REVIEW
Stefano Gattei
MALACHI H. HACOHEN [2000]:
Karl
Popper – The Formative Years, 1902-1945: Politics and Philosophy in Interwar Vienna,
New York: Cambridge University
Press, cloth £ 35 / US$ 54.95
ISBN: 0 521 47053 6 (hardback)
Stefano Gattei
Università degli Studi di Milano
Milan, Italy
‘[I]t is more interesting to
go on trying to solve problems than to look back on one’s failures’:[1]
these words we find in an incomplete one-page typescript, possibly intended to
introduce Karl Popper’s own intellectual autobiography. Popper subsequently
deleted these words and opted to introduce the history of his intellectual
development with a section on his working experience under Adalbert Pösch–an old master cabinetmaker, the only master mentioned in the book–whose
claims of omniscience taught him how little he knew, and that all he could ever
aspire to was to realize the infinity of his ignorance. More than anyone else, Pösch made him realize his fallibility, and turned Popper into a disciple of
Socrates, the first philosopher to embody the scientific attitude that emphasized criticism and
self-criticism.
However,
the very fact that Popper eventually deleted these words, as well as others,
indicates that he was actually facing several problems. Indeed, Popper’s
published work seems to obscure, rather than illuminate, the intellectual
transformation that he underwent as a young intellectual. He helped the
confusion both by omitting historical signposts from his works in the first
place, and then reconstructing his intellectual autobiography in a manner that
concealed most turns and dead ends. As an intellectual autobiography, his
should be and is the history of his ideas, of how he worked his way from one
philosophical problem to another. Little room is left for personal elements or
the context in which ideas develop. Imposing his mature philosophy upon his
memories, he transformed his intellectual development into a linear
progress–from youth politics to psychology in the Twenties, to the logic of
science in the Thirties, to his work on the open society in the years of World
War II. Viewing science as an adventurous revolutionary project, an uneneded quest for ever growing but never certain knowledge,
he undertook an autobiography in which a sort of rationality of scientific
revolutions dominates the narrative, concealing the plurality of directions in
which his thought developed, the diverse options, the intellectual impasses,
and the decisive turning points.
Hacohen’s declared intention is to rectify the life that Popper himself distorted,
calling on contexts that Popper ignored–above all, the ethos of the assimilated
Jewish intelligentsia of Vienna of the time. His aim is not only to provide a
fuller and more accurate account and to recover a rich culture that vanished
(partly into exile, partly up Auschwitz’s chimneys), but also to rescue the young Popper for the present, to see how the
adventurous progressive socialist who revolutionized the philosophy of science and formed a compelling
vision of the open society can help us rethink our problems today, in the
post-Cold War era.
Combining extensive study
of the historical and cultural context, detailed archival research and
engagement of Popper’s politics and philosophy, Hacohen’s book is a major contribution to the understanding of
a central figure of twentieth century philosophy, both as a man and as a
thinker. It traces the formation of Popper’s philosophy, providing a splendid
account of the fin-de-siècle and interwar Viennese milieus. Most notably, he shows how the political and
philosophical dilemmas of Vienna 1900 are still with us, and offers Popper’s
solutions as an alternative to poststructuralists’ ones.
The
book is not directed primarily to Popper’s followers. Nor does Hacohen want to redress the current
political imbalance in the reception of Popper’s work. He openly takes
exception to the uses to which the political right–in Austria, no less–has put
Popper. In the late Sixties and early Seventies Popper actually became, on
account of his critique of Marx and the confrontation with LSE students
(secluded in Penn, Buckinghamshire, he never fully understood the events) the
establishment philosopher par excellence–as
his most recalcitrant pupil, Paul Feyerabend, described him: ‘the established
Sir Karl of later years’.[2]
The purpose of the book is to reverse Popper’s absorption into right-wing
discourse in the postwar years,
and claim him for new progressive politics. Recovering the historical Popper,
whether the committed young socialist or the old, more conservative Popper, who
remained supportive of the welfare state, is certainly the best antidote to the
political misappropriation of his work. Therefore, Hacohen intends primarily to
address the academic left, that has been, in his view, ‘on the wrong track
since it took the postructuralist turn in the late 1970s. I hope to convince them that Popper saw more
clearly than they have through the philosophical and political problems
preoccupying them and that he provides a more promising direction in the search
for answers. In short, I hope that Popper can help the academic left set a new
progressive liberal agenda that will seek to recoup the social losses of the
last two decades’ (p. 2).[3]
Popper
would probably have objected to much of Hacohen’s work: he always did his best to control his public
image and shape his reputation, fighting others’ efforts to reconstruct his
intellectual history that did not fit his own reconstruction. Moreover, he
always insisted–and rightly so, of course–that the origins of ideas have
nothing to do with their validity: what counts is intersubjective criticism, not freedom from prejudices. Hacohen
rightly claims to be extending his method, not challenging it: questions of
genesis are not theoretically trivial, and are especially welcome when they
encourage and facilitate criticism.
But
for an ‘Epilogue’, briefly describing the postwar years, Hacohen stops his reconstruction in early
1946, when Popper and his wife arrived in Britain, with the Gombrichs waiting for them at the docks, presenting him with one
of the first printed copies of The Open
Society and Its Enemies. From Hacohen’s point of view, in his later years Popper certainly advanced new ideas, like the propensity interpretation of probability,
evolutionary epistemology and World 3; also, his philosophy of science became
more thoroughly nonfoundationist and antideterminist. But, whereas the young Popper was open to new influences, willing to
adapt and change, the old Popper focused on developing an already established
philosophy, the sources of innovation almost all internal.
This
is questionable. Popper’s arguments on the topics of realism, indeterminism, propensities, World 3, mind and self, constitute a distinctive metaphysical phase in his
thought–beginning in the Fifities, about twenty years after
the ‘philosophical breakthrough’ described by Hacohen, and developed in close
co-operation with Joseph Agassi (and John Watkins). Epistemological and methodological matters, together with political and
ethical concerns, are now considered within the context of the problem of cosmology, which Popper draws from the Presocratics: ‘the problem
of understanding the world–including ourselves, and our knowledge, as part of
the world’.[4]
Hacohen
suggests that it is the politics and intellectual engagement of the young
Popper that is most relevant today, and it alone can shed light upon the
formation of the philosophy that flourished in postwar years. As he did in his PhD dissertation (The Making of the Open Society, 1993),
Hacohen primarily focuses on Popper’s two basic texts of his political
philosophy, The Open Society and Its
Enemies and The Poverty of
Historicism, showing how they make little sense when read in the cold war
context, due to the disjunction between the German-Austrian milieu, in which
they were formed, and the Anglo-Saxon world, where they became popular after
World War II. It was Red Vienna, not Soviet
communism, that provided the grounds for his critique of Marx. When writing The Open Society and Its Enemies, he
thought fascism reflected a primeval urge to return to the closed ‘tribal’
society, and Marxist mistakes prevented the working class from resisting
effectively the fascist assault on democracy.
Let
me focus here on what I take to be the crucial years for Popper’s intellectual
development: 1929-1934. In his 1929 thesis on axiomatics in geometry (Axiome, Definitionen und Postulate der Geometrie),
he first formulated the problem of
scientific rationality and turned from cognitive psychology to methodology.
These were his first steps into the Vienna Circle’s orbit: he read avidly the
Circle’s works as they were coming out, and soon realized that his deductivism provided a corrective to the Circle’s views.
Therefore, he sought to develop it into an alternative. He formulated the problem of induction and made it the centre of his critique of logical
positivism. The Circle, he argued, failed to solve the problem; his deductivism succeeded. In 1930-1932, working on Die beiden Grundprobleme der Erkenntnistheorie, he discovered demarcation: induction dissolved into demarcation, thus
shifting the focus of Popper’s revolution. As falsifiability moved from margins to the centre, the hypothetical character of science became evident. Returning to the
foundation debate in the Fries-Nelson tradition, he extensively rewrote his
earlier critique of Kant and Fries, formulating a new vision of science as ‘a deductive science that was empirical but not
inductive, testable and confirmable but not certain, demarcated from metaphysics by falsifiability but not deeming metaphysics meaningless. Science left space for
epistemology, methodology, and “non-scientific” philosophy’ (p. 199).
Critical
dialogue with logical positivism propelled Popper’s revolution from the
beginning. He used to work in virtual isolation, withdrawing into seclusion for
lengthy periods, then reappeared to confront the Circle with new ideas. Circle
members were, at intervals, a source of critical feedback that led him to
crucial developments. He did not accept their challenges but, rather, worked out
innovative responses. Though they were a crucial context for his philosophy,
Popper’s differences with the Circle were significant. Hacohen takes exception
to those historians who have tended to accept the Circle’s contention that
Popper exaggerated his disagreements with positivism. Popper’s critique sprang from a marginal Kantian perspective foreign to logical positivism. The
movement regarded it as a contribution to their own scientific philosophy. He
vainly protested, insisting that his critique was deadly. The movement failed
to grasp the fundamental difference between decision and justification, thus
never recognizing the significance of Popper’s critique–as the persisting ‘official’
history of the demise of the movement still testifies. According to this
stereotypical history, Popper was a minor logical positivist who introduced falsifiability as a criterion of meaning and exaggerated his
difference from Carnap and from Neurath. As Hacohen clearly shows, this is a convenient history, which rests on an emphasis on certain aspects and
criticisms of logical positivism at the expense of an oversight of other
aspects. The demise of logical positivism never took place; but a deadly
criticism of it was offered already in the early Thirties by Popper.[5]
Surely,
his relationship to the movement was problematic: he developed his philosophy
in dialogue with theirs, but he refused to take the linguistic turn: ‘he understood it perfectly, but, rather than take the turn, he found a
way to cross the junction, forging his way straight ahead’ (p. 209). He admired the early work of Schlick, and took courses
under him; he studied Wittgenstein, Hahn and Carnap, also visiting the latter’s seminars, but he was no
logical positivist. Therefore, he can not be placed within the spectrum of
opinions on various issues in the Circle–since that would amount to an
oversight of the different problem situations underlying the disagreements. Popper upheld Kant against Wittgenstein and the Vienna Circle: even
though Kant did not have the right answers, he was on the right track to
discover better ones, whereas the attack on Western metaphysics manifested old
philosophical absolutism and would lead to a dead-end. He pursued a reform of
metaphysics, not its overthrow. He regarded himself as an heterodox Kantian, and the positivists as precritical. He was developing an alternative to positivism, seeking to redirect
the philosophy of science away from language to problems.
Nonetheless,
collaboration between Popper and the Circle did take place. Most Circle members
proved remarkably receptive to their critic: practicing the intellectual
openness that Popper only preached, the Circle gave him the chance to develop
and articulate the most compelling philosophy emerging from the interwar Viennese milieu. In this sense, Popper was the true heir of the Vienna
Circle’s legacy. Both he and they reformulated and reinforced their positions
in response to mutual criticism. Two philosophies were in dialogue. The Circle
denied that there were two, and some of its official heirs still do. Popper,
they claimed, belonged to their movement. Not so. Mutual misunderstandings,
Popper’s exile to New Zealand and the delay with which his books were
eventually published (The Logic of
Scientific Discovery, the English translation of Logik der Forschung, saw the
light in 1959, while Die beiden Grundprobleme appeared only twenty years later, and it has not yet been translated
into English) created a distortion of Popper’s philosophy for the next
generation. The ‘legend’ of a positivist Popper had emerged.
The
philosophical breakthrough of 1930-1932 was completed in the following two
years with Logik der
Forschung (which got published in November 1934): after drawing a new vision of science and philosophy, Popper developed
an innovative methodology to support his vision, applying it to probability and
quantum physics. Die beiden Grundprobleme analyzed the correspondence between epistemology and scientific
practice. Logik completed the shift: setting the rules of science, methodology is
prescriptive, not descriptive; induction, whether used in practice or not, is
invalid. Popper’s demarcation was better than
that advanced by the Circle’s members not just because it corresponded to
scientific practice, but also because it clarified
and resolved its problems.
Taking Fries’s and Nelson’s demonstration of endless regress in epistemology as a
point of departure, Popper nonetheless defended epistemology, though without
attempts at grounding knowledge: epistemology’s task was not to justify
statements, but to investigate methods and criticize procedures, pointing out
contradictions and misappropriations. It sought to clarify, criticize and
improve practice, not to ground it.
Faced with
Fries’s trilemma–dogmatism, infinite regress, or psychologism–he gave up the idea that justification is a necessary condition for
scientific knowledge: our scientific knowledge can not and need not be
justified. His was a revolutionary solution. Testing had no natural end point;
a decision to stop and accept a statement was conventional, and such an
acceptance was dogmatic, in a sense, but it was an undangerous dogmatism: when doubts emerged,
scientists renewed testing. Subjective convictions contributed to the consensus
that ended testing–but, again, this was harmless: scientists did not ground
statements, and though they accepted them in accordance with an objective methodological rule, stipulating admission of
confirmed test statements into science, these rules were not so strict as to
impose unique moves in all situations, and allowed for moves that led to the
upholding of errors. ‘Dogmatism, endless regress, and psychologism all played roles in scientific work, but they were rendered innocuous
by science’s hypothetical, falsifiable character’ (p. 230). Science progressed not by discovering unshakable
truths, but by eliminating errors: change was its hallmark, and intersubjectivity (that is, Kant’s surrogate
for objectivity) was the sole basic rule. And though it was no guarantor of
progress, it was what kept the scientific enterprise continue to progress thus
far. As long as science progresses, research may continue. Convention and
experience modified, rather than determined, each other. Corroboration was an
assessment of how well a theory stood up to tests: it represented a rough
estimate that had no truth value or probability value. Theory informed all
action and decision, and decision can not be justified. Tarski enabled Popper to speak about correspondence of a statement and a
‘fact’ in one language, thus relegitimizing ‘commonsense’ truth. Experience and access to reality remained
problematic, but it was possible to learn from it all the same. There was no
way of knowing for sure what the facts were, and whether a statement actually
corresponded to them. Truth (i.e.
correspondence) was an ideal, a regulative idea, always sought and never sure
to have obtained: indeed, we may well obtain truth, but not justified certainty
that we have obtained it. The linguistic turn no longer threatened realist
metaphysics and objective science. Rationality required no foundation, only
critical dialogue: it was the end of foundationist philosophy.
While
Popper was accomplishing his methodological revolution, prolonged tensions
within the Circle broke into the open with the ‘protocol sentences debate’ in
the pages of Erkenntnis
(1934, summer and fall issues). Popper was initially
oblivious to the debate. Neurath eventually directed him to the exchange, which
provided him with new ammunition for his attack on positivist psychologism and subjectivism. Taking issue with the literature re-evaluating Otto
Neurath and his legacy, Hacohen sheds new light on the relationship between
Popper and Neurath, and also expresses his discontent with the current state of
the debate on interwar Viennese
philosophy of science. In his discussion of the Popper-Neurath exchange Hacohen
illustrates his views on the role and task of the historian’s work, as well as
on the lesson to be learned from his account: ‘if the past is to inform rather
then vindicate the present, its alterity must be preserved’ (p. 262).
Neurath’s review of Logik brought out the sharp contrast between protocols and
falsification, the positivist-physicalist and critical Kantian programmes for philosophical reform. Though Carnap
and Schlick were convinced that Popper was of their own persuasion (and Popper
feared that Carnap’s
‘official’ favourable review of Logik, once again assimilating him into positivism, would
have diminished his revolutionary contribution), Neurath disagreed. To him,
alone among the Circle, Popper was positivism’s nemesis, the Circle’s ‘official opposition’. He clashed with Popper in the Paris and Copenhagen congresses, in 1935
and 1936. Then Popper went to his New Zealand exile, and virtually disappeared,
out of touch and influence. Neurath, however, did not relent, fighting the
legend of a ‘positivist Popper’ till his premature death in London, in 1945,
left the legend contrasted by Popper alone in the postwar years.
Neurath
shared with Popper a wide range of assumptions: with him, Neurath was
epistemologically closer than any other Circle member. Both insisted that
language could not be compared with reality and sought a way to bridge the gap
between experience and language, so that experience informed scientific theory;
both believed that observations are theory-laden and regarded them as
provisional. Popper kept science and reality separate, yet allowing experience
to arbitrate theoretical questions through a decision, logically and
methodologically informed, to accept a falsifying statement. By contrast, Neurath’s linguistic protocols proved ineffective: hostage of the prison house of language, his
attempt to translate psychological behaviour into physicalist language (as Carnap did) reached nowhere.[6]
Metaphysical disagreement underlaid the Neurath-Popper exchange.
Missing
the nonfoundationism of
his philosophy, scholars accord Popper a rough treatment. Those sharing his
views have been unsuccessful in defending him because they are unwilling to
engage poststructuralism
(and some of those who do, like Noretta Koertge, end up
defending scientific rationality in a manner that Popper could have found
objectionable). In a new way, focusing on the foundation and protocol sentences
debates of the mid-Thirties, Hacohen shows how ‘Popper provided the most viable
response to “poststructuralist” dilemmas among the disputants: a modified conventionalist, nonfoundationist philosophy that safeguarded rationalism, but skirted
the dangers of absolutism’ (p. 263).
In
his later years, Popper spoke nostalgically of Habsburg (and classical Athenian) multiculturalism, praising
culture clash as productive of great intellectual advances. In his view,
culture clash allowed for critical dialogue, that transformed identities,
transgressed boundaries and changed communities. But, Hacohen argues, ‘Popper
underestimated the difficulty of creating a situation that would make such a
dialogue possible. Culture clash under conditions of unequal power does not
always create dialogue, or advance cosmopolitanism. It may result in
oppression’ (p. 541). To him, Popper’s irrational commitment to rationalism,
which constitutes his precondition to dialogue, is insufficient, since for an
ideal speech situation power must be neutralized, so that it has minimal influence on dialogue:
‘socially disadvantaged groups do not have a fair chance of being heard, let
alone prevail, in the so-called democratic political process’ (p. 543). It is
difficult to reason over differences, he continues, especially ethnic and
religious ones. The culture of debate, promoted by Popper in his seminars and
writings, is ill suited to intercultural and political dialogue. ‘Participants
in debate must recognize others as equal, make a genuine effort to listen, understand, and learn,
and attempt to reach agreement and compromise. […] Only in a deliberative
democracy (or the Open Society) are intersubjective criticism and politics proximate. We do not yet live
in such a democracy, and if we ever come close, there will be communities that
do not accept intersubjective criticism’ (p. 545). In other words, though liberal communicative
ideals and Popper’s rationality criterion tell us where we should head, they
provide no guidelines for evaluating political proposals. ‘If critical rationalism
is to remain politically vital, not merely a regulative ideal for a utopian
cosmopolitan age, Popperians
need to develop guidelines for political evaluation’ (p. 546).
Hacohen
makes a point here, challenging all Popperians to a rejoinder (and I take myself to be one). He is right: Popper did
not suggest how we might proceed in situations that do not allow for an open
dialogue and admit of intersubjective criticism. But did Popper promise to solve a problem here that he did
not? As a matter of fact, it is precisely looking back to Popper’s youth years,
through the very new spectacles Hacohen’s impressive reconstruction provides us with now, that we understand the
true conditio sine qua
non of his lifelong intellectual quest.
A
radical choice is the origin of the whole of Popper’s philosophy–a decision
exemplified best in an early encounter with a Nazi youth, who refused to argue
and said Popper: ‘What, you want to argue? I don’t argue: I shoot!’.[7]
He was confronted with an alternative, and built the entire edifice of his
philosophy on the decision to choose for dialogue, to fight with words instead
of swords, to let our theories die in our stead. Of course, this marks a
difference between the rules obtaining in the ideal scientific and political
communities: philosophers and scientists can (and actually must) experiment
with ideas, while politics should not likewise experiment with human lives.
Still, critical rationalism identifies with Popper’s humanism, since
rationality is not so much a property of knowledge as a task for humans.
According to Popper, rationality is inscribed within the framework of a more
basic and general rationality, the rationality of the world and of the human
person. Popper sees the rational attitude as a moral obligation against scientific
dogmatism and irrationalism, and as a clear option against violence. It is an attitude of dialogue,
accepted with the full awareness of the difficulty of such a task.
It
is, of course, an expression of faith–a faith in peace, humanity, freedom and
intellectual modesty, and in the possibilities of critical discussion: it is an
appeal to reason, and ‘reason also is choice’, as John Milton put it.[8]
William Bartley tried to show that such an irrational commitment was
unnecessary, an unnecessary concession to irrationalism: if someone does not want to engage in a dialogue and
shoot, then there is anyway nothing, of course, Popper (or others) can do about
it. And, as Bartley added, Popper was still not ready to propose a fully non-justificationist agenda, as he should. Popper did acknowledge that
Bartley alerted him to the extent of his non-justificationism and to the fact that this was the aspect of his
philosophy that made his logical-positivist peers so hard to take his ideas as
seriously as they deserve. However, it is precisely such an irrational
commitment that gave rise to Popper’s philosophy.[9]
To him, dialogue was a value. All life is problem solving: problems arise
together with life, and there are problems only when there are values. When
violence wins over peaceful debate, reason must give in. As Popper said in his
later years, ‘we should not shrink from waging war for peace’:[10]
we have to fight to establish the minimal conditions for critical exchange.
Toleration allows differences to exist; respect means willingness to learn from
them. Toleration and respect are obligatory, not criticism. We do not have to
try to make people critically minded: we have no right to force them to offer
or accept criticism, nor to learn to participate effectively in the game of
critical discussion. It is in their right to refuse to do so. All we can (and
have to) do is to try to help them become critically minded if and when they
request that. Following the road of reasonableness and taking other people
seriously, i.e. respecting their
freedom, is far more important than persuading them. Popper’s methodological
proposals reflect both hope that rational debate will lead to improvement, and
the conviction that criticism entails responsibility. Such responsibility can
be encouraged, but not forced.
The
problem of rationality is the most important of philosophical problems and, in
a sense, the core of philosophy itself. It concerns the choice of one’s
principles and values, says Popper. As Joseph Agassi put it, it concerns the
choice of one’s lifestyle. The solution to the problem of rationality is the
very starting point of every philosophical approach, the very choice of one’s
lifestyle. Popper’s approach to philosophy is his solution to the problem of
rationality. His life is the very embodiment of his understanding of
rationality and his solution to its fundamental problem.
In
Popper’s view there are two natural coalitions: between determinism and inductivism, on the one hand, and between indeterminism and fallibilism, on the other. He clearly chooses the latter. As John
Watkins noticed, in the closing lines of his contribution to the two volumes on
The Philosophy of Karl Popper,
‘learning about the world means, on the first view, being conditioned by it; on
the second view, it means adventuring within it’.[11]
It is not simply an intellectual affair or a matter of taste: without the
possibility of self-governing, life and the quest for knowledge would be
nothing but farces. Popper believed in an ‘open universe’ and theorized that, in
science as well as in politics, free and responsible choice is a moral
decision. This makes the balance achieved by Popper’s thought unsteady–but
unsteadiness is the condition for life. Firmly committed to hard work, he spent
his whole life struggling with problems, failing as often as succeeding. His
was the intellectual quest of a twentieth century Sysiphus–a Sysiphus who, unlike that described by Albert Camus, in the unending struggle with problems and not
condemned to repetition, managed to be happy, achieving progress till the end.
[1] Fragments of the Autobiography, Karl Popper Archives
(134,34).
[2] Paul K.
Feyerabend, Science in a Free Society,
London: New Left Books, 1978, p. 115.
[3] All page
references are to Hacohen (2000).
[4] Karl R. Popper, ‘Preface
to the English Edition, 1958’ to The
Logic of Scientific Discovery (London: Hutchinson, 1959), p. 15; see also
the three volumes of the Postscript,
in particular The Open Universe. An
Argument for Indeterminism (London: Hutchinson, 1982), chapter IV and
‘Addendum 1’; and Quantum Theory and the
Schism in Physics (London: Hutchinson, 1982), p. 1 and chapter IV.
[5]
Denying all that amounts to a distortion of history for political purposes, not
to a rational reconstruction offered for intellectual ones: see my review of
Michael Friedman, Reconsidering Logical
Positivism (Cambridge: Cambridge University Press, 1999), Newsletter of The History of Philosophy of
Science (HOPOS) Working Group, vol. 5, no. 2, spring-summer 2000, pp. 18-19.
It is not simply a matter of priority. It is a matter of intellectual honesty.
We might like or dislike Popper’s philosophy but, as scholars, philosophers or
historians, we would better confront his ideas: the best way to express
disagreement is not ignoring ideas, but criticizing them–as most of Popper’s
closer pupils and disciples did.
[6] Neurath’s interpreters
believe that the charge of psychologism is a distortion
by Popper. I find their arguments unconvincing, and Hacohen himself thinks they
are problematic.
[7] Karl R. Popper, The Myth of the Framework. In Defence of
Science and Rationality, London and New York: Routledge, 1994, p. XIII.
[8] John Milton, Paradise
Lost, 1674, Book III, 108.
[9] As Hacohen
remarks, ‘Bartley wisely disposed of the justificationist ladder once he had seen the world aright’ (p. 519).
See also my ‘The Ethical Nature of Karl Popper’s Solution to the Problem of
Rationality’, Philosophy of the Social
Sciences, 2001, in press.
[10] Karl R. Popper, All Life is
Problem Solving, London and New York: Routledge, 1999, p. 119.
[11] John W. N.
Watkins, ‘The Unity of Popper’s Thought’, in Paul A. Schilpp (ed.),
The Philosophy of Karl Popper, La Salle, Illinois: Open Court, 1974,
pp. 371-412; the quotation is from p. 407.