the engine shaft. This alone is the fraction that is useful,
and the aim of the designer is to increase it. In the
James Watt engine the useful fraction is only a few per
cent of the whole. In the best steam turbine it approaches
thirty per cent. This great improvement would never
have been brought about if engineers had continued to
think in terms of force only. It was by thinking of energy
as a commodity arid by attempting to divert as much as
possible of this commodity through the engine shaft to
the places where it could serve a useful purpose that
improvements were achieved in the design of heat
engines.
Thus does scientific progress depend as much on new
concepts as on new discoveries. One of the most valuable
things that Newton did for science was to give us the
concept of force. This is defined as rate of change of
momentum. It is also the product of mass and acceleration and is used to interpret changes in the velocity of a
body. It has been said by some philosophers that the
concept force is a highly artificial one, devised merely so
as to substitute one way of saying things by another. For
all I know these philosophers may be right. But it does
not detract from the usefulness of the concept.
When force is multiplied by distance a new concept
arises, energy. And I have known those who say that
force is an artificial concept to say that energy is the only
physical reality. Again this may be true for all I know.
But it seems rather odd that a very artificial concept
should become a very real one when multiplied by
distance. And whether or not energy be more real than
force it is perfectly true that science made as big a bound
forward after men had begun to concentrate their attention on the product of force arid distance as it made in
Newton's century after they had begun to concentrate
their attention on the produce of mass and acceleration.
It is possible that science may be making another
equally big bound forward in this century from concentrating attention on the product of energy and time. For this
product is called action and it is now known that all
physical changes occur as multiples of a certain small
and indivisible unit of action called a quantum. An
immensely increased understanding of the structure of the
world has already been gained with the help of the
concept, be it a very artificial or a very real one, that is
reached when force is multiplied both by distance and
by time.
However this reference to action was a digression and I
must resist the temptation of pursuing it further. What is
not wholly a digression is that a notion as fruitful to
science as that of treating energy as though it were a
commodity should also be such an odd one. Pedantic
minds would never have thought of anything like that.
Meticulous logicians would not have tolerated it. Had a
philosopher been consulted when scientists decided to
speak of energy as a commodity he would have advised
strongly against it. He would have brought the learning
of centuries to the proof that the proposal was absurd,
that it flouted the most elementary rules of language,
logic and common sense.
For the word commodity suggests a substance capable
of being stored in a container of some sort, capable of
flowing along some kind of channel, capable of being
divided up into small quantities or combined into large
ones. How easy it would have been for the all-too-clever
to prove that it is quite absurd to say that energy, which
can be defined as the product of force and distance,
rate of change of momentum, or the product of a mass
and half the square of a given velocity, can have such
properties. In fact few of the things that one may read
in textbooks about energy would suggest to dull minds
that it may legitimately be treated as a commodity. It is
said to be a capacity for doing work. But can a capacity
for doing anything be stored in a container, can it flow
from place to place, can it be divided up into a lot of little
capacities or combined into one big one? So one might
have asked rhetorically. And it must at first sight seem
equally unjustified to think of what may be a bending
moment as capable of flowing through space, of the
product when a mass is multiplied by half the square of
a velocity as stored in some container, of foot pounds as
flowing out of the steam and into the shaft of an engine.
Energy is said to be contained in a moving body by virtue
of its velocity, in coal by virtue of its chemical constitution, in a loaded beam by virtue of the bending
moment applied to the beam, in empty space by virtue
of the electro-static or magnetic field in the space. A strict
logician would have every reason to object to such a loose
way of speaking. He would say that this was to confuse
the container with the contents. But it is fortunate that
no such dull and pedantic objections were raised in the
early days of thermo-dynamics. For the notion of treating
energy as a commodity was a stroke of genius; and genius
defies the rules.
2. CONVERSION OF DIATHESIS
And now to return to the concept of diathesis as a
commodity. I am not concerned here with the question
whether or not it is as useful as the concept of energy as a
commodity. I doubt if it is. But I am concerned to point
out that, though it be as intangible as the energy that
passes out of the steam and into the engine shaft, diathesis
is a scientific reality. Let it suffice that it helps towards an
understanding of the Problem of Control when, on
suitable occasions, one thinks and speaks of diathesis as a
commodity. Such an occasion arises when one is considering any sort of indirect control.
A few examples will illustrate this. A pilot on the bridge
of a large vessel spins the wheel about its horizontal axis.
When he does this he is controlling the course of the
vessel. But the control is indirect. The performance of the
vessel is not under the direct control of the pilot; it is
only under the direct control of the rudder. What is under
the direct control of the pilot is the performance of the
wheel. And the nature of this is different from the
performance of the vessel. When the wheel is spun quite
a lot about its horizontal axis the vessel changes course
only slightly. And, moreover, it continues to change
course so long as the wheel is held there. The angle
through which the wheel has been rotated does not
determine the course of the ship but the rate at which the
course is changing.
In this example there is an equivalence between the
two performances. The complicated gear between the
wheel and the rudder ensures it. Consequently anyone
who was watching what happened to the wheel would
know something of what was happening to the ship.
And this equivalence can be expressed by saying that the
same diathesis is applied both to the wheel and the whole
vessel. But as the two performances that are equivalent
are also different in nature, the one being a large turning
movement of a wheel and the other a small rate of change
of direction, one must add that the diathesis has been
converted from one form to another during its passage
along the path from wheel to rudder.
There is such conversion whenever control is indirect.
In a microscope the turning of a micrometer screw is
converted into a change in the distance between the lens
and the slide. In a typewriter the tapping of keys on a
stationary keyboard is converted into the printing of
letters on a moving sheet of paper. When a song is being
broadcast the sounds that are heard as music, sounds that
are no more than a specific performance of the air under
the singer's direct control, constitute a diathesis that is
converted into other forms many times in the transmitting
and the receiving apparatus.
So it is in our foundry. The performance of the crane-
man's hands, the performance of the electric currents
that flow between the crane cabin and the crane motors,
the performance of the casting, these all differ from each
other very much. Yet they are all equivalents of each
other. A person who knew enough about the way in which
the apparatus in the control cabin is connected to the
crane motors would know what was happening to the
casting merely by watching the performance of the switches
and rheostats. He would also know it, at least in theory,
from studying a record of the electric currents that flow
in the sundry wires that connect the apparatus with the
motors.
3. DEFINITION OF A MECHANISM
A mechanism may serve for conversion of energy from
one form to another. But so may a thing that would not,
by the common use of language, be called a mechanism.
There is conversion from kinetic to potential energy
whenever a leaf is tossed by the wind, whenever water
evaporates from a puddle and rises into the air, whenever
a breaking wave fills a rock pool a little way up the shelving beach. And conversions from potential to kinetic
energy occur even more frequently. There is conversion
of energy in every change, be it an orderly or a chaotic
one.
Not so with conversion of diathesis. By definition
diathesis implies order. Its conversion can only be effected
with the help of a device designed for the purpose. And
it is usual to call such a device a mechanism. Indeed I
cannot think of any occasion for the use of a mechanism
except when it is required to convert diathesis from one
form to another. This is the use to which we put push
buttons, switches, triggers, taps, levers, and, in fact,
every mechanical device that serves any sort of purpose.
One cannot find anything that converts diathesis from
one form to another for which the word "mechanism"
would be inappropriate. Nor could one, without doing
violence to the meaning of words, apply the word to
anything that does not serve for the conversion of diathesis.
So a suitable definition of a mechanism is: A mechanism
is a device for the conversion of diathesis from one form into
another. This definition includes everything that it is
usual to call a mechanism and excludes everything that
one would not usually call by that name. I am unable to
suggest any other definition that would do the same.
Conversion, I must insist, not creation. All the
mechanisms with which we are familiar are instruments
of control, none is an originator of it; they all serve to
transmit diathesis and to convert it into other forms. But
the diathesis has to be applied to everyone of them, be it
through a lever, a trigger, a push button, a handle or any
other controlling device.
Would that those who dwell in the no-man's-land of
which I have spoken in the preface and spin their engaging
theories there could understand this. Then they would
discover that the brain, by virtue of being essentially a
mechanism, is limited to the purposes that a mechanism
can serve. That it can, for instance, be used to make a
choice effective but cannot itself exercise a choice; that
it can transmit and convert diathesis, but cannot create
it; that any device that ingenuity can contrive, no matter
how elaborate, no matter how well equipped with
thermionic valves and those appliances that are nowadays
incorporated in servo-mechanisms, that any mechanism
whatever works only when it is controlled.
Yet the dream of producing a mechanism that exercises
autonomous choice, that no man need ever control or
adjust, that dream persists. And it will persist so long as
the theme mind, life and body is studied only in the no-man's-land where, as I have said before, one word is as
good as another, where no one is prepared to make the
intellectual effort required to understand the distinction
between an instrument and an originator, between causation with control and causation without control, between
the conversion of a commodity into a different form and
the creation of the commodity., between energy and
organisation. But let me return to the true purpose
served by any and every mechanism.
The function of all man-made mechanisms is to replace a
performance that is inconvenient, if not impossible, for
human beings by one that is more convenient. To replace
the diversion of the course of a vessel weighing thousands
of tons by the spinning of a steering wheel; to replace the
writing of letters by the tapping of keys; to replace
minute adjustment to the distance between the lens and
the slide of a microscope, an adjustment for which human
fingers are too clumsy, by the turning of a micrometer
screw; to replace the manipulation of a heavy casting by
the operation of switches and rheostats. There is no limit
to the number and variety of forms into which any
diathesis may be converted by suitably designed mechanisms. The controlled performances may constitute changes
in the positions of things, in their size, their volume, their
intensity, their velocity, in any such features as colour,
texture, chemical constitution. But when the converting
mechanism is well designed the performance under the
direct control of human operators is always adapted to the
physical characteristics of human beings, to their stature,
their strength, the reach of their limbs, the number of
fingers on each of their hands. If there be a planet on
which octopuses have evolved to the stage when they use
tools and make machines we may be quite sure that these
differ from ours in the way they are operated. The controls in a motor car designed by the octopuses will be of a
different number, differently spaced, differently manipulated from those in our own cars.
4. PRIMARY DIATHESIS
What is true of the portion of the path for diathesis that
lies in our foundry between the crane cabin and the
.casting is true of every portion. It is true of the portion
that lies between the craneman's brain, where the
primary relays are, and his hands. There is repeated
conversion of diathesis from one form into another all
along this path. The performance of the muscle fibres
is the same diathesis as the performance of the switches
and rheostats, although its appearance is quite different.
It is also the same diathesis as the performance of the
casting. A person who knew enough about the way in
which the craneman's muscles are connected to his joints
would, at least in theory, know what the craneman was
doing to the apparatus under his control merely by watching the drill performed by the muscle fibres. If the fibres
were to perform a different drill the casting would move
differently. This is why the living systems that are studied
in physiology are correctly described as mechanisms.
They conform to the above definition. If they served some
purpose other than conversion of diathesis, or if they served
no purpose at all, they would not be called mechanisms.
The drill performed by the primary relays in the craneman's brain is also the same diathesis as that applied to
the casting. A person who knew enough about every
mechanism between these relays and the casting would,
at least in theory, know for each stage along the path what
the controlled performance was. He would know what
the muscle fibres were doing, what the craneman's limbs
were doing, what the switches and rheostats were doing,
what the casting was doing. All these performances
would be different if the drill performed by the primary
relays were different.
Let this drill be called a. primary diathesis.
I have already said that every path for diathesis on
which civilisation depends passes through a human brain.
At the beginning of every such path there is a primary
diathesis. Our most trivial gestures, no less than our most
important achievements, depend on the drills performed.
by primary relays. It depends on such drills what fields
are ploughed, what houses are built, what machines are
assembled, what ships cross the oceans, what meals are
cooked, what words are spoken, what books are written,
what songs are sung. A primary diathesis is a very
universal phenomenon. It is the basic form of diathesis.
All other forms are derived from it.
And in the same sense primary relays must be regarded
as the basic form of mechanism. Although one may find
the greatest conceivable variety of mechanisms ranged in
cascade along a path for diathesis, each serving the
purpose of converting diathesis from one form into
another, one must always find the same kind of mechanism
at the very beginning of the path. Primary relays are the
only devices that are absolutely indispensable. Without
these all our tools and gadgets, all our machines, all the
devices that one can think of for converting diathesis
from one form into another would be useless. For there
would be no diathesis to convert.
5. THE CONTROLLED FUNCTION IN A PRIMARY
DIATHESIS
In every diathesis one can speak of a controlled function.
And this function is different at every conversion. By
the term I mean the operation applied to a mechanism.
The controlled function may be the turning of the wheel
or a micrometer screw, the insertion of a key, the raising
of a latch, the pressing of a trigger, the drawing of a line
across a sheet of paper; there is no limit to the variety of
controlled functions that can be applied to and by suitably
constructed mechanisms. To say controlled function is
only another way of referring to the method by which
the mechanism is worked.
In a well designed path for diathesis the controlled
function is adapted everywhere to the mechanism that
has to exercise it. The controlled function in moving
the casting is adapted to the capacity of the crane motors;
the controlled function in operating the switches and
rheostats is adapted to the capacity of the craneman's
hands; the controlled function in operating his muscle
fibres is adapted to the capacity of the endplates by which
the nerves are joined to the fibres. As I have pointed out
above, the controlled function in operating motor-cars to
be driven by a race of superintelligent octopuses would be
adapted to the capacity of those many armed creatures.
It follows from this mutual adaptation that one can
draw some slender inferences about the system that
operates a given mechanism when one knows something
about that mechanism and that one can, conversely,
draw some slender inferences about the mechanism
when one knows something about the operating system.
From the weight of the objects to be moved in a foundry
one could draw some inferences about the horsepower of
the crane motors and from the horsepower one could,
conversely, draw some inferences about the weights.
From the number, arrangement and spacing of the controls
in our hypothetical octopus driven motor-cars one could
conclude a few things about the strength and structure
of the drivers, just as from observations of the octopuses
one could say, at least in very general terms, in what
ways the arrangement and spacing of the controls in their
motor-cars would differ from ours.
These considerations lead naturally to a little speculation about the controlled function in a primary diathesis.
It must be adapted to the capacity of a diathete, of an
influence without location and unable to transmit energy.
Any theory that may be formed about the construction
and method of working of a primary relay must be consistent with this fact. If more that is relevant were known
about a diathete one might be able to infer more about a
primary relay. But more is not known and so there is
little to go on for those who would like to form theories.
But at least one can say that a primary relay must work
on a principle quite unlike any with which we are
familiar. For every known mechanism is such that the
controlling device does interchange energy with it. A
facile explanation of the way control is initiated is not to
be expected. The Problem of Control cannot be attractive
to those who like easy solutions.
Perhaps the problem will never be solved. But I would
like to see an honest, determined and concerted effort
made to solve it before science confesses itself beaten.
And in this effort attention will have to be concentrated
on the sites of a primary diathesis; they are the places
where a diathete meets matter. One cannot expect to
discover anything about a primary diathesis by examining
controlled functions anywhere else.
Though the same energy that enters a power station
bound chemically as energy stored in the coal appears
later as the energy contained in steam at high pressure,
one could not find out anything about the chemistry of
coal from observing the conditions in the turbines. This
is because at each conversion energy takes on a different
form and one not determined by the form it previously
had. It is the same with diathesis. By observing the
casting in our foundry one could not infer what sort of
switches were controlling the motors. And one should
not expect to find out anything about the controlled
function in a primary diathesis from observation of any
other mechanisms except primary relays. To understand,
in other words, how mind controls matter one must
investigate the places where the control is immediate. It
is useless to investigate any other places.
This may be obvious. But it is worth mentioning
because it seems often to be overlooked. There are quite
a number of people who realise that there is a mind-body
problem and admit that they are interested in it. Yet
they seem to be impatient of any attempt to discuss the
problem in terms of control mechanisms. On mention
of the problem some of them immediately refer to
religious or ethical questions. They seem to think it is
relevant to ask how one can explain religious experience
or account for what they call "higher things". Sometimes
as I have pointed out already, their first question is how
one can account for the works of Shakespeare or some
other genius. They tend to suggest that a solution of the
problem is to be found in an intensive study of Beauty
and Goodness.
They are no less naive than those others for whom
mention of the Problem of Interaction immediately
arouses speculation, about thought transference, precognition, strange coincidences and other so-called occult
phenomena. None of these appreciate what the problem
is. They evidently do not realise that it is presented by
the most trivial observations of our everyday lives just as
much as by the work of a genius, by insignificant
experiences as much as by sublime or unusual ones; they
do not realise that this baffling interaction between a
diathete and matter occurs when someone merely raises
an a.rm in an idle gesture, takes a step forward, passes
a casual remark, lights a cigarette.
No less naive, again, are those physiologists who seem
to think that any recent and recondite discovery in their
subject may be relevant to the problem. They tell us
sometimes that the painstaking work on which they and
their colleagues in the same field are engaged is leading
slowly but surely to a solution. The work to which they
refer may, perhaps, be the energy changes during a
muscular contraction or the way in which secretions from
the endocrine glands affect the action of nerves. It is
all, they tell us, relevant. That such processes are remote
from the places where interaction occurs and cannot
possibly reveal anything about the mechanisms in which
it does occur is ignored.
Do these physiologists really believe that one can hope
to discover anything about the way primary relays work
from a study of the way muscles, nerves or glands work?
I doubt it. It is more likely, I think, that they have not
become aware of the problem. Quite, quite confident
that there are no such things as influences without
location, no such process as interaction, no mechanisms
to which the term primary relay could apply, they deny
that there is any problem to solve. And they believe that
discovery of more and more physiological mechanisms
is slowly but surely proving them right.
So let me point out, even at the risk of some repetition,
that, far from being disposed of by the existence of mechanisms, the problem is raised by their existence. It is to
discover how diathesis originates; and the purpose served
by mechanisms is for the transmission and conversion of
diathesis. To speak of a mechanism is not to deny but
to assert the reality of diathesis and, in asserting it, to
raise the problem of how it is introduced into material
systems.
6. THE FUNCTION OF TIMING
We have strayed a little from the concept controlled
function. Let us return to it. This function varies greatly
according to the nature of the controlled mechanism.
One may control the angle through which a wheel or a
micrometer screw is rotated; one may control the direction
in which a line is drawn across a sheet of paper; in a
manually operated telephone exchange control may consist in selection of the sockets into which plugs are inserted;
in a muscular effort control consists in selection of the
muscles in action together with control of the intensity
with which each complete muscle contracts. Of what does
the control consist in a primary diathesis?
In the absence of observation or experiment one has
to fall back on the principle of minimum hypothesis.
And this principle would hardly justify, I venture to
suggest, the assumption that a primary diathesis consists
in control of the angle through which something is
rotated, or of the distance to which something travels,
or of the intensity of something. It seems to me more
fruitful to explore first the hypothesis that the controlled
function in a primary diathesis is only timing and selection.
Let me explain why.
Though for a whole muscle there is control of intensity
of effort, there is none in the controlled function one stage
nearer to the source of the diathesis. As I have mentioned
already, variation in the intensity with which a muscle
exerts a force depends, not on the intensity with which
individual fibres contract, but on the number of fibres
that do so. Each fibre works on the "all-or-nothing"
principle. It either contracts to the full extent or remains
in a state of relaxation. Hence a muscle is a device for
converting control of the number of elements in action
into control of intensity of effort. It does so by acting as a
summating device.
A mechanism that acts on the "all-or-nothing" principle
alternates between only two states. In this respect it is
in the same category as a knife switch. And the controlled
function in such a mechanism, is the simplest that one
can think of. There is no gradation in it. Control of the
choice between an "open" and a "closed" condition is
simpler than control of the choice between an indefinitely
large number of alternative angular positions, an indefinitely large number of distances, an indefinitely large
number of different intensities. In the absence of any
evidence to the contrary it is, therefore, natural to assume
as a first hypothesis, that, like a muscle fibre, a primary
relay works on the "all-or-nothing" principle, that it
alternates between only two states. In the one it allows
an impulse to pass to the muscle fibre, in the other it
prevents the impulse from passing.
If this most simple of all possible assumptions is justified,
a diathete determines only the moment in time when a
change of state shall occur in any given primary relay.
The controlled function in a primary diathesis consists of
what might be aptly called pure timing.
The timing, however, demands considerable coordination. The number of muscle fibres that take part
in even a slight activity is very great. The moment when
any one of them contracts must be carefully co-ordinated
with the moments when all the others do so. Were any
of them to contract or relax out of their proper sequence
the required movement of a limb would not occur.
Chaos is avoided and order ensured because the fibres
perform a genuine drill, because of the correct timing of
their operation. If there is a separate primary relay for
each muscle fibre the timing in a primary diathesis does
not consist in the timing of one operation only but in the
coordinated timing of a great many. The diathete
selects the relays as well as the moments when they operate.
Admittedly I have met the theory that a very complicated co-ordinating mechanism, constructed on a principle
similar to that of an automatic telephone exchange, or an
automatic gear change, is interposed between the primary
relays and the muscle fibres. A specific "setting" of this
mechanism ensures, according to the theory, that the
fibres shall all contract and relax in the proper sequence,
just as a specific setting of the automatic gear change in a
motor-car ensures the correct sequence of operations. The
setting would have to be varied from moment to moment
so that it might be the correct one for every changing
movement of the limbs.
This theory has been propounded by those who seem
to believe naively that the assumption of sufficiently
elaborate mechanisms in the brain can provide an answer
to all questions about a primary diathesis. But actually
the controlled function for such an elaborate mechanism
would not be very simple; it would be very complicated
indeed. The "automatic telephone exchange" theory
certainly does not conform to the principle of minimum
hypothesis.
7. THE PROBLEM REFORMULATED
Let me therefore make the provisional assumption that
the basic diathesis, from which all others are only obtainable by conversion through suitably constructed mechanisms, is pure timing. And let me reformulate the Problem
of Control on this assumption.
The part of a primary relay under the direct control
of a diathete, is, of course, its controlled element. So our
attention must be directed to this. This element, I am
supposing, alternates between two states. When it is in
the one state an impulse passes successively through every
relay in cascade with the primary one; when it is in the
other state the impulse cannot pass.
The difference between the two states of the controlled
element is a physical difference. It can only be effected
by the movement of physical objects and this movement
can only occur if energy is transmitted to or from the
element. And the requisite quantity of energy must, as
I shall show in the next chapter, be appreciable.
The relay may be required to operate at any moment
and so the energy needed for a change of state of the
controlled element must always be available. But it is
not always effective. For it to become so the diathete
must do something; but what it does cannot be to transfer
energy. One is obliged to picture the controlled element
of a primary relay as a mechanism quite different from
any with which we are familiar. Like every other
mechanism it must receive a supply of energy so that it
shall work at all and it must receive a supply of diathesis
so that it shall work in the specified manner, the "specified
manner" meaning in this case "at the specified moment".
But unlike every other mechanism the diathesis is supplied
without any expenditure of energy. The controlled
element of a primary relay must be a mechanism in which
an uncontrolled supply of energy is rendered effective
at controlled moments of time. Fig. 4 on page 96 would
serve for the controlled element of a primary relay
if on the right hand top corner the words "operating
energy" were omitted and the word "diathesis" occurred
alone. Like the casting the controlled element of a
primary relay is supplied with two commodities, energy
and diathesis; and each has a separate source. But in the
case of a primary relay the diathesis is pure; it is not
accompanied by any energy at all. What sort of a
mechanism can this be?
Thus can one formulate the Problem of Control in
terms of a primary diathesis. The more one knows about
energy and mechanical devices the more baffling does it
appear.
For no mechanism that behaves as a primary relay
must behave has ever been observed or even thought of.
But that does not prove that such a mechanism is
physically impossible. I have little doubt that more than
one plausible theory could be found for the way a primary
relay works and I shall venture to suggest one later. But
I do not attach much importance to any theories, not
even to my own, and anyhow this is not the time for
theorising. It is the time for something more difficult,
for the asking of relevant questions. It is the time for
making an honest effort to appreciate the problem with
all its difficulties and to realise how every one of the
many theories that come so readily to the mind must be
subjected to a rigid criticism. And this applies, let me add,
not only to theories about non-material influences and
the way they work, but also to such theories that there is
no such thing as teleology, that it is in the nature of matter
to plan for the future, that in some mystical way the
"Gestalt" doctrine provides a solution, that it is unscientific to distinguish between controlled causes and
uncontrolled causes, that the initiation of control is not a
proper subject for scientific enquiry. The need for
criticism exists not only for those theories that purport to
explain the Problem of Interaction but also for those that
purport to explain it away.
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