If you can't say it simply and clearly, keep quiet, and keep working on it till you can.
The growth of our knowledge is the result of a process closely resembling what Darwin called 'natural selection'; that is, the natural selection of hypotheses: our knowledge consists, at every moment, of those hypotheses which have shown their (comparative) fitness by surviving so far in their struggle for existence, a competitive struggle which eliminates those hypotheses which are unfit.
Interpretation
What this quote means
Knowledge evolves through the survival of the fittest hypotheses, much like natural selection.
This quote articulates the idea that our understanding of the world develops through a process akin to natural selection. Just as species that are better suited to their environments thrive while others fade away, so too do hypotheses that demonstrate greater explanatory power and effectiveness persist, while less viable ideas are discarded. This underlines the importance of critical thinking and scientific inquiry in the pursuit of knowledge, suggesting that what we accept as truth is always open to challenge and revision.
Themes
In practice
Example use cases
In a lecture on scientific methods, you could use this quote to illustrate the rigorous testing of ideas.
More from Karl Popper
All quotes →No particular theory may ever be regarded as absolutely certain.... No scientific theory is sacrosanct.
The belief in a political Utopia is especially dangerous. This is possibly connected with the fact that the search for a better world, like the investigation of our environment, is (if I am correct) one of the oldest and most important of all the instincts.
A rationalist is simply someone for whom it is more important to learn than to be proved right; someone who is willing to learn from others - not by simply taking over another's opinions, but by gladly allowing others to criticize his ideas and by gladly criticizing the ideas of others
Thus science must begin with myths, and with the criticism of myths; neither with the collection of observations, nor with the invention of experiments, but with the critical discussion of myths, and of magical techniques and practices.
I am opposed to looking upon logic as a kind of game. ... One might think that it is a matter of choice or convention which logic one adopts. I disagree with this view.
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Everything in the world is beautiful, but Man only recognizes beauty if he sees it either seldom or from afar. Listen, today we are gods! Our blue shadows are enormous! We move in a gigantic, joyful world!
They were watching, out there past men's knowing, where stars are drowning and whales ferry their vast souls through the black and seamless sea.
Forced to choose between limiting population or trying to increase food production, we chose the latter and ended up with starvation, warfare, and tyranny.
I became insane, with long intervals of horrible sanity.
It was a good thing to have a couple of thousand people all rigid and frozen together, in the palm of one's hand.
And if these incidents now seem full of significance and all of a piece, it's probably because I'm looking at them in the light of what came later.