Conjectures and Refutations

This is a great book by Karl Popper; you should read it. You can even do that online as rosenfels.org/Popper.pdf. The overall theme is the title; he explains it well in the preface:

... a theory of reason that assigns to rational arguments the... role of criticizing our often mistaken attempts to solve our problems. And it is a theory of experience that assigns to our observations the... role of tests which may help us in the discovery of our mistakes. Though it stresses our fallibility it does not resign itself to scepticism, for it also stresses the fact that knowledge can grow, and that science can progress - just because we can learn from our mistakes.

The way in which knowledge progresses, and especially our scientific knowledge, is by... conjectures... controlled by... attempted refutations, which include severely critical tests. They may survive these tests; but they can never be positively justified: they can neither be established as certainly true... Criticism of our conjectures is of decisive importance: by bringing out our mistakes it makes us understand the difficulties of the problem which we are trying to solve. This is how we become better acquainted with our problem, and able to propose more mature solutions: the very refutation of a theory... is always a step forward that takes us nearer to the truth. And this is how we can learn from our mistakes.

As we learn from our mistakes our knowledge grows, even though we may never know that is, know for certain. Since our knowledge can grow, there can be no reason here for despair of reason. And since we can never know for certain, there can be no authority here for any claim to authority...

Those among our theories which turn out to be highly resistant to criticism... may be described, together with the reports of their tests, as 'the science' of that time. Since none of them can be positively justified, it is essentially their critical and progressive character - the fact that we can argue about their claim to solve our problems better than their competitors - which constitutes the rationality of science.

Popper's work is dense, which makes summarising it difficult; I contrast that with The Righteous Mind, or fluff like The Tyranny of Merit which is easy to review. I really do recommend that you read him yourself. I will content myself with pulling out some pieces. FWIW, I agree with essentially all that Popper says. Having sat on this post for a bit, I think I shall let it out into the world with only the first two sections covered; I may get round to the rest later.

Introduction: On the Sources of Knowledge and of Ignorance 

Popper's main objectives in this tome are scientific but it turns out that politics gets mixed in: The belief of a liberal... in the possibility of a rule of law, of equal justice, of fundamental rights, and a free society - can easily survive the recognition that judges are not omniscient and may make mistakes about facts and that, in practice, absolute justice is hardly ever realized in any particular legal case. But this belief... can hardly survive the acceptance of an epistemology which teaches that there are no objective facts... and that the judge cannot have made a factual mistake because he can no more be wrong about the facts than he can be right. And we agree that there are objective facts (see-also my review of Why Materialism is Baloney).

There is a view - which Popper attributes to the the Renaissance, to Bacon and Descartes - that truth is manifest¹. Not that it is easy to see, but that once it is declared, it can be seen to be true. Thus there is no need for authority; although this isn't really true: Descartes has God as his authority, Bacon has Nature. This he regards as an optimistic doctrine; its opposite is a lack of belief in human reason, which demands an unliberal authority. But if you adopt the optimistic view, you need a theory of error or ignorance to explain why this manifest truth is not believed; and this is often a conspiracy view: priests² or capitalists or whatever conspire to confuse the good folk; or in a worse case, fanatics insist you must be evil if you cannot see their truth. But all this is not necessary, because the doctrine is false: truth is not manifest; it is hard to come by and easy to lose.

Another tempting source of authority is definitions. But considered carefully, we realise that definitions never provide factual knowledge of the world.

Popper again finding congruence between the political and the epistemic: The traditional systems of epistemology may be said to result from yes-answers or no-answers to questions about the sources of knowledge. They never challenge these questions [but] these questions are clearly authoritarian in spirit. They can be compared with that traditional question of political theory, 'Who should rule?', which begs for an authoritarian answer such as 'the best', or 'the wisest'... It should be replaced by a completely different question such as 'How can we organize our political institutions so that bad or incompetent rulers... cannot do too much damage?'... The question about the sources of our knowledge can be replaced in a similar way... I propose to assume, instead, that no such ideal sources exist... to replace, therefore, the question of the sources of our knowledge by the entirely different question: 'How can we hope to detect and eliminate error?' The question of the sources of our knowledge, like so many authoritarian questions, is a genetic one. It asks for the origin of our knowledge, in the belief that knowledge may legitimize itself by its pedigree... The proper answer to my question [is] 'By criticizing the theories or guesses of others and - if we can train ourselves to do so -by criticizing our own theories or guesses.'

Science: Conjectures and Refutations

Popper begins his considerations of what makes a theory scientific with his usual examples: relativity, psycho-analysis, and the Marxist theory of history. And finds the latter two lacking, in that they are able to accomodate anything: they cannot be falsified; there is nothing that they rule out³.

Popper solves the Humean problem of induction by discovering that scientific theories are not deduced by induction from observations; rather they are conjectures that are tested by attempted refutations. This is both charming and correct. A theory is any old wild-eyed idea⁵; a scientific theory is one open to refutation by some conceivable experiment. The antient Greek's "planetary orbits are perfect circles because circles are perfect and the heavens are perfect" was a theory; the simple version was gradually falsified by observations and grew epicycles; these too were eventually contradicted by observations. Along the dark centuries the theory lost most of its scientific character by fossilising into dogma and being resistant to criticism; eventually this crumbled. But Kepler's ellipses were not "deduced" from observations; instead, they were the last thing he tried after a long series of other guesses were falsified by observations⁴.

There may be - this is my thought, not Popper's - some relation here to Kuhn's ideas in The Structure of Scientific Revolutions. Wherein "normal" science does look rather like the process of finding lots of observations that concur with existing theories; only tiny amount of work is paradigm-shifting, the finding of new wild-eyed ideas.

Popper rather wistfully notes that the problem of induction is solved. But nothing seems less wanted than a simple solution to an age-old philosophical problem. And that rings true; philosophy has lost heart, and is more interested in endless talk around old problems, and commentary on what others wrote, and endlessly recursive commentary-on-commentary, than it is on solutions.

Notes

1. I'm a touch dubious about this myself; in Descartes case, he needs the "anything clearly and distinctly perceived is true" to get him out of his pit of doubt; see-also my scathing review. And as for Bacon, where in Popper's view the "authority" guaranteeing correctness is Nature rather than God, see here.

2. See-also Hobbes: Of the Kingdom of Darkness.

3. Or, in the Marxist case, the original version had been falsified by experience but the theory proved sufficiiently flexible to evade this.

4. Incidentally... nowadays, we of course think of planetary positions in 3-D, and we have observations of wondrous accuracy. But in those days all they had were angular bearings from a moving platform, viz the Earth; even had you thought of it you couldn't just plot them out and go "oh yeah, that's an ellipse". And sweeping out equal areas in equal times is similar: this too was a conjecture, which wasn't falsified.

5. This I think leads to Popper being more generous that I would be to a number of the Antient Greek ideas. See-also Après ma mort, je ferai tomber une pluie de roses

Refs

* Science.

* Why do people believe true things?