Tag: induction

Observe!

The belief that science proceeds from observation to theory is still so widely and so firmly held that my denial of it is often met with incredulity. I have even been suspected of being insincere – of denying what nobody in his senses can doubt.

But in fact the belief that we can start with pure observations alone, without anything in the nature of a theory, is absurd; as may be illustrated by the story of the man who dedicated his life to natural science, wrote down everything he could observe, and bequeathed his priceless collection of observations to the Royal Society to be used as inductive evi­dence. This story should show us that though beetles may profitably be collected, observations may not.

Twenty-five years ago I tried to bring home the same point to a group of physics students in Vienna by beginning a lec­ture with the following instructions: ‘Take pencil and paper; carefully observe, and write down what you have observed!’ They asked, of course, what I wanted them to observe. Clearly the instruction, ‘Observe!’ is absurd. (It is not even idio­matic, unless the object of the transitive verb can be taken as understood.) Observation is always selective. It needs a chosen object, a definite task, an interest, a point of view, a problem. And its description presupposes a descriptive lan­guage, with property words; it presupposes similarity and classification, which in its turn presupposes interests, points of view, and problems. [61]

Science: It works, bitches

Question: The question is about the nature of scientific evidence. You both said, and I think most people here would agree with you, that we’re justified in holding a belief if there is evidence for it or there are logical argumentes we can find that support it. But it seems like this in itself is a belief, which would require some form of evidence. If so, I’m won­dering what you think would count as evidence in favour of that and, if not, how do we justify choosing that heuristic without appealing to the same standard that we are trying to justify?

Dawkins: How do we justify, as it were, that science would give us the truth? It works. Planes fly, cares drive, computers compute.

Law: It’s an inductive argument.

Dawkins: If you base medicine on science, you cure people; if you base the design of planes on science, they fly; if you base the design of rockets on science, they reach the moon. It works … bitches. [1:10:30]

Kant’s improvement on Hume

Thus Kant’s reply to Hume came near to being right; for the distinction between an a priori valid expectation and one which is both genetically and logically prior to observation, but not a priori valid, is really somewhat subtle. But Kant proved too much. In trying to show how knowledge is possible, he proposed a theory which had the unavoidable consequence that our quest for knowledge must necessarily succeed, which is clearly mistaken. When Kant said, ‘Our intellect does not draw its laws from nature but imposes its laws upon nature’, he was right. But in thinking that these laws are necessarily true, or that we necessarily succeed in imposing them upon nature, he was wrong. Nature very often resists quite successfully, forcing us to discard our laws as refuted; but if we live we may try again. [63]

Shadows of Baconian induction (2)

The Large Hadron Collider is the most complicated scientific experiment ever built. But it’s still just an experiment like any other. At its heart, there is repeatable process, as with Newton’s prism. There are teams of people dedicated to making detailed measurements, as Cavendish did with his flammable air. And the same rigorous logical thought processes used by Bill Tutte are of course applied here too. These are simple principles, yet they hold great power. [51:15]

Newtonian induction

The common explanation for the appearance of the colours was that they were added by impurities in the prism to the pure white light. Newton thought that the colours were already present in the white sunlight. But what set Newton apart was that he devised and performed an experiment to test his hypothesis. …

Green light into the prism equals green light out. That implies that the colours themselves are pure. The prism is not subtracting or adding anything. That means that Newton’s hypothesis was shown to be correct. …

Newton was one of the first to interrogate Nature using the principles of what we now call the scientific method. In other words, he observed the world, came up with theories to explain what he saw, then tested them with experiments to see if he was right. The power of this approach is that it aims to remove preconceived ideas and, in doing so, deliver a more accurate description of the natural world.  [7:40]

Gathering evidence

[G]athering evidence and building arguments from what can be seen and reproduced is at the heart of a modern scientist’s work. [41]

Veiled induction: explanations based on evidence

Darwinian evolution is the most robust of scientific theories, but many people find it easier and more reassuring to believe that something so intricately constructed as life on Earth must have had a designer. It is hard for us to accept that erverything around us, from the beautry of the butterfly to the complexity of the human eye, could have evolved simply through chance and the pressure to survive. But the scientific evidence that evolution by natural selection has occurred is unassailable.

The scientific method, which is today practised in all corners of the globe, builds on explanations based on evidence, and when new evidence emerges that does not fit with the model, the explanation must change. That is how science moves on. [15]

The logic of scientific methodology

According to the view that will be put forward here, the method of critically testing theories, and selecting them ac­cording to the results of tests, always proceeds on the following lines. From a new idea, put up tentatively, and not yet justified in any way—an anticipation, a hypothesis, a theoretical system, or what you will—conclusions are drawn by means of logical deduction. These conclusions are then compared with one another and with other relevant state­ments, so as to find what logical relations (such as equivalence, derivability, compatiblity, or incompatibility) exist be­tween them.

We may if we like distinguish four different lines along which the testing of a theory could be carried out. First there is the logical comparison of the conclusions among themselves, by which the internal consistency of the system is tested. Secondly, there is the investigation of the logical form of the theory, with the object of determining whether it has the character of an empirical or scientific theory, or whether it is, for example, tautological. Thirdly, there is the comparison with other theories, chiefly with the aim of determining whether the theory would constitute a scientific advance should it survive our various tests. And finally, there is the testing of the theory by way of empirical applications of the conclusions which can be derived from it.

The purpose of this last kind of test is to find out how far the new consequences of the theory—whatever may be new in what it asserts—stand up to the demands of practice, whether raised by purely scientific experiments, or by practical technological applications. Here too the procedure of testing turns out to be deductive. With the help of other state­ments, previously accepted, certain singular statements—which we may call ‘predictions’—are deduced from the theory; especially predictions that are easily testable or applicable. From among these statements, those are selected which are not derivable from the current theory, and more especially those which the current theory contradicts. Next we seek a decision as regards these (and other) derived statements by comparing them with the results of practical applications and experiments. If this decision is positive, that is, if the singular conclusions turn out to be acceptable, or verified, then the theory has, for the time being, passed its test: we have found no reason to discard it. But if the decision is negative, or in other words, if the conclusions have been falsified, then their falsification also falsifies the theory from which they were logically deduced.

It should be noticed that a positive decision can only temporarily support the theory, for subsequent negative decisions may always overthrow it. So long as [the] theory withstands detailed and severe tests and is not superseded by another theory in the course of scientific progress, we may say that it has ‘proved its mettle’ or that it is ‘corroborated’ by past experience.

Nothing resembling inductive logic appears in the procedure here outlined. I never assume that we can argue from the truth of singular statements to the truth of theories. I never assume that by force of ‘verified’ conclusions, theories can be established as ‘true’, or even as merely ‘probable’. [9-10]

The evolution of problems

This consideration of the fact that theories or expectations are built into our very sense organs shows that the episte­mology of induction breaks down even before taking its first step. It cannot start from sense data or perceptions and build our theories upon them, since there are no such things a sense data or perceptions which are not built upon theories (or expectations—that is, the biological predecessors of linguistically formulated theories). Thus the ‘data’ are no basis of, no guarantee for, the theories. They are not more secure than any of our theories or ‘prejudices’ but, if anything, less so (assuming for argument’s sake that sense data exist and are not philosophers’ inventions). Sense organs incorporate the equivalent of primitive and uncritically accepted theories, which are less widely tested than scientific theories. …

Thus life proceeds, like scientific discovery, from old problems to the discovery of new and undreamt-of problems. And this process—that of invention and selection—contains in itself a rational theory of emergence. The steps of emergence which lead to a new level are in the first instance the new problems (P2) which are created by the error-elimination (EE) of a tentative theoretical solution (TT) of an old problem (P1). [146]

The thousand-fold experience of induction

I found that those of my friends who were admirers of Marx, Freud, and Adler, were impressed by a number of points common to these theories, and especially by their apparent explanatory power. These theories appeared to be able to explain practically everything that happened within the fields to which they referred. The study of any of them seemed to have the effect of an intellectual conversion or revelation, opening your eyes to a new truth hidden from those not yet initiated. Once your eyes were thus opened you saw confirming instances everywhere: the world was full of verifi­cations of the theory. Whatever happened always confirmed it. Thus its truth appeared manifest; and unbelievers were clearly people who did not want to see the manifest truth; who refuse to see it, either because it was against their class interest, or because of their repressions which were still ‘un-analyzed’ and crying out for treatment.

The most characteristic element in this situation seemed to me the incessant stream of confirmations, of observations which ‘verified’ the theories in question; and this point was constantly emphasize by their adherents. A Marxist could not open a newspaper without finding on every page confirming evidence for his interpretation of history; not only in the news, but also in its presentation—which revealed the class bias of the paper—and especially of course what the paper did not say. The Freudian analysts emphasized that their theories were constantly verified by their ‘clinical observa­tions’. As for Adler, I was much impressed by a personal experience. Once, in 1919, I reported to him a case which to me did not seem particularly Adlerian, but which he found no difficulty in analyzing in terms of his theory of inferiority feelings, although he had not even seen the child. Slightly shocked, I asked him how he could be so sure. ‘Because of my thousandfold experience’, he replied; whereupon I could not help saying: ‘And with this new case, I suppose, your experience has become thousand-and-one-fold.’ [45-6]