Evidential support and undermining: Revision of Håkan Törnebohm's theory of confirmation

Summary

In 1975, ‘An Essay on Knowledge Formation’ by H. Törnebohm was published in this Journal. Its content in revised form was included in a work in Swedish of 1983 on knowledge development.

HT defines his confirmation criterion in terms of a measure oftruth degree T, which is based on a measure ofmatching M, which is also used as a measure of the degree to which propositionp (an hypothesis) is supported or undermined by another propositionq (the evidence forp),M is defined in terms of a measure of thecontent C.

Here it is argued that HT works with two measuresC: (1) a firstC, which is defined only for consistent propositions and which really is a measure of content; (2) a finalC, which is an inverted measure of probability rather than a measure of content. As an extension of HT's firstC, a new content measure, defined also for inconsistent propositions, is constructed.

HT's measureM, which is based on his finalC, is replaced by one measure ofsupport and one ofundermining. Both are based on the new content measure.