All significant methodologies of the XX century accept conventionalistic philosophy of science. The main question for such methodologies is: are there universal criteria, allowing to choose these conventions, which are the best from the cognitive point of view? There are four classical answers to this problem: anarchism, sociologism, elitism and demarcationism. In the article the main dillemas of demarcationist program are considered.

Ludwik Fleck says that a thought-collective develops a thought-style which shapes the ways of perceiving the world and thinking of the world by its members. So how could it happen that at the end of 1900 Max Planck, whose thinking was determined by classical mechanics, managed to think that energy is quantized - the idea that contradicted the principles of Newton's mechanics? My answer is that Planck did not intend to think it.

The historical development of scientific knowledge is examined in the context of research, and not, as tradition tells, in the context of justification. It is a story about experimental researches and theoretical investigations conducted in the years 1820-1902, which finally led to the discovery of electron, accompanied by methodological comments. Main results of the analysis are that knowledge is scientific if it has a systemic character, and experimental studies are scientific if they are systematic. „Systemic” means that studied objects or (...) processes are assumed (a) to obey to the same laws, (b) if we know nothing about that the change of experimental situation can influence the given theoretical property of an object or process, than this property, determined in other successful applications of an accepted theory (i.e. the set of laws), should be attributed to objects or processes in new applications of the same theory. „Systematic” means that the same objects or processes are examined experimentally in a number of different, but interrelated, situations (so many as time, money and available laboratory instruments allow). I also try to show that in the historical growth of scientific knowledge hypotheses, understood as „free creations of the imagination”, do not play almost any role. Almost all theoretical discoveries are products of inferences that can be logically reconstructed and whose premises are (1) known and accepted laws of nature, (2) what is known about the studied objects on the basis of approved applications of these laws, (3) new experimental results. The moral of this is that theoretical discoveries appear if and only if the system of scientific knowledge is mature enough: it is impossible to draw conclusions, if you lack the necessary premises. A scientist cannot, by letting her imagination to run wild, to be ahead of her time, and if she tries to do that, she usually goes beyond the boundaries of science. (shrink)

If our thinking is socially conditioned, then how, at the end of 1900, did Max Planck, whose thinking was shaped by classical mechanics, manage to think that energy is quantized? After all, the idea was incommensurable with the principles of Newton’s mechanics. My thesis is that Planck did not intend to think about it. Trying to reconcile the time reversibility of the laws of mechanics with the time irreversibility of the laws of classical thermodynamics, he was constantly thinking according to (...) rules inherited from others. Trying to find a theoretical explanation of the formula describing the distribution of the energy of black-body radiation — arrived at by fitting theoretical parameters to new experimental data — he in “an act of despair” applied Boltzmann’s statistical concept of entropy. Then he noticed — on a sheet of paper — that classical and statistical formulas are identical if and only if the energy of resonators was a multiple of _hν_. What cannot appear in the human mind — as the mind is socially conditioned — can appear on paper. This gives a clear example of how computations in a “world on paper” can create new concepts. (shrink)

Is there a logic of scientific discovery? Are there logical relations between the knowledge scientists posses as they start their investigations and new hypotheses and theories they formulate? Can such relations be retrospectively reconstructed? Most philosophers of science in 20 th century claimed that processes of inventing new hypotheses or theories are not governed by any rules of logic. They claimed that new hypotheses are products of “leaps of imagination” that cannot be logically analyzed.

I agree with many of Adam Grobler’s theses, but several others raised my objection. (1) A.G. does not want to call scientific claims true. It is not so: very much of what scientists say about the world is true (in the classic sense), and scientists know it is. (2) A.G. leads us astray when he writes that the acceptance or rejection of hypotheses is determined, at least sometimes, by expert votes. It is not so: further research is the decisive factor (...) in accepting or rejecting hypotheses in science. (3) While A.G. is aware of some social determinants of knowledge, he ultimately states: “individuals are the subjects of scientific knowledge.” Contrary to this, I argue that one can only be a scientist as a member of a scientific thought collective. (4) A.G. believes that scientific knowledge is based on presuppositions, accepted unconsciously, that give meaning to statements made openly. After Wittgenstein, I repeat: “After all, nothing is concealed.”. (shrink)

If our thinking is socially conditioned, then how, at the end of 1900, did Max Planck, whose thinking was shaped by classical mechanics, manage to think that energy is quantized? After all, the idea was incommensurable with the principles of Newton’s mechanics. My thesis is that Planck did not intend to think about it. Trying to reconcile the time reversibility of the laws of mechanics with the time irreversibility of the laws of classical thermodynamics, he was constantly thinking according to (...) rules inherited from others. Trying to find a theoretical explanation of the formula describing the distribution of the energy of black-body radiation — arrived at by fitting theoretical parameters to new experimental data — he in “an act of despair” applied Boltzmann’s statistical concept of entropy. Then he noticed — on a sheet of paper — that classical and statistical formulas are identical if and only if the energy of resonators was a multiple of hν. What cannot appear in the human mind — as the mind is socially conditioned — can appear on paper. This gives a clear example of how computations in a “world on paper” can create new concepts. (shrink)