Oi, DDV
vou reproduzir aqui as críticas ao falseacionismo que contam no livro "Understanding Philosophy of Science" (2002), de James Ladyman:
Problems with falsificationism
There are several problems with Popper’s account of falsificationism. Some of these are specific to the details of the theory Popper first elaborated and so may be avoided by a more careful formulation or by revising some of the details. However, some are quite general and challenge the fundamental idea that it is possible to give an account of the scientific method without endorsing any kind of inductive inference. Below, some of the main criticisms of falsificationism are briefly explained.
(1) Some legitimate parts of science seem not to be falsifiable
(a) Probabilistic statements
Science often seems to issue statements about the probability of some occurrence. For example, modern physics tells us that the half life of uranium 235 is 710,000,000 years, which means that the probability of one atom of uranium decaying in 710,000,000 years is one-half or that it is highly probable that if one starts with 1 kg of uranium then in 710,000,000 years 500 g of it will have decayed. However, such statements cannot be falsified because an experiment may produce an improbable outcome and that is consistent with the original statement – improbable things are bound to happen sometimes. Any statement about the probability of a single event is not falsifiable, so, for example, the probability that a particular coin toss will land heads is 1/2, but we cannot falsify that hypothesis by tossing the coin because the fact that the probability is 1/2 is consistent with the coin landing heads or tails on that occasion. This problem does not arise for probabilities that are defined over large populations; hence, the statement that the probability that a particular coin will land heads 50 per cent of the time during a million tosses would be considered refuted if the coin landed tails 90 per cent of the time. I won’t say any more about probabilistic statements and theories except to point out that probability is a bit of a philosophical minefield for anyone, and that Popper did develop a detailed theory of probability whose merits we cannot assess here.
(b) Existential statements
Although Popper is right that a universal generalisation can be falsified by just one negative instance, many statements in science are not of this form. For example, scientific theories assert the existence of things like black holes, atoms, viruses, DNA and so on. Statements that assert the existence of something cannot be falsified by one’s failure to find them. Of course, if a theory asserts the existence of something that we repeatedly fail to find in various circumstances then one has inductive grounds for thinking it won’t be found in the future; however, falsificationism is supposed to allow us to do without inductive grounds for beliefs completely. This raises the question of the relationship between falsificationism and scientific realism. Popper is clear that belief in unobservable entities has often been an important influence on the ideas of scientists and has helped them generate highly falsifiable theories, such as the atomic theory of the elements that are central within physical science. However, his views on induction imply that one can never have positive grounds for believing in theoretical entities no matter how empirically successful the theories that posit them are. This contradicts the idea many people have that we have good reasons to believe that the entities to which our best current scientific theories seem to refer do in fact exist. We shall return to this issue later.
(c) Unfalsifiable scientific principles
It is arguable that some unfalsifiable principles may nonetheless be rightly considered part of scientific knowledge. So, for example, the status of the principle of conservation of energy, which states that energy can take different forms but cannot be created or destroyed, is such that it is inconceivable to most scientists that an experiment could falsify it; rather, an apparent violation of the principle would be interpreted as revealing that something is wrong with the rest of science and it is likely that a new source, sink or form of energy would be posited. It has also been argued that the second law of thermodynamics, which states that the entropy of any closed system always increases, is of such generality that it is beyond falsification.
(d) Hypothesis of natural selection
At one time, Popper was critical of the theory of evolution because he thought the hypothesis that the fittest species survive was tautological, that is to say true by definition, and therefore not falsifiable, yet evolutionary theory is widely thought to be a prime example of a good scientific theory. Most philosophers of biology would argue that the real content of evolutionary theory lies not in the phrase ‘the fittest survive’, but in the idea of organisms passing on characteristics, subject to mutation and variation, which either increase or decrease the chances of their offspring surviving long enough to reproduce themselves, and so pass on those characteristics. This is supposed to account for the existence of the great diversity of species and their adaptation to the environment, and also to the similarities of form and structure that exist between them. This theory may be indirectly falsifiable but the status of evolutionary explanations is too large a subject for us to enter into here.