Online research in philosophy

The expansion or revision of false theories by true evidence does not always increase their verisimilitude. After a comparison of different notions of verisimilitude the relation between verisimilitude and belief expansion or revision is investigated within the framework of the relevant element account. We are able to find certain interesting conditions under which both the expansion and the revision of theories by true evidence is guaranteed to increase their verisimilitude.

Karl Popper introduced the idea of verisimilitude to explicate the intuitive idea that a theory T2, even though it is strictly speaking false, may be closer to the truth than a competitor T1. However, as is now well known, the results of Pavel Tichý, John Harris and David Miller establish that on Popper’s qualitative theory of verisimilitude, a theory T2 could be closer to the truth than another theory T1 only if T2 contains no false sentences. This result has been taken universally to show the inadequacy of Popper’s original account of verisimilitude, since the Miller-Tichý-Harris Theorem conflicts with the very basic intuition which first led Popper to formulate his theory.In this paper I shall first review the Miller-Tichý-Harris Theorem and examine a number of attempts to salvage the concept of verisimilitude. It will be argued that none of these attempts is successful. Finally an alternative, simple and intuitively satisfactory account of verisimilitude will be offered. This account will be along the lines first suggested by Popper, but it is not subject to any known limitation theorem. Further, the account is capable of giving verisimilitude orderings between not only scientific theories, but philosophical theories as well. This will be achieved without the use of the excessive formalism which dominates the contemporary verisimilitude research programs.

The inductive argument from the falsity of most past scientific theories (more than 100 years old) to the falsity of most present ones is defensible, I argue, if it is modified to account for the degrees of theoreticity or observationality in such theories, and the extent to which they are hedged. The case of descriptive astronomy is examined to show that most of the true theories of the 1890s were high in observationality and/or significantly hedged. The false theories of that period, however, were not even approximately true. Apparently, scientists are more interested in supplanting theories with improved observations than in producing true theories.

David Miller has demonstrated to the satisfaction of a variety of philosophers that the accuracy of false quantitative theories is language dependent (cf. Miller 1975). This demonstration renders the accuracy-based mode of comparison for such theories obsolete. The purpose of this essay is to supply an alternate basis for theory comparison which in this paper is deemed the knowledge-based mode of quantitative theory comparison. It is argued that the status of a quantitative theory as knowledge depends primarily on the soundness of the measurement procedure which produced the theory; such soundness is invariant, on my view, under Milleresque translations. This point is the basis for the linguistic invariance of knowledgelikeness. When the aim of science is not construed simply in terms of the truthlikeness or accuracy of theories, but in terms of the knowledge such theories embody, Miller's language dependence problem is overcome. One result of this analysis is that the possibility of objective scientific progress is restored, a possibility that Miller's analysis has prima facie defeated.

This paper analyses and criticizes S. Kripke's celebrated argument against materialist identity?theories. While criticisms of Kripke in the literature attack one or more of his premisses, an attempt is made here to show that Kripke's conclusion is unjustified even if his premisses are accepted. Kripke's premisses have sufficient independent plausibility to make this strategy interesting. Having stated Kripke's argument, it is pointed out that Kripke must assume that the contents of the Cartesian intuitions are clear and of a kind suited for the type of explanation he favours, while his own result concerning contents in epistemic contexts is precisely that this might not be so when objects or events we thought distinct happen to be identical. The point is that only by assuming that the identity?theory is false, can Kripke maintain that the Cartesian intuitions express contents which can be explained in his favoured way. But such an assumption is clearly illegitimate when the aim is to establish that the identity?theory is false. Kripke cannot conclude that the identity?theory is false because no explanation of epistemic possibilities is produced, since by his own standards no such explanation can be produced if the identity?theory is true.

Incommensurability of scientific theories, as conceived by Thomas Kuhnand Paul Feyerabend, is thought to be a major or even insurmountable obstacletothe empirical comparison of these theories. I examine this problem in light ofaconcrete case from the history of experimental biology, namely the oxidativephosphorylation controversy in biochemistry (ca. 1961-1977). After a briefhistorical exposition, I show that the two main competing theories which werethe subject of the ox-phos controversy instantiate some of the characteristicfeatures of incommensurable theories, namely translation failure,non-corresponding predictions, and different claims about what kinds ofentitiesexist in the world. By examining how the controversy was eventually resolved, Ithen show that at least this pair of incommensurable theories couldneverthelessbe empirically compared.

ACCORDING TO POPPER, SCIENTIFIC THEORIES ARE TO BE ACCEPTED IN SO FAR AS THEY ARE FALSIFIABLE AND IN SO FAR AS THEY HAVE BEEN CORROBORATED. THE CONCEPTS OF FALSIFIABILITY AND CORROBORATION ARE SUBMITTED TO DETAILED ANALYSIS. THE POINT OF ACCEPTING THEORIES, ACCORDING TO POPPER, IS TO OBTAIN THEORIES OF HIGH VERISIMILITUDE. HOWEVER THE BEST WE CAN DO IS TO OBTAIN THEORIES OF HIGH PROBABLE VERISIMILITUDE. POPPER’S CRITERIA FOR ACCEPTING THEORIES WILL ONLY LEAD TO THEORIES OF HIGH PROBABLE VERISIMILITUDE ON NON-POPPERIAN ASSUMPTIONS ABOUT INDUCTION.

In the paper ordering relations for comparison of verisimilitude of theories are introduced and discussed. The relations refer to semantic analysis of the results of theories, in particular to analysis of concepts the theories deal with.

Science progresses if we succeed in rendering the objects of scientific inquiry more comprehensively or more precisely. Popper tries to formalize this venerable idea. According to him the most comprehensive and most precise description of the world is given by the set T of all true statements. A hypothesis comes the closer to T, or has the more verisimilitude, the more true consequences and the fewer false consequences it implies. Popper proposes to order hypotheses by the inclusion relations between the sets of their true and of their false consequences ("truth contents" and "falsity contents"). A partial ordering would permit one to decide whether the substitution of theory t 1 by t 2 represents scientific progress. But because of the logical relations between the elements of the sets of logical consequences, or contents, false hypotheses cannot be compared. As our theories usually turn out to be false sooner or later, they can seldom be compared as to their verisimilitude and when they can, the result depends only on which theory implies the other and on their truth-values. Popper even tries to define a measure of verisimilitude on the partial ordering. It has to fail for the same reason. In addition he tries to relativize the concept of a content and fails. What is more, any attempt at defining a measure of better or worse correspondence to the whole truth must fail, as there is no justification for saying that any true primitive sentence asserts as much about reality as some other primitive sentence, or more.

Popper’s original definition of verisimilitude in terms of comparisons of truth content and falsity content has known counter-examples. More complicated approaches have met with mixed success. This paper uses a new account of logical content to develop a definition of verisimilitude that is close to Popper’s original account. It is claimed that Popper’s mistake was to couch his account of truth and falsity content in terms of true and false consequences. Comparison to a similar approach by Schurz and Wiengartner show certain advantages of this new approach.