Sir Karl Popper

The most important philosopher of science since Francis Bacon (1561-1626),

Sir Karl Popper finally solved the puzzle of scientific method,

Instead of scientific knowledge being discovered and verified by way of

inductive generalizations, leaping from perceptual data into blank minds,

in terms that go back to Aristotle,

Popper realized that science advances instead by deductive falsification

through a process of "conjectures and refutations."

It is imagination and creativity, not induction, that generates real scientific theories,

which is how Einstein could study the universe with no more than a piece of chalk.

Experiment and observation test theories, not produce them.

This was not, in retrospect, so hard to understand; and some philosophers,

like Kant, had come close to recognizing it. It is still subject to some dispute,

though mainly from those who misunderstand the rejection of induction or

who demand positive epistemic reasons for crediting theories that are derived negatively,

by falsification

(see "Criticism of Karl Popper in Anthony O'Hear's

An Introduction to the Philosophy of Science").

That is a reasonable enough demand, but the answer can only

come from deeper philosophical epistemology, not from science or philosophy of science.

That deeper epistemology is, in fact, Friesian.

Since Popper thought that justification works through falsification,

and never through verification, he obviously agreed that such propositions

do not need to be proven in the sense of logical derivation.

It is now common in science to use falsifiability as a criterion

for dismissing theories or claims as parts of science.

Popper's own critique of Marx and Freud as unfalsifiable was a classic study,

and the salutary influence of the principle in discussion of psychics or astrology is occasionally seen.

I admit, again, that the decision to accept a basic statement,

and to be satisfied with it, is causally connected with our experiences -

- especially with our perceptual experiences.

But we do not attempt to justify basic statements by these experiences.

Whether or not there is a causal relation between perceptions and statements or beliefs

is actually irrelevant, and Popper commits a grave error by dwelling on it

. We justify statements about experience byreference to the objec

Karl Popper was both a lifelong student and advocate of Immanuel Kant.

The chapter on Kant within Popper's Conjectures and Refutations (Ch. 7)

is more than enough to prove Popper's admiration.

However, included in this chapter and many of Popper's other works,

he rejects Kant's concept of synthetic a priori knowledge on the grounds

that Kant created an impossible category of unfalsifiable knowledge

There is in fact no other way to justify them except by memory, hearsay, or inference.

Reference is not a causal relationship but a fundamental logical property of concepts

and propositions, as Popper well understands.

The problem with reference to the objects of experience, as Descartes discovered,

was the question of access to those objects. Popper's mistake

, in criticizing the Positivists, was to accept a Positivist, and Empiricist, premise,

that we only have access to perceptions, to contents of the mind,

not to the objects themselves.

Popper misses the Kantian aspect of Friesian theory that immediate knowledge

consists of phenomenal objects, which as objects,

are not merely psychological or subjective.

One's psychological attitude, or its origin, is therefore irrelevant;

and the cognitive force of immediate knowledge lies in the intersubjective availability

of empirical objects, our direct acquaintance with them, and the possibility of

their being shown to others by way of justification.

(These issues are discussed in the essay "Ontological Undecidability.")

Furthermore, Popper himself realized that the test of falsification cannot be applied to everything,

for it is not clear how the principle of falsification itself could be subject to a falsifying test.

If the principle can then be known to be true, there must be some means

of verification for certain things after all.

That must return us to Fries' original considerations.

. All universal propositions, according to Popper, are like conjectures,

in that they are about more things (usually) than are subject to inspection.

This is true. This is also what induction, in its classical meaning since Aristotle, is about:

the derivation of universal propositions from the experience and observation of particulars.

Gardner, at the very least, blurs the distinction between universals and particulars.

Thus, he cites the theory that "there are Earth-sized planets" around other stars .

This may indeed be a scientific theory and a conjecture,

but it is a particular (or an existential) proposition, not a universal.

he term 'fallibilism' generally refers to the theory that no belief

can be so well justified or supported by good evidence and apposite circumstances

that it could not be false. Popper's particular brand of fallibilism is not much different,

except for his emphasis on the justification of beliefs through the scientific method.

Falsificationists (the group of fallibilists to which I belong) believe..

. that they have discovered logical arguments which show

that the programme of the first group [the verificationists]²

cannot be carried out:

that we can never give positive reasons which justify the belief

that a theory is true...

we falsificationists believe that we have also discovered a way to realize

the old ideal of distinguishing rational science from various forms of superstition...

the rationality of science lies not in its habit of appealing to empirical evidence

in support of its dogmas -- astrologers do so too --

but solely in the critical approach: in an attitude which, of course,

involves the critical use, among other arguments, of empirical evidence

(especially in refutations). (Conjectures and Refutations, 310; bold emphasis mine)

Popper explains the rationale for his beliefs.

Fallibilism, for him, is the epistemological doctrine that best explains

how contemporary science provides knowledge without resorting to dogmatic beliefs (i.e. faith)

. All beliefs include falsehoods we may or may not be unaware of,

which renders the quest for certainty impossible.

When we become aware of a false belief, we consequently

become aware of our capability for belief in falsehoods,

and are reminded how much more we have to learn.

Popper's fallibilism can account for why Einstein's replacement of Newtonian Mechanics

stimulated so much progress in physics,

a field that some of his contemporaries had once thought nearly finished.

Popper points to the beginning of World War I,

when even physicists as renowned as Henri Poincaré believed Newton's theory

was true and irrefutable (Conjectures and Refutations, 258).

Fallibilism, for Popper, explains the existence of scientific progress -

the continual discovery of our own ignorance and quest for the truth.

Scientific progress is possible because new theories account for new

(or sometimes, old) empirical evidence, which earlier scientific theories could not.

In this fashion, Popper's fallibilism describes the gradual evolution of knowledge,

where new knowledge is built upon the bedrock of old, falsified knowledge:

It so happens that the real linchpin of my thought about human knowledge

is fallibilism and the critical approach; and that I see...

that human knowledge is a very special case of animal knowledge.

My central idea in the field of animal knowledge (including human knowledge)

is that it is based on inherited knowledge.

It is of the character of unconscious expectations.

It always develops as the result of modification of previous knowledge.

...human knowledge... may be formulated in language, in propositions.

This makes it possible for knowledge to become conscious and

to be objectively criticizable by arguments and by tests.

In this way we arrive at science. Tests are attempted refutations.

All knowledge remains fallible, conjectural.

...we learn by refutations, i.e., by the elimination of errors, by feedback.

(Realism and the Aim of Science, xxxv, bold emphasis mine)

Since humans can only eliminate errors,

Popper believed all knowledge is an approximation to the truth.

In his later years, he coined the term "verisimilitude"

to express the idea of theories with greater (or lesser) degrees

of correspondence with reality (Conjectures and Refutations, 315).

Additionally, in the above passages,

Popper loosely defines "dogma" as a theory or belief accompanied

by an attitude that denies or ignores counter-arguments and refuses criticism,

especially contrary empirical arguments.

Popper contrasts dogmas with "the rationality of science",

which he believes concurs with his fallibilist doctrine.

Thus, any belief considered infallible is a dogmatic belief,

because the dogmatist refuses to allow any possibility of error within his belief.

Even logical truths are fallible to the extent that we may err in judging whether a truth

is analytic or demonstrated to be proof valid.

At first glance, fallibilism would appear to be consistent

with the belief in synthetic a priori knowledge.

A synthetic statement is one that can be denied without contradiction;

an a priori proposition is one that can be justified independently of experience.

It follows that false a priori propositions are necessarily false,

and true a priori propositions are necessarily true.

Analytically true statements, in contrast to synthetic statements,

cannot be denied without contradiction; therefore,

analytic a priori propositions are always necessarily true.

A synthetic a priori statement makes a claim to

the same kind of truth-value as analytic a priori statements (i.e., necessarily true),

but synthetic statements are not true by definition and, for that reason,

they must be demonstrated to be true.

Since synthetic statements must be shown to be true outside of definitional knowledge

(which is analytic), our synthetic knowledge is mediate and subject to error or revision.

Therefore, it would seem that belief in synthetic a priori statements is not inherently dogmatic,

even though their truth value is independent of experience.

So why does Popper reject synthetic a priori statements,

if there is no inherent contradiction between fallibilism and synthetic a priori knowledge?

disguise for induction: