Quotes from David Deutsch

Although, through the vagaries of international politics, Athens became independent and democratic again soon afterwards, and continued for several generations to produce art, literature and philosophy, it was never again host to rapid, open-ended progress. It became unexceptional. Why? I guess that its optimism was gone.

The most important of all limitations on knowledge – creation is that we cannot prophecy: we cannot predict the content of ideas yet to be created, or their effects. This limitation is not only consistent with the unlimited growth of knowledge, it is entailed by it.

SOCRATES: No, I am not sure of anything. I never have been. But the god explained to me why that must be so, starting with the fallibility of the human mind and the unreliability of sensory experience.

Science is what we have learned about how to keep from fooling ourselves.' By

But in any case, understanding is one of the higher functions of the human mind and brain, and a unique one. Many other physical systems, such as animals' brains, computers and other machines, can assimilate facts and act upon them. But at present we know of nothing that is capable of understanding an explanation – or of wanting one in the first place – other than a human mind.

Because we are universal explainers, we are not simply obeying our genes. For

We never know any data before interpreting it through theories. All observations are, as Popper put it, theory-laden,* and hence fallible, as all our theories are. Consider

Amending the 'data', or rejecting some as erroneous, is a frequent concomitant of scientific discovery, and the crucial 'data' cannot even be obtained until theory tells us what to look for and how and why.

An optimistic civilization is open and not afraid to innovate, and is based on traditions of criticism.

a rational political system makes it as easy as possible to detect, and persuade others, that a leader or policy is bad, and to remove them without violence if they are.

systems of government are to be judged not for their prophetic ability to choose and install good leaders and policies, but for their ability to remove bad ones that are already there.

Trying to rely on the sheer good luck of avoiding bad outcomes indefinitely would simply guarantee that we would eventually fail without the means of recovering.

If something is permitted by the laws of physics, then the only thing that can prevent it from being technologically possible is not knowing how.

Perhaps a more practical way of stressing the same truth would be to frame the growth of knowledge (all knowledge, not only scientific) as a continual transition from problems to better problems, rather than from problems to solutions or from theories to better theories. This

The most general way of stating the central assertion of the neo-Darwinian theory of evolution is that a population of replicators subject to variation (for instance by imperfect copying) will be taken over by those variants that are better than their rivals at causing themselves to be replicated. This

Using our explanations, we 'see' right through the behaviour to the meaning. Parrots copy distinctive sounds; apes copy purposeful movements of a certain limited class. But humans do not especially copy any behaviour. They use conjecture, criticism and experiment to create good explanations of the meaning of things – other people's behaviour, their own, and that of the world in general. That

Those two overarching concerns are these: we Athenians are concerned above all with improvement; the Spartans seek only – stasis. Two opposite objectives. If

a population of replicators subject to variation (for instance by imperfect copying) will be taken over by those variants that are better than their rivals at causing themselves to be replicated.

Whenever we observe anything – a scientific instrument or a galaxy or a human being – what we are actually seeing is a single-universe perspective on a larger object that extends some way into other universes. In

Copenhagen interpretation Niels Bohr's combination of instrumentalism, anthropocentrism and studied ambiguity, used to avoid understanding quantum theory as being about reality.

mechanical reinterpretations of human affairs not only lack explanatory power, they are morally wrong as well, for in effect they deny the humanity of the participants, casting them and their ideas merely as side effects of the landscape. Diamond

The Enlightenment (The beginning of) a way of pursuing knowledge with a tradition of criticism and seeking good explanations instead of reliance on authority.

We shall always be faced with the problem of how to plan for an unknowable future.

Because pessimism needs to counter that argument in order to be at all persuasive, a recurring theme in pessimistic theories throughout history has been that an exceptionally dangerous moment is imminent.