Theory

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. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

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. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

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. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

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. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

Whenever a wide range of variant theories can account equally well for the phenomenon they are trying to explain, there is no reason to prefer one of them over the others, so advocating a particular one in preference to the others is irrational. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

The fundamental theories of modern physics explain the world in jarringly counter-intuitive ways. For example, most non-physicists consider it self-evident that when you hold your arm out horizontally you can feel the force of gravity pulling it downwards. But you cannot. The existence of a force of gravity is, astonishingly, denied by Einstein’s general theory of relativity, one of the two deepest theories of physics. This says that the only force on your arm in that situation is that which you yourself are exerting, upwards, to keep it constantly accelerating away from the straightest possible path in a curved region of spacetime — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

Shoddy explanations that yield correct predictions are two a penny, as UFO enthusiasts, conspiracy-theorists and pseudo-scientists of every variety should (but never do) bear in mind. — David Deutsch, The Fabric of Reality: The Science of Parallel Universes — and Its Implications

Since theories can contradict each other, but there are no contradictions in reality, every problem signals that our knowledge must be flawed or inadequate. — David Deutsch, The Beginning of Infinity: Explanations that Transform The World

But, in reality, scientific theories are not ‘derived’ from anything. We do not read them in nature, nor does nature write them into us. They are guesses – bold conjectures. Human minds create them by rearranging, combining, altering and adding to existing ideas with the intention of improving upon them. — David Deutsch, The Beginning of Infinity: Explanations that Transform The World

We do not begin with ‘white paper’ at birth, but with inborn expectations and intentions and an innate ability to improve upon them using thought and experience. Experience is indeed essential to science, but its role is different from that supposed by empiricism. It is not the source from which theories are derived. Its main use is to choose between theories that have already been guessed. That is what ‘learning from experience’ is. — David Deutsch, The Beginning of Infinity: Explanations that Transform The World

The quest for good explanations is, I believe, the basic regulating principle not only of science, but of the Enlightenment generally. It is the feature that distinguishes those approaches to knowledge from all others, and it implies all those other conditions for scientific progress I have discussed: It trivially implies that prediction alone is insufficient. Somewhat less trivially, it leads to the rejection of authority, because if we adopt a theory on authority, that means that we would also have accepted a range of different theories on authority. And hence it also implies the need for a tradition of criticism. — David Deutsch, The Beginning of Infinity: Explanations that Transform The World

So there is no resource-management strategy that can prevent disasters, just as there is no political system that provides only good leaders and good policies, nor a scientific method that provides only true theories. But there are ideas that reliably cause disasters, and one of them is, notoriously, the idea that the future can be scientifically planned. The only rational policy, in all three cases, is to judge institutions, plans and ways of life according to how good they are at correcting mistakes: removing bad policies and leaders, superseding bad explanations, and recovering from disasters. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

We do so by seeking good explanations – explanations that are hard to vary in the sense that changing the details would ruin the explanation. This, not experimental testing, was the decisive factor in the scientific revolution, and also in the unique, rapid, sustained progress in other fields that have participated in the Enlightenment. That was a rebellion against authority which, unlike most such rebellions, tried not to seek authoritative justifications for theories, but instead set up a tradition of criticism. — David Deutsch, The Beginning of Infinity: Explanations that Transform The World

To avoid misunderstanding, let me stress that experience provides problems only by bringing already-existing ideas into conflict. It does not, of course, provide theories. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

The second fundamental misconception in inductivism is that scientific theories predict that ‘the future will resemble the past’, and that ‘the unseen resembles the seen’ and so on. (Or that it ‘probably’ will.) But in reality the future is unlike the past, the unseen very different from the seen. Science often predicts – and brings about – phenomena spectacularly different from anything that has been experienced before. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

They can be understood only by being explained. Fortunately, our best theories embody deep explanations as well as accurate predictions. — David Deutsch, The Fabric of Reality: Towards a Theory of Everything

Scientific theories explain the objects and phenomena of our experience in terms of an underlying reality which we do not experience directly. But the ability of a theory to explain what we experience is not its most valuable attribute. Its most valuable attribute is that it explains the fabric of reality itself. — David Deutsch, The Fabric of Reality: Towards a Theory of Everything

We understand the fabric of reality only by understanding theories that explain it. And since they explain more than we are immediately aware of, we can understand more than we are immediately aware that we understand. — David Deutsch, The Fabric of Reality: Towards a Theory of Everything

Thus the issue of whether it is becoming harder or easier to understand everything that is understood depends on the overall balance between these two opposing effects of the growth of knowledge: the increasing breadth of our theories, and their increasing depth. Breadth makes it harder; depth makes it easier. One thesis of this book is that, slowly but surely, depth is winning. In other words, the proposition that I refused to believe as a child is indeed false, and practically the opposite is true. We are not heading away from a state in which one person could understand everything that is understood, but towards it. — David Deutsch, The Fabric of Reality: Towards a Theory of Everything

The real source of our theories is conjecture, and the real source of our knowledge is conjecture alternating with criticism. We create theories by rearranging, combining, altering and adding to existing ideas with the intention of improving upon them. The role of experiment and observation is to choose between existing theories, not to be the source of new ones. We interpret experiences through explanatory theories, but true explanations are not obvious. Fallibilism entails not looking to authorities but instead acknowledging that we may always be mistaken, and trying to correct errors. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

Fundamental or significant phenomenon: One that plays a necessary role in the explanation of many phenomena, or whose distinctive features require distinctive explanation in terms of fundamental theories. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

Parochialism: Mistaking appearance for reality, or local regularities for universal laws. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

Person: An entity that can create explanatory knowledge. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

One consequence of this tradition of criticism was the emergence of a methodological rule that a scientific theory must be testable (though this was not made explicit at first). That is to say, the theory must make predictions which, if the theory were false, could be contradicted by the outcome of some possible observation. Thus, although scientific theories are not derived from experience, they can be tested by experience – by observation or experiment. — David Deutsch, The Beginning of Infinity: Explanations that Transform The World

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. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World

For most of the history of our species, we had almost no success in creating such knowledge. Where does it come from? Empiricism said that we derive it from sensory experience. This is false. The real source of our theories is conjecture, and the real source of our knowledge is conjecture alternating with criticism. — David Deutsch, The Beginning of Infinity: Explanations That Transform the World