Online research in philosophy

This paper is a critique of Contessa’s (in the same issue). First, I show that Popper in The Logic of Scientific Discovery argues against the view that the logical probability of a hypothesis is identical to its degree of confirmation (or corroboration), rather than against Bayesianism. Second, I explain that his argument to this effect does not depend on the assumption that ‘the universe is infinite’. Third, and finally, I refine Popper’s case by developing an argument which requires only that some universal laws have a logical probability of zero relative to any finite evidence, and providing an example concerning Newtonian mechanics.

This book presents a comprehensive and systematic account of the various philosophical theories of probability and explains how they are related. It covers the classical, logical, subjective, frequency, and propensity views of probability. Donald Gillies even provides a new theory of probability -the intersubjective-a development of the subjective theory. He argues for a pluralist view, where there can be more than one valid interpretation of probabiltiy, each appropriate in a different context. The relation of the various interpretations to the Bayesian controversy, which has become central in both statistics and philosophy of science, is explained as well.

We examine three critical aspects of Popper’s formulation of the ‘ Logic of Scientific Discovery ’—evidence, content and degree of corroboration—and place these concepts in the context of the Tree of Life (ToL) problem with particular reference to molecular systematics. Content, in the sense discussed by Popper, refers to the breadth and scope of existence that a hypothesis purports to explain. Content, in conjunction with the amount of available and relevant evidence, determines the testability, or potential degree of corroboration, of a statement; content distinguishes scientific hypotheses from metaphysical assertions. Degree of corroboration refers to the relative and tentative confidence assigned to one hypothesis over another, based upon the performance of each under critical tests. Here we suggest that systematists attempt to maximize content and evidence to increase the potential degree of corroboration in all phylogenetic endeavors. Discussion of this “total evidence” approach leads to several interesting conclusions about generating ToL hypotheses.

The probabilistic corroboration of two or more hypotheses or series of observations may be performed additively or multiplicatively . For additive corroboration (e.g. by Laplace's rule of succession), stochastic independence is needed. Inferences, based on overwhelming numbers of observations without unexplained counterinstances permit hyperinduction , whereby extremely high probabilities, bordering on certainty for all practical purposes may be achieved. For multiplicative corroboration, the error probabilities (1 - Pr) of two (or more) hypotheses are multiplied. The probabilities, obtained by reconverting the product, are valid for both of the hypotheses and indicate the gain by corroboration.. This method is mathematically correct, no probabilities > 1 can result (as in some conventional methods) and high probabilities with fewer observations may be obtained, however, semantical independence is a prerequisite. The combined method consists of (1) the additive computation of the error probabilities (1 - Pr) of two or more single hypotheses, whereby arbitrariness is avoided or at least reduced and (2) the multiplicative procedure . The high reliability of Empirical Counterfactual Statements is explained by the possibility of multiplicative corroboration of "all-no" statements due to their strict semantical independence.

1. Sir Karl Popper has offered two different theories of scientific progress, his theory of conjectures and refutations and corroboration, as well as his theory of verisimilitude increase. The former was attacked by some old-fashioned inductivists, yet is triumphant; the latter has been refuted by Tichy and by Miller to Popper’s own satisfaction. Oddly, however, the theory of verisimilitude was developed because of some deficiency in the theory of corroboration, and though in its present precise formulation it was refuted, Popper still holds it in general terms, and I think he still hopes to find a better precise formulation of it. My aims in the present note are to pin-point the deficiency of Popper’s theory of corroboration and to use this for a precise formulation of verisimilitude increase acceptable to him. For my part, however, I see the situation in a different way, as will be indicated at the end of this note.

Popper’s Critical Rationalism presents Popper’s views on science, knowledge, and inquiry, and examines the significance and tenability of these in light of recent developments in philosophy of science, philosophy of probability, and epistemology. It develops a fresh and novel philosophical position on science, which employs key insights from Popper while rejecting other elements of his philosophy.

Central theses include:

Crucial questions about scientific method arise at the level of the group, rather than that of the individual.

Although criticism is vital for science, dogmatism is important too.

Belief in scientific theories is permissible even in the absence of evidence in their favour.

The aim of science is to eliminate false theories.

Critical rationalism can be understood as a form of virtue epistemology

Contents:

Ch.1 Comprehensive rationalism, critical rationalism, and pancritical rationalism -- Ch.2 Induction and corroboration -- Ch.3 Corroboration and the interpretation of probability -- Ch.4 Corroboration, tests, and predictivism -- Ch.5 Corroboration and Duhem's thesis -- Ch.6 The roles of criticism and dogmatism in science: a group level view -- Ch.7 The aim of science and its evolution -- Ch.8 Thoughts and findings.

This paper presents a new 'discontinuous' view of Popper's theory of corroboration, where theories cease to have corroboration values when new severe tests are devised which have not yet been performed, on the basis of a passage from The Logic of Scientific Discovery . Through subsequent analysis and discussion, a novel problem for Popper's account of corroboration, which holds also for the standard ('continuous') view, emerges. This is the problem of the Big Test: that the severest test of any hypothesis is actually to perform all possible tests (when 'possible' is suitably interpreted). But this means that Popper's demand for 'the severest tests' amounts simply to a demand for 'all possible tests'. The paper closes by considering how this bears on accommodation vs. prediction, with respect to corroboration.

This paper argues that Duhem’s thesis does not decisively refute a corroboration-based account of scientific methodology (or ‘falsificationism’), but instead that auxiliary hypotheses are themselves subject to measurements of corroboration which can be used to inform practice. It argues that a corroboration-based account is equal to the popular Bayesian alternative, which has received much more recent attention, in this respect.

This paper shows that Popper’s measure of corroboration is inapplicable if, as Popper also argued, the logical probability of synthetic universal statements is zero relative to any evidence that we might possess. It goes on to show that Popper’s definition of degree of testability, in terms of degree of logical content, suffers from a similar problem.

This paper introduces what is called the intersubjective interpretation of the probability calculus. Intersubjective probabilities are related to subjective probabilities, and the paper begins with a particular formulation of the familiar Dutch Book argument. This argument is then extended, in Section 3, to social groups, and this enables the concept of intersubjective probability to be introduced in Section 4. It is then argued that the intersubjective interpretation is the appropriate one for the probabilities which appear in confirmation theory whether of a Bayesian or a Popperian variety. The final section of the paper states and tries to answer an objection due to Putnam.