There are two reasons for the popularity of an idea. The idea has either survived criticism and is accepted by people because of its usefulness; or it has replicated among idea holders in a culture by disabling their critical faculties.

There is no reason to think that an idea which has survived all criticism and which remains our best explanation on a subject today could not be superseded by another theory tomorrow.

All knowledge is conjectural. There is no authority on what is known or what can be known and the popularity of an idea is not a proof of its truth.

Progress happens by conjecture and criticism. When a culture shields its ideas from criticism, it fails to error-correct them. No culture collapsed because it focused on error-correcting its ideas too much. The parochial answer for why a society collapsed could be “because of the weather” but the deeper explanation for its ruin is a lack of knowledge.

The Enlightenment created a different kind of tradition; a tradition which thrived on its ideas being criticized—a tradition of criticism. By seeking good explanations, we were able to explain and command the physical world, resulting in the rapid progress that characterizes the modern-day world.

The weekly roundup

1. Sarah Fitz-Claridge on Is it necessary to reject authority?

2. A lovely gift of ideas for David Deutsch’s 70th birthday.

3. Mark Cuban on Twitter and free speech.

4. Karl Popper on the critical rationalist attitude:

“We must therefore neither revere nor revile religion as such, or philosophy as such. Rather, we must evaluate religious and philosophical ideas with critical and selective minds. The terrifying power of ideas burdens all of us with grave responsibilities. We must not accept or refuse them unthinkingly. We must judge them critically.”

— Karl Popper, The Myth of the Framework: In Defence of Science and Rationality

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