k. r. popper: of clouds and clocks

8/13/2019 K. R. Popper: Of Clouds and Clocks

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Of Clouds and Clocks

AN APPROACH TO THE PROBLEM OF RATIONALITY AND THE FREEDOM OF MAN

Karl Popper

Objective Knowledge: An Evolutionary Approach

My predecessor who in this hall gave the first Arthur Holly Compton Memorial Lecture ayear ago was more fortunate than I. He knew Arthur Compton personally; I never methim.

But I have known of Compton since my student days in the nineteentwenties! andespecially since "#$% when the famous e&periment of Compton and 'imone refuted the(eautiful (ut shortlived )uantum theory of Bohr! *ramers! and 'later.+ ,his refutationwas one of the decisive events in the history of )uantum theory! for from the crisis

which it created there emerged the socalled -new )uantum theorythe theories ofBorn and Heisen(erg! of 'chrodinger! and of /irac.

It was the second time that Comptons e&perimental tests had played a crucial role inthe history of )uantum theory. ,he first time had (een! of course! the discovery of theCompton effect! the first independent test 0as Compton himself pointed out1 of2insteins theory of light )uanta or photons.

3ears later! during the 'econd 4orld 4ar! I found to my surprise and pleasure thatCompton was not only a great physicist (ut also a genuine and courageousphilosopher; and further! that his philosophical interests and aims coincided with myown on some important points. I found this when! almost (y accident! I got hold ofComptons fascinating ,erry Lectures which he had pu(lished in "#+% in a (ook entitled

,he 5reedom of Man.

3ou will have noticed that I have incorporated the title of Comptons (ook! ,he 5reedomof Man! into my own title today. I have done so in order to stress the fact that mylecture will (e closely connected with this (ook of Comptons. More precisely! I intendto discuss the same pro(lems which Compton. discussed in the first two chapters ofthis (ook! and again in the second chapter of another of his (ooks! ,he HumanMeaning of 'cience.

In order to avoid misunderstandings I must stress! however! that my lecture today isnot mainly a(out Comptons (ooks. It is rather an attempt to look afresh at the sameancient philosophical pro(lems with which he grappled in these two (ooks! and an

attempt to find a new solution to these ancient pro(lems. ,he sketchy and! verytentative solution I am going to outline here seems to me to fit in well with Comptonsmain aims! and I hopeindeed I (elievethat he would have approved of it.

II

,H2 central purpose of my lecture is to try to put these ancient pro(lems simply andforcefully (efore you. But first I must say something a(out the clouds and clocks whichappear in the title of my lecture.


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My clouds are intended to represent physical. systems which! like gases! are highlyirregular! disorderly! and more or less unpredicta(le. I shall assume that we have(efore us a schema or arrangement in which a very distur(ed or disorderly cloud isplaced on the left. 6n the other e&treme of our arrangement! on its right! we may placea very relia(le pendulum clock! a precision clock! intended to represent physicalsystems which are regular! orderly! and highly predicta(le in their (ehaviour.

According to what I may call the commonsense view of things! some naturalphenomena! such as the weather! or the coming and going of clouds! are hard topredict7 we speak of the -vagaries of the weather. 6n the other hand! we speak of-clockwork precision if we wish to descri(e a highly regular and predicta(lephenomenon.

,here are lots of things! natural processes and natural phenomena! which we mayplace (etween these two e&tremesthe clouds on the left! and the clocks on the right.

,he changing seasons are somewhat unrelia(le clocks! and may therefore (e putsomewhere towards the right! though not too far. I suppose we shall easily agree to putanimals not too far from the clouds on the left! and plants somewhat nearer to theclocks. Among the animals! a young puppy will have to (e placed further to the left

than an old dog. Motor cars! too! will find their place somewhere in our arrangement!according to their relia(ility7 a Cadillac! I suppose! is pretty far over to the right! andeven more so a 8olls8oyce! which will (e )uite close to the (est of the clocks. 9erhapsfurthest to the right should (e placed the solar system:

As a typical and interesting e&ample of a cloud I shall make some use here of a cloudor cluster of small flies or gnats. Like the individual molecules in a gas! the individualgnats which together form a cluster of gnats move in an. astonishingly irregular way. Itis almost impossi(le to follow the flight of any one individual gnat! even though each ofthem may (e )uite (ig enough to (e clearly visi(le.

Apart from the fact that the velocities of the gnats do not show a very wide spread! the

gnats present us with an e&cellent picture of the irregular movement of molecules in agas cloud! or of the minute drops of water in a storm cloud. ,here are! of course!differences. ,he cluster does not dissolve or diffuse! (ut it keeps together fairly well.

,his is surprising! considering the disorderly character of the movement of the variousgnats; (ut it has its analogue in a sufficiently (ig gas cloud 0such as our atmosphere! orthe sun1 which is kept together (y gravitational forces. In the case of the gnats! theirkeeping together can (e easily e&plained if we assume that! although they fly )uiteirregularly in all directions! those that find that they are getting away from the crowdturn (ack towards that part which is densest.

,his assumption e&plains how the cluster keeps together even though it has no leader!and no structureonly a random statistical distri(ution resulting from the fact that eachgnat does e&actly what he likes! in a lawless or! random manner! together with the fact

that he does not like to stray too far from his comrades.

I think that a philosophical gnat might claim that the gnat society is a great society orat least a good society! since it is the most egalitarian! free! and democratic societyimagina(le.

However! as the author of a (ook on ,he 6pen 'ociety! I would deny that the gnatsociety is an open society. 5or I take it to (e one of the characteristics of an opensociety that it cherishes! apart from a democratic form of government! the freedom ofassociation! and that it protects and even encourages the formation of free su(


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societies! each holding different opinions and (eliefs. But every reasona(le gnat wouldhave to admit that in his society this kind of pluralism is lacking.

I do not intend! however! to discuss today any of the social or political issues connectedwith the pro(lem of freedom; and I intend to use the cluster of gnats not as an e&ampleof a social system! (ut rather as my main illustration of a cloudlike physical system! asan e&ample or paradigm of a highly irregular or disordered cloud.

Like many physical! (iological! and social systems! the cluster of gnats may (edescri(ed as a whole. 6ur conecture that it is kept together (y a kind of attractionwhich its densest part e&erts on individual gnats straying too far from the crowd showsthat there is even a kind of action or control which this whole e&erts upon its elementsor parts.


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works! while we do not have any knowledge a(out the detailed interaction of theparticles that form a gas cloud! or an organism. And he will assert that! once we haveo(tained this knowledge! we shall find that gas clouds or organisms are as clocklike asour solar system.


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are a(out on a par with an upholsterers measurements of carpets and curtains . . ..5rom this 9eirce concluded that we were free to conecture that there was a certainlooseness or imperfection in all clocks! and that this allowed an element of chance toenter. ,hus 9eirce conectured that the world was not only ruled (y the strict


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the new )uantum theory for rescuing him from this difficult intellectual situation. ,hushe writes! in ,he 5reedom of Man7 -,he physicist has rarely ... (othered himself withthe fact that if ... completely deterministic ... laws ... apply to mans actions! he ishimself an automaton. And in he Human Meaning of 'cience he e&presses his relief7

In my own thinking on this vital su(ect I am thus in a much more satisfied state ofmind than I could have (een at any earlier stage of science. If the statements of the

laws of physics were assumed correct! one would have had to suppose 0as did mostphilosophers1 that the feeling of freedom is illusory! or if free choice were consideredeffective! that the statements of the laws of physics were ... unrelia(le. ,he dilemmahas (een an uncomforta(le one .. .

Later in the same (ook Compton sums up the situation crisply in the words7 -... it is nolonger ustifia(le to use physical law as evidence against human freedom.$

,hese )uotations from Compton show clearly that (efore Heisen(erg he had (eenharassed (y what I have here called the nightmare of the physical determinist! and thathe had tried to escape from this nightmare (y adopting something like an intellectualsplit personality. 6r as he himself puts it7 -4e physicists have preferred merely to payno attention to the difficulties.. .

Compton welcomed the new theory which rescued him from all this. I (elieve that theonly form of the pro(lem of determinism which is worth discussing seriously is e&actlythat pro(lem which worried Compton7 the pro(lem which arises from a physical theorywhich descri(es the world as a physically complete or a physically closed system. By aphysically closed system I mean a set or system of physical entities! such as atoms orelementary particles or physical forces or fields of forces! which interact with eachother and only with each other in accordance with definite laws of interaction that donot leave any room for interaction with! or interference (y! anything outside thatclosed set or system of physical entities. It is this -closure of the system that createsthe deterministic nightmare.

>III

I 'H6FL/ like to digress here for a minute in order to contrast the pro(lem of physicaldeterminism! which I consider to (e of fundamental importance! with the far fromserious pro(lem which many philosophers and psychologists! following Hume! havesu(stituted for it. .

Hume interpreted determinism 0which he called -the doctrine of necessity! or -thedoctrine of constant conunction1 as the doctrine that -like causes always produce likeeffects and that -like effects necessarily follow from like causes.+ Concerning humanactions and volitions he held! more particularly! that -a spectator can commonly inferour actions from our motives and character; and even where he cannot! he concludes

in general! that he might! were he perfectly ac)uainted with every circumstance of oursituation and temper! and the most secret springs of our . . . disposition.


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-2very event has a cause! is so vague that it is perfectly compati(le with physicalindeterminism.

Indeterminismor more precisely! physical indeterminismis merely the doctrine thatnot all events in the physical world are predetermined with a(solute precision! in alltheir infinitesimal details. Apart from this! it is compati(le with practically any degree ofregularity you like! and it does not! therefore! entail the view that there are -events

without causes; simply (ecause the terms -event and -cause are vague enough tomake the doctrine that every event has a cause compati(le with physicalindeterminism. 4hile physical determinism demands complete and infinitely precisephysical predetermination and the a(sence of any e&ception whatever! physicalindeterminism asserts no more than that determinism is false! and that there are atleast some e&ceptions! here or there! to precise predetermination.

,hus even the formula -2very o(serva(le or measura(le physical event has ano(serva(le or measura(le physical cause is still compati(le with physicalindeterminism! simply (ecause no measurement can (e infinitely precise7 for thesalient point a(out physical determinism is that! (ased on


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ignorance! so that! should we (e fully informed a(out the system! any appearance oflooseness would disappear. 9sychology! on the other hand! never had this character.

9hysical determinism! we might say in retrospect! was a daydream of omnisciencewhich seemed to (ecome more real with every advance in physics until it (ecame anapparently inescapa(le nightmare. But the corresponding daydreams of thepsychologists were never more than castles in the air7 they were Ftopian dreams of

attaining e)uality with physics! its mathematical methods! and its powerfulapplications; and perhaps even of attaining superiority! (y moulding men and societies.04hile these totalitarian dreams are not serious from a scientific point of view! they arevery dangerous politically; (ut since I have dealt with these dangers elsewhere I do notpropose to discuss the pro(lem here.1

IJ

I HA>2 called physical determinism a nightmare. It is a nightmare (ecause it assertsthat the whole world with everything in it is a huge automaton! and that we are nothing(ut little cogwheels! or at (est su(automata! within it.

It thus destroys! in particular! the idea of creativity. It reduces to a complete illusion theidea that in preparing this lecture I have used my (rain to create something new. ,herewas no more in it! according to physical determinism! than that certain parts of my(ody put down (lack marks on white paper7 any physicist with sufficient detailedinformation could have written my lecture (y the simple method of predicting theprecise places on which the physical system consisting of my (ody 0including my (rain!of course! and my fingers1 and my pen would put down those (lack marks. 6r to use amore impressive e&ample7 if physical determinism is right! then a physicist who iscompletely deaf and who has never heard any music could write all the symphoniesand concertos written (y Moart or Beethoven! (y the simple method of studying theprecise physical states of their (odies and predicting where they would put down (lackmarks on their lined paper. And our deaf physicist could do even more7 (y studying

Moarts or Beethovens (odies with sufficient care he could write scores which werenever actually written (y Moart or Beethoven! (ut which they would have written hadcertain e&ternal circumstances of their lives (een different7 if they had eaten lam(! say!instead of chicken! or drunk tea instead of coffee.

All this could (e done (y our deaf physicist if supplied with a sufficient knowledge ofpurely physical conditions. ,here would (e no need for him to know anything a(out thetheory of musicthough he might (e a(le to predict what answers Moart or Beethovenwould have written down under e&amination conditions if presented with )uestions onthe theory of counterpoint.

I (elieve that all this is a(surd; and its a(surdity (ecomes even more o(vious! I think!when we apply this method of physical prediction to a determinist.

5or according to determinism! any theoriessuch as! say! determinismare held (ecauseof a certain physical structure of the holder 0perhaps of his (rain1. Accordingly we aredeceiving ourselves 0and are physically so determined as to deceive ourselves1whenever we (elieve that there are such things as arguments or reasons which makeus accept determinism.

6r in other words! physical determinism is a theory which! if it is true! is not argua(le!since it must e&plain all our reactions! including what appear to us as (eliefs (ased onarguments! as due to. purely physical conditions. 9urely physical conditions! including


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our physical environment! make us say or accept whatever we say or accept; and awelltrained physicist who does not know any-5rench! and who has never heard ofdeterminism! would (e a(le to predict what a 5rench determinist would say in a 5renchdiscussion on determinism; and of course also what his indeterminist opponent wouldsay. But this means that if we (elieve that we have accepted a theory like determinism(ecause we were swayed (y the logical force of certain arguments! then we aredeceiving ourselves! according to physical determinism; or more precisely! we are in a

physical condition which determines us to deceive ourselves.

Hume saw much of this! even though it appears that he did not )uite see what it meantfor his own arguments; for he confined himself to comparing the determinism of -our

udgements with that of -our actions! saying that -ee have no more li(erty in the onethan in the other.

Considerations such as these may perhaps (e the reason why there are so manyphilosophers who refuse to take the pro(lem of physical determinism seriously anddismiss it as a (ogy.+ 3et the doctrine that man is a machine was argued mostforcefully and seriously in "%"! long (efore the theory of evolution (ecame generallyaccepted! (y de Lamettrie; and the theory of evolution gave the pro(lem an evensharper edge! (y suggesting that there may (e no clear distinction (etween living

matter and dead matter.+@ And in spite of the victory of the new )uantum theory! andthe conversion of so many physicists to indeterminism! de Lamettries doctrine thatman is a machine has today perhaps more defenders than ever (efore amongphysicists! (iologists! and philosophers; especially in the form of the thesis that man isa computer.

5or if we accept a theory of evolution 0such as /arwins1 then even if we remainsceptical a(out the theory that life emerged from inorganic matter we can hardly denythat there must have (een a time when a(stract and. nonphysical entities! such asreasons and arguments and scientific knowledge! and a(stract rules! such as rules for(uilding railways or (ulldoers or sputniks or! say! rules of grammar or of counterpoint!did not e&ist! or at any rate had no effect upon the physical universe. It is difficult to

understand how the physical universe could produce a(stract entities such as rules!and then could come under the influence of these rules! so that these rules in their turncould e&ert very palpa(le effects upon the physical universe.

,here is! however! at least one perhaps somewhat evasive (ut at any rate easy wayout of this difficulty. 4e can simply deny that these a(stract entities e&ist and that theycan influence the physical universe. And we can assert that what do e&ist are our(rains! and that these are machines like computers; that the allegedly a(stract rulesare physical entities! e&actly like the concrete physical punchcards (y which we-programme our computers; and that the e&istence of anything nonphysical is ust-an illusion! perhaps! and at any rate unimportant! since everything would go on as itdoes even if there were no such illusions.

According to this way out! we need not worry a(out the -mental status of theseillusions. ,hey may (e universal properties of all things7 the stone which I throw mayhave the illusion that it umps! ust as I have the illusion that I throw it; and my pen! ormy computer! may have the illusion that it works (ecause of its interest in thepro(lems which it thinks that it is solvingand which I think that I am solvingwhile infact there is nothing of any significance going on e&cept purely physical interactions.

3ou may see from all this that the pro(lem of physical determinism which worriedCompton is indeed a serious pro(lem. It is not ust a philosophical pule! (ut it affectsat least physicists! (iologists! (ehaviourists! psychologists! and computer engineers.


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Admittedly! )uite a few philosophers have tried to show 0following Hume or 'chlick1that it is merely a ver(al pule! a pule a(out the use of the word freedom. Butthese philosophers have hardly seen the difference (etween the pro(lem of physicaldeterminism and that of philosophical determinism; and they are either deterministslike Hume! which e&plains why for them -freedom is -ust a word! or they have neverhad that close contact with the physical sciences or with computer engineering which

would have impressed upon them that we are faced with more than a merely ver(alpule.

J

LI*2 Compton I am among those who take the pro(lem of physical determinismseriously! and like Compton I do not (elieve that we are mere computing machines0though I readily admit that we can learn a great deal from computing machines evena(out ourselves1. ,hus! like Compton! I am a physical indeterminist7 physicalindeterminism! I (elieve! is a necessary prere)uisite for any solution of our pro(lem.4e have to (e indeterminists; yet I shall try to show that indeterminism is not enough.

4ith this statement! indeterminism is not enough! I have arrived! not merely at a newpoint! (ut at the very heart of my pro(lem.

,he pro(lem may (e e&plained as follows.

If determinism is true! then the whole world is a perfectly running flawless clock!including all clouds! all organisms! all animals! and all men. If! on the other hand!9eirces or Heisen(ergs or some other form of indeterminism is true! then sheerchance plays a maor role in our physical world. But is chance really more satisfactorythan determinism:

,he )uestion is well known. /eterminists like 'chlick have put it in this way7 ...

freedom of action! responsi(ility! and mental sanity! cannot reach (eyond the realm ofcausality7 they D. 6f Clouds and Clocks $$ stop where chance (egins.... a higherdegree of randomness ... simply means a higher degree of irresponsi(ility.

I may perhaps put this idea of 'chlicks in terms of an e&ample I have used (efore7 tosay that the (lack marks made on white paper which I produced in preparation for thislecture were ust the result of chance is hardly more satisfactorythan to say that theywere physically predetermined. In fact! it is even less satisfactory. 5or some peoplemay perhaps (e )uite ready to (elieve that the te&t of my lecture can (e in principlecompletely e&plained (y my physical heredity! and my physical environment! includingmy up(ringing! the (ooks I have (een reading! and the talks I have listened to; (uthardly any(ody will (elieve that what I am reading to you is the result of nothing (utchance ust a random sample of 2nglish words! or perhaps of letters! put together

without any purpose! deli(eration! plan! or intention.

,he idea that the only alternative to determinism is ust sheer chance was taken over(y 'chlick! together with many of his views on the su(ect! from Hume! who assertedthat -the removal of what he called -physical necessity must always result in -thesame thing with chance. As o(ects must either (e conoind or not! . . . tis impossi(leto admit of any medium (etwi&t chance and an a(solute necessity.

I shall later argue against this important doctrine according to which the onlyalternative to determinism is sheer chance. 3et I must admit that the doctrine seems to


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hold good for the )uantumtheoretical models which have (een designed to e&plain! orat least to illustrate! the possi(ility of human freedom. ,his seems to (e the reasonwhy these models are so very unsatisfactory.

Compton himself designed such a model! though he did not particularly like it. It uses)uantum indeterminacy! and the unpredicta(ility of a )uantum ump! as a model of ahuman decision of great moment. It consists of an amplifier which amplifies the effect

of a single )uantum ump in such a way that it may either cause an e&plosion ordestroy the relay necessary for (ringing the e&plosion a(out. In this way one single)uantum ump may (e e)uivalent to a maor decision. But in my opinion the model hasno similarity to any rational decision. It is! rather! a model of akind of decisionmakingwhere people who cannot make up their minds say7 Let us toss a penny. In fact! thewhole apparatus for amplifying a )uantum ump seems rather unnecessary7 tossing apenny! and deciding on the result of the toss whether or not to pull a trigger! would do

ust as well. And there are of course computers with (uiltin pennytossing devices forproducing random results! where such are needed.

It may perhaps (e said that some of our decisions are like pennytosses7 they are snapdecisions! taken without deli(eration! since we often do not have enough time todeli(erate. A driver or a pilot has sometimes to take a snapdecision like this; and if he

is well trained! or ust lucky! the result may (e satisfactory; otherwise not.

I admit that the )uantum ump model may (e a model for such snapdecisions; and Ieven admit that it is conceiva(le that something like the amplification of a )uantum

ump may actually happen in our (rains if we make a snapdecision. But are snapdecisions really so very interesting: Are they characteristic of human (ehaviourofrational human (ehaviour:

I do not think so; and I do not think that we shall get much further with )uantumumps. ,hey are ust the kind of e&amples which seem to lend support to the thesis ofHume and 'chlick that perfect chance is the only alternative to perfect determinism.4hat we need for understanding rational human (ehaviour and indeed! animal

(ehaviouris something intermediate in character (etween perfect chance and perfectdeterminismsomething intermediate (etween perfect clouds and perfect clocks.

Humes and 'chlicks ontological thesis that there cannot e&ist anything intermediate(etween chance and determinism seems to me not only highly dogmatic 0not to saydoctrinaire1 (ut clearly a(surd; and it is understanda(le only on the assumption thatthey (elieved in a complete determinism in which chance has no status e&cept as asymptom of our ignorance. 0But even then it seems to me a(surd! for there is! clearly!something like partial knowledge! or partial ignorance.1 5or we know that even highlyrelia(le clocks are not really perfect! and 'chlick 0if not Hume1 must have known thatthis is largely due to factors such as frictionthat is to say! to statistical or chanceeffects. And we also know that our clouds are not perfectly chancelike! since we canoften predict the weather )uite successfully! at least for short periods.

JI

,HF' we shall have to return to our old arrangement with clouds on the left and clockson the right and animals and men somewhere in (etween. But even after we havedone so 0and there are some pro(lems to (e solved (efore we can say that thisarrangement is in keeping with presentday physics1! even then we have at (est onlymade room for our main )uestion.


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5or o(viously what we want is to understand how such nonphysical things as purposes!deli(erations! plans! decisions! theories! intentions! and values! can play a part in(ringing a(out physical changes in the physical world. ,hat they do this seems to (eo(vious! pace Hume and Laplace and'chlick. It is clearly untrue that all thosetremendous physical changes (rought a(out hourly (y our pens! or pencils! or(ulldoers! can (e e&plained in purely physical terms! either (y a deterministic physicaltheory! or 0(y a stochastic theory1 as due to chance.

Compton was well aware of this pro(lem! as the following charming passage from his,erry Lectures shows7 It was some time ago when I wrote to the secretary of 3aleFniversity agreeing to give a lecture on


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8etaining Comptons own (ehaviourist terminology! Comptons pro(lem may (edescri(ed as the pro(lem of the influence of the universe of a(stract meanings uponhuman (ehaviour 0and there(y upon the physical universe1. Here universe ofmeanings is a shorthand term comprising such diverse things as promises! aims! andvarious kinds of rules! such as rules of grammar! or of polite (ehaviour! or of logic! or ofchess! or of counterpoint; also such things as scientific pu(lications 0and other

pu(lications1 ; appeals to our sense of ustice or generosity; or to our artisticappreciation; and so on! almost ad infinitum.

I (elieve that what I have here called Comptons pro(lem is one of the most interestingpro(lems of philosophy! even though few philosophers have seen it. In my opinion it isa real key pro(lem! and more important than the classical (odymind pro(lem which Iam calling here /escartess pro(lem.

In order to avoid misunderstandings I may perhaps mention that (y formulating hispro(lem in (ehaviouristic terms! Compton certainly had no intention of su(scri(ing to afullfledged (ehaviourism. 6n the contrary! he did not dou(t either the e&istence of hisown mind! or that of other minds! or of e&periences such as volitions! or deli(erations!or pleasure! or pain. He would therefore have insisted that there is a second pro(lem to

(e solved.

4e may identify this second pro(lem with the classical (odymind pro(lem! or/escartess pro(lem. It may (e formulated as follows7 how can it (e that such things asstates of mindvolitions! feelings! e&pectationsinfluence or control the physicalmovements of our lim(s: And 0though this is less important in our conte&t1 how can it(e that the physical states of an organism may influence its mental states:

Compton suggests that any satisfactory or accepta(le solution of either of these twopro(lems would have to comply with the following postulate which I shall callComptons postulate of freedom7 the solution must e&plain freedom; and it must alsoe&plain how freedom is not ust chance (ut! rather! the result of a su(tle interplay

(etween something almost random or haphaard! and something like a restrictive orselective controlsuch as an aim or a standard though certainly not a castiron control.5or it is clear that the controls which guided Compton (ack from Italy allowed himplenty of freedom7 freedom! say! to choose (etween an American and a 5rench orItalian (oat; or freedom to postpone his lecture! had some more important o(ligationarisen.

4e may say that Comptons postulate of freedom restricts the accepta(le solutions ofour two pro(lems (y demanding that they should conform to the idea of com(iningfreedom and control! and also to the idea of a plastic control! as I shall call it incontradistinction to a castiron control.

Comptons postulate is a restriction which I accept gladly and freely; and my own free

and deli(erate though not uncritical acceptance of this restriction may (e taken as anillustration of that com(ination of freedom and control which is the very content ofComptons postulate of freedom.

JIII

I HA>2 e&plained our two central pro(lems Comptons pro(lem and /escartesspro(lem. In order to solve them we need! I (elieve! a new theory; in fact! a new theoryof evolution! and a new model of the organism.


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,his need arises (ecause the e&isting indeterministic theories are unsatisfactory. ,heyare indeterministic; (ut we know that indeterminism is not enough! and it is not clearhow they escape from 'chlicks o(ection! or whether they conform to Comptonspostulate of freedom plus control. Again! Comptons pro(lem is )uite (eyond them7they are hardly relevant to it. And although these theories are attempts to solve/escartess pro(lem! the solutions they propose do not appear to (e satisfactory.

,he theories I am alluding to may (e called masterswitch models of control or! more(riefly! masterswitch theories. ,heir underlying idea is that our (ody is a kind ofmachine which can (e regulated (y a lever or switch from one or more central controlpoints. /escartes even went so far as to locate the control point precisely7 it is in thepineal gland! he said! that mind acts upon (ody. 'ome )uantum theorists suggested0and D. 6f Clouds and Clocks $++ Compton very tentatively accepted the suggestion1that our minds work upon our (odies (y influencing or selecting some )uantum umps.

,hese are then amplified (y our central nervous system which acts like an electronicamplifier7 the amplified )uantum umps operate a cascade of relays or masterswitchesand ultimately effect muscular contractions. ,here are! I think! some indications inComptons (ooks that he did not much like this particular theory or model! and that heused it for one purpose only7 to show that human indeterminism 0or even -freedom1

does not necessarily contradict )uantum physics. I think he was right in all this!including his dislike of masterswitch theories.

5or these masterswitch theorieswhether the one of /escartes! or the amplifiertheories of the )uantum physicists(elong to what I may perhaps call tiny (a(ytheories. ,hey seem to me to (e almost as unattractive as tiny (a(ies.

I am sure you all know the story of the unmarried mother who pleaded7 But it is only avery tiny one. /escartess pleading seems to me similar7 -But it is such a tiny one7 it isonly an une&tended mathematical point in which our mind may act upon our (ody.

,he )uantum theorists hold a very similar tiny (a(y theory7 -But it is only with one

)uantum ump! and ust within the Heisen(erg uncertaintiesand these are very tinyindeedthat a mind can act upon a physical system. I admit that there is perhaps aslight advance here! in so far as the sie of the (a(y is specified. But I still do not lovethe (a(y.

5or however tiny the masterswitch may (e! the masterswitch cumamplifier modelstrongly suggests that all our decisions are either snapdecisions 0as I have called themin section & a(ove1 or else composed of snapdecisions.


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new theory some mechanism of trial and errorelimination.

I shall now outline how I intend to proceed.

Before formulating my evolutionary theory in general terms I shall first show how itworks in a particular case! (y applying it to our first pro(lem! that is! to Comptonspro(lem of the influence of meaning upon (ehaviour.

After having in this way solved. Comptons pro(lem! I shall formulate the theory in ageneral way. ,hen it will (e found that it also containswithin the framework of our new!theory which creates a new pro(lemsituation a straightforward and almost trivialanswer to /escartes s classical (odymind pro(lem.

JI>

L2, us now approach our first pro(lemthat is! Comptons pro(lem of the influence ofmeaning upon (ehaviour(y way of some comments on the evolution of languagesfrom animal languages to human languages.

Animal languages and human languages have many things in common! (ut there arealso differences7 as we all know! human languages do somehow transcend animallanguages. Fsing and e&tending some ideas of my late teacher *arl BuhlerG I shalldistinguish two functions which animal and human languages share! and two functionswhich human language alone possesses; or in other words! two lower functions! andtwo higher ones which evolved on the (asis of the lower functions.

,he two lower functions of language are these. 5irst! language! like all other forms of(ehaviour! consists of symptoms or e&pressions; it is symptomatic or e&pressive of thestate of the organism which makes the linguistic signs. 5ollowing Buhler! I call this thesymptomatic or e&pressive function of language.

'econdly! for language or communication to take place! there must not only (e a signmaking organism or a sender! (ut also a reacting one! a receiver. ,he symptomatice&pression of the first organism! the sender! releases or evokes or stimulates ortriggers a reaction in the second organism! which responds to the senders (ehaviour!there(y turning it into a signal. ,his function of language to act upon a receiver wascalled (y Buhler the releasing or signalling function of language.

,o take an e&ample! a (ird may (e ready to fly away! and may e&press this (ye&hi(iting certain symptoms. ,hese may then release or trigger a certain response orreaction in a second (ird! and as a conse)uence it too may get ready to fly away.


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5or human language is very much richer. It has many functions! and dimensions! whichanimal languages do not have. ,wo of these new functions are most important for theevolution of reasoning and rationality7 the descriptive function! and the argumentativefunction.

As an e&ample of the descriptive function! I might now descri(e to you how two daysago a magnolia was flowering in my garden! and what happened when snow (egan to

fall. I might there(y e&press my feelings! and also release or trigger some feeling inyou7 you may perhaps react (y thinking of your magnolia trees. 'o the two lowerfunctions would (e present. But in addition to all this! I should have descri(ed to yousome facts; I should have made some descriptive statements; and these statements ofmine would (e factually true! or factually false.

4henever I speak I cannot help e&pressing myself; and if you listen to me you canhardly help reacting. 'o the lower functions are always present. ,he descriptivefunction need not (e present! for I may speak to you without descri(ing any fact. 5ore&ample! in showing or e&pressing uneasinesssay! dou(t a(out whether you willsurvive this long lectureI need not descri(e anything. 3et description! including thedescription of conectured states of affairs! which we formulate in the form of theoriesor hypotheses! is clearly an e&tremely important function of human language; and it is

that function which distinguishes human language most clearly from the various animallanguages 0although there seems to (e something approaching it in the language ofthe (ees1 . It is! of course! a function which is indispensa(le for science.

,he last and highest of the four functions to (e mentioned in this survey is theargumentative funnction of language! as it may (e seen at work! in its highest form ofdevelopment! in a welldisciplined critical discussion.

,he argumentative function of language is not only the highest of the four functions Iam here discussing! (ut it was also the latest of them to evolve. Its evolution has (eenclosely connected with that of an argumentative! critical! and rational attitude; andsince this attitude has led to the evolution of science! we may say that the

argumentative function of language has created what is perhaps the most powerfultool for (iological adaptation which has ever emerged in the course of organicevolution.

Like the other functions! the art of critical argument has developed (y the method oftrial and errorelimination! and it has had the most decisive influence on the humana(ility to think rationally. 05ormal logic itself may (e descri(ed as an organon of criticalargument. Like the descriptive use of language! the argumentative use has led to theevolution of ideal standards of control! or of regulative ideas 0using a *antian term1 7the main regulative idea of the descriptive use of language is truth 0as distinct fromfalsity1 ; and that of the argumentative use of language! in critical discussion! is validity0as distinct from invalidity1.

Arguments! as a rule! are for or against some proposition or descriptive statement; thisis why our fourth function the argumentative function must have emerged later thanthe descriptive function.2ven if I argue in a committee that the Fniversity ought not to authorie a certaine&penditure (ecause we cannot afford it! or (ecause some alternative way of using themoney would (e more (eneficial! I am arguing not only for or against a proposal (utalso for and!against some proposition for the proposition! say! that the proposed usewill not (e (eneficial! and against the proposition that the proposed use will (e(eneficial. 'o arguments! even arguments a(out proposals! as a rule (ear onpropositions! and very often on descriptive propositions.


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3et the argumentative use of language may (e clearly distinguished from itsdescriptive use! simply (ecause I can descri(e without arguing7 I can descri(e! that isto say! without giving reasons for or against the truth of my description.

6ur analysis of four functions of our language the e&pressive! the signalling! thedescriptive! and the argumentative functions may (e summed up (y saying that!

although it must (e admitted that the two lower functions the e&pressive andsignalling functionsare always present whenever the higher functions are present! wemust nevertheless distinguish the higher functions from the lower ones. 3et many(ehaviourists and many philosophers have overlooked the higher functions! apparently(ecause the lower ones are always present! whether or not the higher ones are.

J>

A9A8, from the new functions of language which have evolved and emerged togetherwith man! and with human rationality! we must consider another distinction of almoste)ual importance! the distinction (etween the evolution of organs and that of tools ormachines! a distinction to (e credited to one of the greatest of 2nglish philosophers!

'amuel Butler! the author of 2rewhon 0"@$1.

Animal evolution proceeds largely! though not e&clusively! (y the modification oforgans 0or (ehaviour1 or the emergence of new organs 0or (ehaviour1. Humanevolution proceeds! largely! (y developing new organs outside our (odies or persons7-e&osomatically! as (iologists call it! or -e&tra personally. ,hese new organs are tools!or weapons! or machines! or houses.

,he rudimentary (eginnings of this e&osomatic development can of course (e foundamong animals. ,he making of lairs! or dens! or nests! is an early achievement. I mayalso remind you that (eavers (uild very ingenious dams. But man! instead of growing(etter eyes and ears! grows spectacles! microscopes! telescopes! telephones! and

hearing aids. And instead of growing swifter and swifter legs! he grows swifter andswifter motor cars. 3et the kind of e&trapersonal or e&osomatic evolution whichinterests me here is this7 instead of growing (etter memories and (rains! we growpaper! pens! pencils! typewriters! dictaphones! the printing press! and li(raries.

,hese add to our languageand especially to its descriptive and argumentativefunctionswhat may (e descri(ed as new dimensions. ,he latest development 0usedmainly in support of our argumentative a(ilities1 is the growth of computers.

J>I

How are the higher functions and dimensions related to the lower ones: ,hey do not

replace the lower ones! as we have seen! (ut they esta(lish a kind of plastic controlover thema control with feed(ack.

,ake! for e&ample! a discussion at a scientific conference. It may (e e&citing andenoya(le! and give rise to e&pressions and symptoms of its (eing so; and thesee&pressions in their turn may release similar symptoms in other participants. 3et thereis no dou(t that up to a point these symptoms and releasing signals will (e due to! andcontrolled (y! the scientific content of the discussion; and since this will (e of adescriptive and of an argumentative nature! the lower functions will (e controlled (ythe higher ones. Moreover! though a good oke or a pleasant grin may let the lower


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functions win in the short run! what counts in the long run is a good argumenta validargument and what it esta(lishes or refutes. In other words! our discussion iscontrolled! though plastically! (y the regulative ideas of truth and of validity.

All this is strengthened (y the discovery and development of the new dimensions ofprinting and pu(lishing! especially when these are used for printing and pu(lishingscientific theories and hypotheses! and papers in which these are critically discussed.

I cannot do ustice to the importance of critical arguments here7 it is a topic on which Ihave written fairly e&tensively! and so I shall not raise it again here. I only wish tostress that critical arguments are a means of control7 they are a means of eliminatingerrors! a means of selection. 4e solve our pro(lems (y tentatively proposing variouscompeting theories and hypotheses! as trial (alloons! as it were; and (y su(mittingthem to critical discussion and to empirical tests! for the purpose of errorelimination.

'o the evolution of the higher functions of language which I have tried to descri(e may(e characteried as the evolution of new means for pro(lemsolving! (y new kinds oftrials! and (y new methods of errorelimination; that is to say! new methods forcontrolling the trials.

J>II

I CA< now give my solution to our first main pro(lem! that is! Comptons pro(lem of theinfluence ofineaning upon (ehaviour. It is this.

,he higher levels of language have evolved under the pressure of a need for the (ettercontrol of two things7 of our lower levels of language! and our adaptation to theenvironment! (y the method of growing not only new tools! (ut also! for e&ample! newscientific theories! and new standards of selection.


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I su(mit this as my solution of Comptons pro(lem; and (efore proceeding to solve/escartess pro(lem! I shall now (riefly outline the more general theory of evolutionwhich I have already used! implicitly! in my solution.

J>III

I 65528 my general theory with many apologies. It has taken me a long time to think itout fully! and to make it clear to myself.


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0+1 9ro(lemsolving always proceeds (y the method of trial and error7 new reactions!new forms! new organs! new modes of (ehaviour! new hypotheses! are tentatively putforward and controlled (y errorelimination.

0G1 2rrorelimination may proceed either (y the complete elimination of unsuccessfulforms 0the killingoff of unsuccessful forms (y natural selection1 or (y the 0tentative1

evolution of controls which modify or suppress unsuccessful organs! or forms of(ehaviour! or hypotheses.

0%1 ,he single organism telescopes into one (ody! as it were! the controls developedduring the evolution of its phylumust as it partly recapitulates! in its ontogeneticdevelopment! its phylogenetic evolution.

0D1 ,he single organism is a kind of spearhead of the evolutionary se)uence oforganisms to which it (elongs 0its phylum1 7 it is itself a tentative solution! pro(ing intonew environmental niches! choosing an environment and modifying it. It is thus relatedto its phylum almost e&actly as the actions 0(ehaviour1 of the individual organism arerelated to this organism7 the individual organism! and its (ehaviour! are (oth trials!which may (e eliminated (y errorelimination.

01 Fsing 9 for pro(lem! ,' for tentative solutions! 22 for errorelimination! we candescri(e the fundamental evolutionary se)uence of events as follows7

9 ,' 22 9.

But this se)uence is not a cycle7 the second pro(lem is! in general! different from thefirst7 it is the result of the new situation which has arisen! in part! (ecause of thetentative solutions which have (een tried out! and the errorelimination which controlsthem. In order to indicate this! the a(ove schema should (e rewritten7

9. ,' 22


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0""1 ,he theory here proposed distinguishes (etween 9i and 9$i and it shows that thepro(lems 0or the pro(lem situations1 which the organism is trying to deal with are oftennew! and arise themselves as products of the evolution. ,he theory there(y givesimplicitly a rational account of what has usually (een called (y the somewhat du(iousnames of -creative evolution or -emergent evolution.%G

0"$1 6ur schema allows for the development of erroreliminating controls 0warningorgans like the eye; feed(ack mechanisms1 ; that is! controls which can eliminateerrors without killing the organism; and it makes it possi(le! ultimately! for ourhypotheses to die in our stead.

JIJ

2ACH organism can (e regarded as a ! hierarchical system of plastic controlsas asystem of clouds controlled (y clouds. ,he controlled su(systems make trialanderrormovements which are partly suppressed and partly restrained (y the controllingsystem.

4e have already met an e&ample of this in the relation (etween the lower and higherfunctions of language. ,he lower ones continue to e&ist and to play their part; (ut theyare constrained and controlled (y the higher ones.

Another characteristic e&ample is this. If I am standing )uietly! without making anymovement! then 0according to the physiologists1 my muscles are constantly at work!contracting and rela&ing in an almost random fashion 0see ,'I to ,'!! in thesis 0@1 ofthe preceding section1! (ut controlled! without my (eing aware of it! (y errorelimination 0221 so that every little deviation from my posture is almost at oncecorrected. 'o I am kept standing! )uietly! (y more or less the same method (y whichan automatic pilot keeps an aircraft steadily on its course.

,his e&ample also illustrates the thesis 0i1 of the preceding sectionthat each organismis all the time engaged in pro(lemsolving (y trial and error; that it reacts to new andold pro(lems (y more or less chancelike!%% or cloudlike! trials which are eliminated ifunsuccessful. 0If successful! they increase the pro(a(ility of the survival of mutationswhich -simulate the solutions so reached! and tend to make the solution hereditary!%D(y incorporating it into the spatial structure or form of the new organism.1

,he method of trial and errorelimination does not operate with completely chancelikeor random trials 0as has (een sometimes suggested1! even though the trials may lookpretty random; there must (e at least an -aftereffect 0in the sense of my ,he Logic of'cientific /iscovery! pp. "D$ ff.1. 5or the organism is constantly learning from itsmistakes! that is! it esta(lishes controls which suppress or eliminate! or at least reducethe fre)uency of! certain possi(le trials 0which were perhaps actual ones in its

evolutionary past1.

JJ

,HI' is a very (rief outline of the theory. It needs! of course! much ela(oration. But Iwish to e&plain one point a little more fullythe use I have made 0in theses 0I1 to 0+1 ofsection &vin1 of the terms -pro(lem and -pro(lemsolving and! more particularly! myassertion that we can speak of pro(lems in an o(ective! or nonpsychological sense.


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,he point is important! for evolution is clearly not a conscious process. Many (iologistssay that the evolution of certain organs solves certain pro(lems; for e&ample! that theevolution of the eye solves the pro(lem of giving a moving animal a timely warning tochange its direction (efore (umping into something hard.


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It is different with primitive man! and with the amoe(a. Here there is no criticalattitude! and so it happens more often than not that natural selection eliminates amistaken hypothesis or e&pectation (y eliminating those organisms which hold it! or(elieve in it. 'o we can say that the critical or rational method consists in letting ourhypotheses die in our stead7 it is a case of e&osomatic evolution.

JJII

H282 I may perhaps turn to a )uestion which has given me much trou(le although inthe end I arrived at a very simple solution.

,he )uestion is7 Can we show that plastic controls e&ist: Are there inorganic physicalsystems in nature which may (e taken as e&amples or as physical models of plasticcontrols:

It seems that this )uestion was implicitly answered in the negative (y many physicistswho! like /escartes or Compton! operate with masterswitch models! and (y manyphilosophers who! like Hume or 'chlick! deny that anything intermediate (etween

complete determinism and pure chance can e&ist. Admittedly! cy(erneticists andcomputer engineers have more recently succeeded in constructing computers made ofhardware (ut incorporating highly plastic controls; for e&ample! computers with (uiltinmechanism for chancelike trials! checked or evaluated (y feed(ack 0in the manner ofan automatic pilot or a selfhoming device1 and eliminated if erroneous. But thesesystems! although incorporating what I have called plastic controls! consist essentiallyof comple& relays of masterswitches. 4hat I was seeking! however! was a simplephysical model of 9eircean indeterminism; a purely physical system resem(ling a verycloudy cloud in heat motion! controlled (y some other cloudy cloudsthough (ysomewhat less cloudy ones.

If we return to our old arrangement of clouds and clocks! with a cloud on the left and a

clock on the right! then we could say that what we are looking for is somethingintermediate! like an organism or like our cloud of gnats! (ut not alive7 a pure physicalsystem! controlled plastically and softly! as it were.

Let us assume that the cloud to (e controlled is a gas. ,hen we can put on the e&tremeleft an uncontrolled gas which will soon diffuse and so cease to constitute a physicalsystem. 4e put on the e&treme right an iron cylinder filled with gas7 this is our e&ampleof a -hard control! a -castiron control. In (etween! (ut far to the left! are many moreor less softly controlled systems! such as our cluster of gnats! and huge (alls ofparticles! such as a gas kept together (y gravity! somewhat like the sun. 04e do notmind if the control is far from perfect! and many particles escape.1 ,he planets mayperhaps (e said to (e castiron controlled in their movementscomparatively speaking!of course! for even the planetary system is a cloud! and so are all the milky ways! star

clusters! and clusters of clusters. But are there! apart from organic systems and thosehuge systems of particles! e&amples of any softly controlled small physical systems:

I think there are! and I propose to put in the middle of our diagram a childs (alloon or!perhaps (etter! a soap (u((le; and this! indeed! turns out to (e a very primitive and inmany respects an e&cellent e&ample or model of a 9eircean system and of a soft kindof plastic control.

,he soap (u((le consists of two su(systems which are (oth clouds and which controleach other7 without the air! the soapy film would collapse! and we should have only a


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drop of soapy water. 4ithout the soapy film! the air would (e uncontrolled7 it woulddiffuse! ceasing to e&ist as a system. ,hus the control is mutual; it is plastic! and of afeed(ack character. 3et it is possi(le to make a distinction (etween the controlledsystem 0the air1 and the controlling systems 0the film1 7 the enclosed air is not onlymore cloudy than the enclosing film! (ut it also ceases to (e a physical 0selfinteracting1 system if the film is removed. As against this! the film! after removal of theair! will form a droplet which! though of a different shape! may still (e said to (e a

physical system.

Comparing the (u((le with a -hardware system like a precision clock or a computer!we should of course say 0in accordance with 9eirces point of view1 that even thesehardware systems are clouds controlled (y clouds. But these -hard systems are (uiltwith the purpose of minimiing! so far as it is possi(le! the cloudlike effects ofmolecular heat motions and fluctuations7 though they are clouds! the controllingmechanisms are designed to suppress! or compensate for! all cloudlike effects as faras possi(le. ,his holds even for computers with mechanisms simulating chanceliketrialanderror mechanisms.

6ur soap (u((le is different in this respect and! it seems! more similar to an organism7the molecular effects are not eliminated (ut contri(ute essentially to the working of the

system which is enclosed (y a skina permea(le wallD" that leaves the system -open!and a(le to -react to environmental influences in a manner which is (uilt! as it were!into its -organiation7 the soap (u((le! when struck (y a heat ray! a(sor(s the heat0much like a hothouse1! and so the enclosed air will e&pand! keeping the (u((lefloating.

As in all uses of similarity or analogy we should! however! look out for limitations; andhere we might point out that! at least in some organisms! molecular fluctuations areapparently amplified and so used to release trialanderror movements. At any rate!amplifiers seem to play important roles in all organisms 0which in this respect resem(lesome computers with their masterswitches and cascades of amplifiers and relays1. 3etthere are no amplifiers in the soap (u((le.

However this may (e! our (u((le shows that natural physical cloudlike systems whichare plastically and softly controlled (y other cloudlike systems do e&ist. 0Incidentally!the film of the (u((le need not! of course! (e derived from organic matter! though itwill have to contain large molecules.1

JJIII

,H2 evolutionary theory here proposed yields an immediate solution to our secondmain pro(lemthe classical Cartesian (odymind pro(lem. It does so 0without sayingwhat -mind or -consciousness is1 (y saying something a(out the evolution! andthere(y a(out the functions! of mind or consciousness.

4e must assume that consciousness grows from small (eginnings; perhaps its firstform is a vague feeling of irritation! e&perienced when the organism has a pro(lem tosolve such as getting away from an irritant su(stance. However this may (e!consciousness will assume evolutionary significanceand increasing significancewhenit (egins to anticipate possi(le ways of reacting7 possi(le trial anderror movements!and their possi(le outcomes.

4e can say now that conscious states! or se)uences of conscious states! may functionas systems of control! of errorelimination7 the elimination! as a rule! of 0incipient1


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(ehaviour! that is 0incipient1 movement. Consciousness! from this point of view!appears as ust one of many interacting kinds of control; and if we remem(er thecontrol systems incorporated for e&ample in (ookstheories! systems of law! and allthat constitutes the universe of meaningsthen consciousness can hardly (e said to (ethe highest control system in the hierarchy. 5or it is to a considera(le e&tent controlled(y these e&osomatic linguistic systemseven though they may (e said to (e produced(y consciousness. Consciousness in turn is! we may conecture! produced (y physical

states; yet it controls them to a considera(le e&tent. ust as a legal or social system isproduced (y us! yet controls us! and is in no reasona(le sense -identical to or -parallelwith us! (ut interacts with us! so states of consciousness 0the -mind1 control the (ody!and interact with it.

,hus there is a whole set of analogous relationships. As our e&osomatic world ofmeanings is related to consciousness! so consciousness is related to the (ehaviour ofthe acting individual organism. And the (ehaviour of the individual organism issimilarly related to its (ody! to the individual organism taken as a physiological system.

,he latter is similarly related to the evolutionary se)uence of organismsthe phylum ofwhich it forms the latest spearhead! as it were7 as the individual organism is thrown upe&perimentally as a pro(e (y the phylum and yet largely controls the fate of thephylum! so the (ehaviour of the organism is thrown up e&perimentally as a pro(e (y

the physiological system and yet controls! largely! the fate of this system. 6urconscious states are similarly related to our (ehaviour. ,hey anticipate our (ehaviour!working out! (y trial and error! its likely conse)uences; thus they not only control (utthey try out! deli(erate.

4e now see that this theory offers us an almost trivial answer to /escartess pro(lem.4ithout saying what -the mind is! it leads immediately to the conclusion that ourmental states control 0some of1 our physical movements! and that there is some giveandtake! some feed(ack! and so some interaction! (etween mental activity and theother functions of the organism.

,he control will again (e of the -plastic kind; in fact all of us especially those who play

a musical instrument such as the piano or the violinknow that the (ody does notalways do what we want it to do; and that we have to learn! from our illsuccess! howto modify our aims! making allowances for those limitations which (eset our control7though we are free! to some considera(le e&tent! there are always conditionsphysicalor otherwisewhich set limits to what we can do. 06f course! (efore giving in! we arefree to try to transcend these limits.1

,hus! like /escartes! I propose the adoption of a dualistic outlook! though I do not ofcourse recommend talking of two kinds of interacting su(stances. But I think it ishelpful and legitimate to distinguish two kinds of interacting states 0or events1! physiochemical and mental ones. Moreover! I suggest that if we distinguish only these twokinds of states we still take too narrow a view of our world7 at the very least we shouldalso distinguish those artifacts which are products of organisms! and especially the

products of our minds! and which can interact with our minds and thus with the state ofour physical environment. Although these artifacts are often mere (its of matter!-mere tools perhaps! they are even on the animal level sometimes consummate worksof art; and on the human level! the products of our minds are often very much morethan (its of mattermarked (its of paper! say; for these (its of paper may representstates of a discussion! states of the growth of knowledge! which may transcend0sometimes with serious conse)uences1 the grasp of most or even all of the minds thathelped to produce them. ,hus we have to (e not merely dualists! (ut pluralists; and wehave to recognie that the great changes which we have (rought a(out! oftenunconsciously! in our physical universe show that a(stract rules and a(stract ideas!


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some of which are perhaps only partially grasped (y human minds! may movemountains.

JJI>

As an afterthought! I should like to add one last point.

It would (e a mistake to think that! (ecause of natural selection! evolution can onlylead to what may (e called -utilitarian results7 to adaptations which are useful inhelping us to survive.

ust as! in a system with plastic controls! the controlling and controlled su(systemsinteract! so our tentative solutions interact with our pro(lems and also with our aims.

,his means that our aims can change and that the choice of an aim may (ecome apro(lem; different aims may compete! and new aims may (e invented and controlled(y the method of trial and errorelimination.

Admittedly! if a new aim clashes with the aim of surviving! then this new aim may (eeliminated (y natural selection. It is well known that many mutations are lethal and

thus suicidal; and there are many e&amples of suicidal aims. 6thers are perhapsneutral with respect to survival.

Many aims that at first are su(sidiary to survival may later (ecome autonomous! andeven opposed to survival; for e&ample! the am(ition to e&cel in courage! to clim(Mount 2verest! to discover a new continent! or to (e the first on the Moon; or theam(ition to discover some new truth.

6ther aims may from the very (eginning (e autonomous departures! independent ofthe aim to survive. Artistic aims are perhaps of this kind! or some religious aims! and tothose who cherish them they may (ecome much more important than survival.

All this is part of the supera(undance of lifethe almost e&cessive a(undance of trialsand errors upon which the method of trial and errorelimination depends.

It is perhaps not uninteresting to see that artists! like scientists! use this trialanderrormethod. a painter may put down! tentatively! a speck of colour and step (ack for acritical assessment of its efect in order to alter it if it does not solve the pro(lem hewants to solve. And it may happen that an une&pected or accidental effect of histentative trial a colour speck or (rush strokemay change his pro(lem! or create anew su(pro(lem! or a new aim7 the evolution of artistic aims and of artistic standards0which! like the rules of logic! may (ecome e&osomatic systems of control1 proceedsalso (y the trialanderror method.

4e may perhaps here look (ack for a moment to the pro(lem of physical determinism!

and to our e&ample of the deaf physicist who had never e&perienced music (ut would(e a(le to compose a Moart opera or a Beethoven symphony! simply (y studyingMoarts or Beethovens (odies and their environments as physical systems! andpredicting where their pens would put down (lack marks on lined paper. I presentedthese as unaccepta(le conse)uences of physical determinism. Moart and Beethovenare! partly! controlled (y their -taste! their system of musical evaluation. 3et thissystem is not cast iron (ut rather plastic. It responds to new ideas! and it can (emodified (y new trials and errorsperhaps even (y an accidental mistake! anunintended discord.


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In conclusion! let me sum up the situation.4e have seen that it is unsatisfactory to look upon the world as a closed physicalsystemwhether a strictly deterministic system or a system in which whatever is notstrictly determined is simply due to chance7 on such a view of the world humancreativeness and human freedom can only (e illusions. ,he attempt to make use of)uantumtheoretical indeterminacy is also unsatisfactory! (ecause it leads to chancerather than freedom! and to snapdecisions rather than deli(erate decisions.

I have therefore offered here a different view of the worldone in which the physicalworld is an open system. ,his is compati(le with the view of the evolution of life as aprocess of trial and errorelimination; and it allows us to understand rationally! thoughfar from fully! the emergence of (iological novelty and the growth of human knowledgeand human freedom.

I have tried to outline an evolutionary theory which takes account of all this and whichoffers solutions to Comptons and /escartess pro(lems. It is! I am afraid! a theorywhich manages to (e too humdrum and too speculative at the same time; and eventhough I think that testa(le conse)uences can (e derived from it! I am far fromsuggesting that my proposed solution is what philosophers have (een looking for. But Ifeel that Compton might have said that it presents! in spite of its faults! a possi(le

answer to his pro(lemand one which might lead to further advance.

k. r. popper: of clouds and clocks

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