Reading Guide


Objective Knowledge
An Evolutionary Approach


by Karl Popper

Why Objective Knowledge Matters

This book signalled a significant development in Popper’s thought to advance the twin themes of evolution and objective knowledge. This added  a great deal of depth to the “objective turn” in his work.

He introduced the four-stage problem solving schema which helps to illustrate the synergy of imagination and reason required in the different phases of problem solving activity.

He gave a more detailed account of the levels of language (following Buhler), thus providing a more useful approach to the topic than that offered by most of philosophers who took “the linguistic turn” and became obsessed with language.

He spelled out some additional aspects of the approach that he called “situational analysis” for explanation of human action and events in the social sciences, history and the humanities.

This perspective has two striking features.

First, it helps to explain how the problem solving approach heals the artificial rift between science and the humanities that became a fashionable concern in the “two cultures” debate of the 1960s.

Second, it points the way towards a general theory  of human motivation which avoids the reduction of human behaviour on the one hand to purely psychological or biological drives and  on the other hand to purely environmental or social factors.

The key ideas in this book need to be read in the context of the “four turns” that Popper introduced into philosophy: the conjectural or “hermeneutic” turn; the focus on objective or interpersonal knowledge rather than subjective beliefs; attention to the social aspect of science and the need for “rules of the road”; and the return of metaphysics.

Objective Knowledge in Popper’s Publication Program

What else was happening at the time?

It was a decade after Conjectures and Refutations, also a decade after the appearance of Kuhn, the problem with Lakatos was just starting to emerge.

It came two years before the Schillp volumes which were in preparation since about 1965.

As to the critical reception, it appeared when Popper’s stocks were falling due to the influence of  Kuhn, Lakatos and Feyerabend. Bartley was no longer on the team and  Popper was no longer based in the LSE.


The first chapter spells out the theory of  conjectural knowledge as a solution to the problem of induction. The second make an argument for commonsense realism against the commonsense (subjective) theory of knowledge. There is a chapter on the aim of science (truth) which is a pre-release from the long awaited Postscript to The Logic of Scientific Discovery. There is a chapter on Tarski’s Theory of Truth.

These were all familiar Popperian themes and added some depth but not much that was new. The really interesting part of the book is the emergence of  evolution and “objective knowledge” in five chapters based on papers delivered on various occasions during the 1960s.

Bill Bartley described how Popper sprang these ideas on his seminar participants, almost out of the blue, on Tuesday November 15, 1960.

“On that day the members of Popper’s seminar had assembled as usual around the long table in the old seminar room on the fourth floor of the old building of the London School of Economics. When Popper appeared he announced that he would abandon the usual format and would read a new paper of his own. That new paper, which spoke of ‘three worlds’, of biology, and gave qualified support to Hegel’s theory of objective mind, took the members of the seminar off guard.”

Evolution and the Tree of Knowledge

That was the title of Popper’s Herbert Spencer Lecture, delivered at Oxford in October 1961. The paper began with some remarks on problems and the growth of knowledge and moved on to methods in biology and especially the theory of evolution.

He stated some general theses:

First, there is no royal road to success in science. “If anyone should think of scientific method as a way that leads to success in science, he will be disappointed.”

Second, there is no way to justify scientific results. “A scientific result can only be criticized, and tested…(and all) that can be said in its favour is that it seems to be better, more interesting, more powerful, more promising, and a better approximation to truth, than its competitors.”

And “There is no point in discussing or criticizing a theory unless we try all the time to put it in its strongest form, and to argue against it only in that form.”

Rationality and Freedom

The next paper in the series applied the new approach on the old issues of rationality and freedom in the Arthur  Holly  Compton  Memorial lecture delivered at Washington University in 1965, "Of Clouds and Clocks:  An Approach to the Problem of Rationality and  the  Freedom  of Man". 

One of the issues that Popper sought to illuminate in this paper is the role of plans and intentions in human action, especially the “plastic” nature of that control due to our capacity modify or cancel plans and intentions. The idea of plastic control provides a promising approach to the problems of freedom and determinism.

In this lecture Popper set out to produce an alternative to two opposing theories of human freedom.  The first of these  is  the determinist   nightmare  according  to  which  the  whole  world, including ourselves,  is a machine which runs as if by clockwork. In  the  words  of the German poet  Novalis  this  view  converts '...the  infinite  creative music of the universe into  the  dull clappering of a gigantic mill,  driven by the steam of chance and floating upon it,  a mill,  without architect and without miller, grinding  itself  to pieces'.

That view destroys the idea of  human creativity.  "It reduces to a complete illusion the idea that in preparing  this lecture I have used my brain to create  something new".

An  alternative derives from Heisenberg's Uncertainty Principle. Some events at the sub-atomic level happen at random,  these random events may become amplified to produce unexpected happenings at higher levels, and so we have the chance to do something original.

Popper was not  satisfied  with these  alternatives  because  he suggests  that the real problem is to explain   how  non-physical things such as aims,  plans, values and purposes manage  to exert effects  in  the  physical world.  He confronted what  he  called "Compton's  Problem" which Compton discovered after he agreed  to deliver a lecture at Yale University at 5 p.m.  on November 10th. This  decision  introduced  a kind of plastic  control  into  his movements   on   and  around  November  10th.   It  was   not   a completely  rigid  control  because the lecture  might  not  have started at the right time and it could even have been  cancelled. There  was an element of freedom in the situation but it did  not  derive from chance.  What was the nature of this plastic control? How is it that speakers usually turn up on the right day, at more or less the correct time? Popper set out to solve this problem of freedom  within  plastic  control   by way of  a  new  theory  of language in the context of a revised theory of evolution.

The  revised  theory of evolution  is summed up in twelve theses,  though not all of these need to be spelled out here.

1.  All  organisms  are constantly,  day and  night,  engaged  in problem solving.

2.   These problems are problems in an objective sense.  They can be    hypothetically   reconstructed  by   hindsight.   Objective problems in this sense need not have their conscious  counterpart and where they do,  the conscious problem need not be the same as the objective problem. A plant seed has to solve many problems to survive but it is not conscious of any of them.

3.  Problem  solving  always proceeds by the method of trial  and error.

4.  Error elimination may proceed by the complete elimination  of unsuccessful  forms  or  by the tentative evolution  of  controls which  modify  or  suppress  unsuccessful  organs  or  forms   of behaviour or hypotheses.

7.  Using 'P' for problem,  'TS' for tentative solution, 'EE' for error  elimination,  we can describe the fundamental evolutionary sequence as follows:

P(1)  --->   TS  --->    EE  --->    P(2, 3, 4 etc)

Confronted  with  a  problem,   the  organism   offers  tentative solutions;  these are subjected to a process of error elimination (natural  selection,  critical  discussion etc) and new  problems emerge in the process.

10.  Not  all  problems  in this  system  are  survival  problems although  the  earliest  problems may have  been  sheer  survival problems.

12.  This scheme allows for the development of  error-eliminating controls  (warning  organs like the eye;  feed-back  mechanisms); that is,  controls which can eliminate errors without killing the organism;   and  it  makes  it  possible,   ultimately,  for  our hypotheses to die in our stead.

So  much  for  the outline of the  revised  evolutionary  theory. Popper  suggested that plastic control over human  activities  is maintained with the assistance of language which has emerged,  as has consciousness, somewhere along the evolutionary pathway.

Popper's  theory  of  language

Popper  distinguished four levels of language.  Starting from the lowest these are :

I.  The  symptomatic  or  expressive function,  which  can  exist without even a second party.

II.  The  releasing or signalling  function,  when  communication occurs from a sender to a receiver.

III. The  descriptive function which involves naming things.

IV.  The  critical  or argumentative function which occurs  in  a well-disciplined discussion.
The  two lower forms occur in animals (and in machines) and  they can  occur  without the higher functions being present.  The  two higher forms appear to be restricted to humans;  but they do  not occur  in  all  human  use  of  language  (which  can  be  merely symptomatic  or  signalling),  and they cannot occur without  the lower functions being present.  Thus one may attempt to  'reduce' all  use  of  language to the lower functions  because  they  are always present while the higher functions may be missing.

Popper  suggests that human consciousness,  the consciousness  of self,  is a result of language. In addition,  the descriptive use of  language  gives  us access to ideas  and  abstractions  which introduce  a  degree  of control into our behaviour  beyond  that exerted by instincts and reflexes.

The evolution of ideas and the three worlds

In "A Realist View of  Logic,  Physics  and History" he enlarged some  points  made briefly  in "Of Clouds and Clocks";  the evolution of plants  and animals proceeds for the most part by the modification of  organs or  behaviour,  while in contrast human evolution proceeds mainly by  the  development of organs  outside  our  bodies.  These new external organs may be tools, weapons, machines or ideas.

'Man, some  modern philosophers tell us,  is alienated from  his world:  he  is  a stranger and afraid in a world he  never  made. Maybe  he is:  yet so are animals and even plants.  They too were born, long ago, into a physico-chemical world they never made.  But  although they did not make their world,  these living things changed it beyond all recognition,  and, indeed, remade the small corner of the universe into which they were born...Last came man, who  for  a  long  time did not change  his  environment  in  any remarkable  way...Yet  we have created a new kind of  product  or artefact which promises in time to work changes in our corner  of the  world  as  great as those worked by  our  predecessors,  the oxygen-producing plants, or the island building corals. These new products, which are decidedly of our own making,  are our myths, our ideas, and especially our scientific theories'.

Popper described the four-stage problem-solving scheme and then went on to deal some aspects of the growth of knowledge under four headings.

1.Realism and Pluralism: Reduction vs Emergence.
2.Pluralism and Emergence in History.
3.Realism and Subjectivism in Physics.
4.Realism in Logic.

On the reductionism vs emergence, the question is whether the sciences can be reduced to physics; it seems that a great deal of chemistry has been reduced in that way but biology remains a challenge, and even more so the world of human consciousness. Popper wrote that as a rationalist he wished and hoped for successful reduction but he also thought that quite likely life would remain as an emergent property of physical bodies.

Moving on to pluralism and emergence in history, he started with the history of life on earth and then moved on to the story of mankind which he very largely regarded as the history of our knowledge, our ideas and especially our theories about the world.

“The student of the history of ideas will find that ideas have a kind of life (this is a metaphor of course) ; that they can be misunderstood, rejected, and forgotten; they can reassert themselves, and come to life again. Without metaphor, however, we can say they are not identical with any one man’s thought or belief; that they can exist even if universally misunderstood and rejected.”

On the topic of realism and subjectivism in physics he examined Boltzmann’s theory of the subjectivity of the direction of time and Heisenberg’s interpretation of indeterminacy and the lower limit to the effect of the observer’s interference with the observed object.
He noted that the Heisenberg formula for energy is usually derived in a complicated manner but that is not necessary, it does not have to be derived from the new quantum theory but can be derived from Planck’s old quantum postulate. On that basis the Heisenberg formulae can be interpreted as statistical scatter relations and are in principle testable.
“Heisenberg himself noted that such measurements are possible, but he said that it was ‘a matter of personal belief’ or ‘personal taste’ whether or not we attach meaning to them; and ever since this remark they have been universally disregarded as meaningless. But they are not meaningless, for they have a definite function: they are tests of the very formulae in question; that is, of the indeterminacy formulae qua scatter relations.”

Defending realism in logic, he insisted that he did not look on logic as a kind of game.
“I know all about so-called alternative systems of logic and I have actually invented one myself, but alternative systems of logic can be discussed from very different points of view. One might think that it is a matter of choice or convention which logic one adopts. I disagree with this view.

For Popper, logic is essentially a tool of criticism, robust criticism. It is concerned with the derivation or deduction of truth and falsity through chains of argument.

“In a valid inference truth is transmitted from the premises to the conclusion. This can be used on so-called ‘proofs’. But falsity is also retransmitted from the conclusion to (at least) one of the premises, and this is used in disproofs or refutations, and especially in critical discussions.”

The disproof of the premises is the familiar logic of Modus Tollens, the logic of falsification.
He then gave some extended criticism of the intuitionist logic of Brouwer, drawing upon some ideas from Tarski. 

Epistemology Without a Knowing Subject

In "Epistemology Without  a Knowing  Subject",   delivered  in 1967;  he  considered  the status of ideas and their implications for us.  He rehearsed the "three worlds" theory to argue that human language, so far as it contains information, belongs to a "third world" of objective contents of thought.

“For a humanist our approach may be important because it suggests a  new  way of looking at the relations between  ourselves  - the subjects  - and  the objects of our  endeavours.  The  incredible thing  about  life,  evolution  and mental growth  is  just  this method of give and take, this interaction between our actions and their  results  by which we constantly transform  ourselves,  our talents,  our  gifts...This  is how we lift ourselves up  by  our bootstraps  out of the morass of our ignorance;  how we  throw  a rope into the air and then swarm up it - if it gets any purchase, however  precarious...What makes our efforts differ from those of the amoeba is only that our rope may get a hold in a third  world of  critical  discussion:  a  world  of  language,  of  objective knowledge.  This makes it possible for us to  discard some of our competing  theories.  So  if  we  are lucky,  we  may  succeed  in surviving  some  of our mistaken theories while the  amoeba  will perish.”

This chapter runs to 46 pages and covers a very large range of issues under seven headings.
1.Three Theses on Epistemology and the Third World
2.A Biological Approach to the Third World
3.The Objectivity and Autonomy of the Third World
4.Language, Criticism and the Third World
5.Historical Remarks
6.Appreciation and Criticism of Brouwer’s Epistemology
7.Subjectivism in Logic, Probability Theory and Physical Science

Three Theses

1.“Traditional epistemology has studied knowledge or thought in a subjective sense – in the sense of the ordinary usage of the words ‘I know’ or ‘I am thinking’. This has led students of epistemology into irrelevances: while intending to study scientific knowledge, they studied in fact something which is of no relevance to scientific knowledge…Thus my first thesis is that the traditional epistemology, of Locke, Berkely, Hume, and even of Russell, is irrelevant, in a pretty strict sense of the term.”

2.“My second thesis is that what is relevant for epistemology is the study of scientific problems and problem situations, of scientific conjectures (scientific hypotheses or theories), of scientific discussions, of critical arguments and their evaluation in scientific arguments; and therefore of scientific journals and books, and of experiments and their evaluation in scientific arguments; or, in brief, that the study of a largely autonomous third world of objective knowledge is of decisive importance for epistemology.”

3.“I have a third thesis. An objectivist epistemology which studies the third world can help to throw an immense amount of light upon the second world of subjective consciousness, especially upon the subjective thought processes of scientists; but  the converse is not true.”
The starting point is the “three worlds” theory, so without taking the words world or universe too seriously it is possible to distinguish (1) a world of physical objects and states, of sticks, stones and electrons etc (2) a world of mental states and consciousness, and (3) “a world of objective contents of thought, especially of scientific and poetic thoughts and of works of art.”
One of the functions of the three world theory is to challenge “belief philosophers” (which are concerned with the justification of beliefs) to abandon the quest for belief and focus instead on critical preference.

He offered three supporting theses.

1.The third world is a natural product “of the human animal, comparable to a spider’s web.

2.The third world is “largely autonomous”, even though it is manmade and exerts feedback upon us.

3.Objective knowledge grows through interaction between ourselves and the third world, with a close analogy to biological growth and the evolution of plants and animals.

The Biological Approach

In this section of the paper he elaborated on the way human products, especially knowledge, can be approached in the objective manner by analogy with the study of biological products including behaviour.

The Objectivity and Autonomy of the Third World

One of the justifications for the subjective approach to objective knowledge is the idea that a book is nothing without a reader. One of Popper’s counter-examples is the phenomenon of  the book that is not read by anyone or has been computer-generated. It still has contents that are available regardless of the use that is made of them.

One of the most exciting aspects of the three world theory is the emphasis on the unintended relationships and consequences that turn up when you start to pursue problems in a serious and persistent manner. This means “unpacking” the consequences and implications of the theories which are the objects of investigation.

“A large part of the objective third world of actual and potential theories and books and arguments arises as an unintended by-product of the actually produced books and arguments.”

All of the interesting problems in number theory provide examples. The sequence of natural numbers is a human construction but then  combinations and possibilities and problems emerge and these become more complex and more unexpected as we investigate the properties of the new world of numbers and mathematics.

Language and Criticism

Here Popper spelled out Buhler’s theory of the levels of language and the fourth level proposed by Popper himself. The two lower function of language are (1) self-expression and (2) signalling. These are shared by animals and humans (and even machines). Then (3) description is a function of the human use of language (with the dance of bees as an interesting transition case) and (4) is the argumentative function which Popper added.
With the evolution of the descriptive function, there emerges the regulative idea of truth, that is, a description that fits the facts. And with the emergence of the argumentative function of language, criticism can be used as a major instrument in the growth of knowledge.

Historical Remarks

In this section Popper examined the role of “third realms” of various kinds in Plato and Neo-Platonism, Hegel, Bolzano and Frege. On Plato, he repeated some of the criticisms from past works like The Open Society, pointing out how Plato set philosophy on the path of looking for the ultimate explanation of things in terms of essences, hypostasized words, hence the error of “essentialism”.

On Popper’s interpretation Hegel was a kind of Platonist but the ideas were not fixed and eternal as they were for Plato, instead they are for ever changing; also they are not autonomous, they are conscious phenomena and so are more directly comparable to Popper’s world 2 of consciousness, except to course that Hegel’s ideas are not individualistic. There is no provision for give and take between the individual creative element and the world of ideas that is so important for Popper.

Bolzano and Frege apparently anticipated Popper’s objectivism but did not unpack the consequences in a wide range of applications.

Brouwer’s Epistemology

Popper wrote several pages in tribute to Brouwer who he may have expected to attend the conference were Popper read this paper (he died shortly before the event). Popper advised people who are not up to speed on Brouwer’s intuitionist philosophy of mathematics to pass by this section which goes into some depth on Brower’s epistemology, though Brouwer is rarely discussed in connection with the theory of knowledge.

Subjectivism in Logic, Probability and Physics

Here Popper touched on this (then) 35 year against the subjective interpretation of the probability calculus, which Popper regarded as a capital error in quantum physics.
Discovery, Humanism and Self-Transcendence

The last section is particularly interesting, it seems that momentarily Popper’s objectivism was put aside and there was a glimpse of the human being, “existential Popper” who was capable of making a reference to “the reality of human suffering” in the midst of a tract on quantum physics. He spoke, as usual, about learning by imaginative criticism but he went further than usual.

“This is how we transcend our local and temporal environment by trying to think of circumstances beyond our experience…This is how we lift ourselves by our bootstraps out of this morass of our ignorance; how we may throw a rope into the air and then swarm up it – if it gets any purchase, however precarious, on any little twig. What makes our efforts different from those of an animal or of an amoeba is only that our rope may get a hold in a third world of critical discussion: a world of language, of objective knowledge.”

He could have gone further to mention values, aims, objectives and life plans. Charlotte  Buhler, the wife and colleague of his great teacher Karl Buhler, had a research interest in the diaries and plans of school children. She later became a prime mover in the Third Force of Humanistic Psychology in the US. Popper never mentioned her and so it remains a mystery whether he picked up some hint of the power of life planning. In any case, a nonconforming and priggish young man became a great reformer in the philosophy of science and then turned to effect the same revolution in the human sciences. Whatever motivated him to set his feet on that course we should be grateful.

On the Theory of the Objective Mind

The final  paper was delivered at the  fourteenth  International Philosophical Congress at Vienna in 1968. Gunter Zehm reported on this congress in Encounter (Feb. 1969).

'Sir Karl Popper rode his hobby-horse  and described the mode  of "understanding" historical processes as the logical analysis of a historical problem:  i.e.  as a process having nothing to do with the  capacity for empathy.  He did this in the course of a  paper "On the Theory of the Objective Mind" which can be  appropriately described  as the real (and only) sensation of the  congress...In contrast  to  all  the  Utopians and Ideologists  at  the  Vienna Congress,  he  said  nothing for which he could  not  immediately produce  demonstrable proofs.  Nevertheless there was more  human hope  in  his  paper than in all the  sunny  propaganda  speeches combined'.

In this paper he suggested that psychology may have to be revolutionised by looking at the human mind as an  organ  for interacting with the objects of the third world.  It is important to  note  that  this  "third world" theory  does  not  carry  any theistic consequences.

A unifying theme

The  theory  of  problem-solving by trial and  error  provides  a unifying  theme  that  runs  through the  activities  of  plants, animals,  artists and scientists.  This common perspective may be useful as we move into the 'ecological age' and as a byproduct it breaks  the artificial barriers erected between the sciences  and the humanities.

This  perspective also shows the way towards a general theory  of human motivation which avoids the reduction of human behaviour on the one hand to purely psychological or biological drives and  on the other hand to purely environmental or social factors. What is required  instead  is  a situational analysis  which  takes  into account,  first,  the objective problem situation, so far as this  can be reconstructed;  second, the way the situation is perceived by  the participants;  and third,  the choices and decisions that they make. The analysis must include the ideas, aims and purposes of  the  actors  because these determine which  features  of  the situation  are  seen as posing the  most  pressing  problem.  For instance  the Good Samaritan and the people who passed by on  the other  side  of the road confronted the same situation  but  they selected different problems from it. And when we come to consider aims,  purposes  and traditions we face the problems that  Popper set out to solve in the Arthur Holly Compton Memorial Lecture and his subsequent papers.

1.Pluralism and the Thesis of the Three Worlds

This section recapitulates the three world theory

2.The Causal Relations Between the Three Worlds

Popper suggested that the mind (world 2) permits indirect interaction between the physical world (1) and the world of ideas. The human mind can “see” tables and chairs, and it can also “see” and “grasp” abstract objects and relationships such as numbers and scientific theories.
“I suggest that one day we will have to revolutionize psychology by looking at the human mind as an organ for interacting with the objects of the third world; for understanding them, contributing to them, participating in them; and for bringing them to bear on the first world.” (156)

3.The Objectivity of the Third World

He argued for the objectivity and the autonomy of the third world, referring to the Stoics as the first to  make the distinction between the objective logical content of our communications and the objects themselves that we are talking about.

4.The Third World as a Man-Made Product

The special feature of Popper’s world 3, contra the Platonic  superhuman and divine realm of forms or ideas, is that it is manmade. The majority of philosophers consider that ideas are manmade but not autonomous; they are not “real” because eternal verities cannot be manmade.

“I suggest that it is possible to accept the reality or the autonomy of the third world, and at the same time to admit that the third world originates as a product of human activity…[it is autonomous, or superhuman because] it transcends its makers.” (159)

The arguments in this section set the scene for the next two sections on understanding (hermeneutics) and the mental processing of the objects in the third realm.

5.The Problem of Understanding

This section begins with the vogue of anti-psychologism initiated by Husserl’s Logische Untersuchungen in 1900 which was probably his reaction to Frege’s criticism of Husserl’s previous study of arithmetic from a psychologistic point of view. However that did not last and the humanities persisted with various theories of subjective or psychological understanding, partly as a reaction against the idea that they should copy the physicists, despite the obvious difference between the humanities and the natural sciences, namely the role of  intentions and plans in social events.

6.Psychological Processes of Thought and the Third World

Here Popper confronted the school of sympathetic understanding or empathy, or the subjective re-enactment of actions described by Collingwood. It has to be said that Colingwood is an excellent antagonist on this point because his method of “question and answer”, starting with the problem that the actor was trying to solve, clearly anticipates some important elements of Popperian situational analysis.

“As against this view my thesis is this. Exactly as a subjective state of understanding finally reached, so a psychological process which leads up to it must be analysed in terms of the third world objects in which it is anchored. In fact it can be analysed only in those terms.
He then used the four-stage problem-solving schema to describe the process of situational analysis that is required to take account of the problem situation and the role of third world elements in defining it and moving on to evaluate alternative the possible solutions.

7.Understanding and Problem-Solving

This section and the two following expand on the theme of problem solving with the use of world three objects. He used two examples, one described as “very trivial” (a mathematical proposition) and the other a “a case of objective historical understanding” namely Galileo’s theory of the tides.

10.The Value of Problems

Here Popper responded to the possible objection that moving the focus from understanding a theory to understanding a problem situation is only shifting the problem, not solving it. The answer is that it is a “progressive problem shift” (a handy term which he attributed to Lakatos) because it leads to more difficult and interesting questions. Moreover this is essentially an active trial and error process.

“Thus my answer to the metaproblem ‘How can we learn to understand a scientific problem?” is: by learning to understand some live problem. And this, I assert, can be done only by trying to solve it, and by failing to solve it.”

11.Understanding (‘Hermeneutics”) in the Humanities

In this section and the next “Comparison with Collingwood’s Method of Subjective Re-Enactment” Popper embarked on a close comparison of his approach with that of the subjective school, notably Dilthey and Collingwood.

Part of the problem arises from the defective view of natural science that Popper subjected to lifelong criticism. Students of the humanities do not usually appreciate the amount of “hermeneutics” involved in the natural sciences, that is the process of conjectural reconstruction of problem situations and testing the possible solutions. That is a far cry from the antiquated textbook process of observation, induction and verification of the results.

“Labouring the difference between science and the humanities has long been a fashion, and has become a bore. The method of problem solving, the method of conjecture and refutation, is practised by both. It is practised in reconstructing a damaged text as well as in constructing a theory of radioactivity.”

Other Reading Guides    The Logic of Scientific Discovery
  ThePoverty of Historicism
  The Open Society and its Enemies
  Conjectures and Refutations

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