Testing for Acceptable Premises Within Systems of Belief

Many informal logic texts inform their readers to test premise acceptability in order to determine whether or not support or justification for a conclusion in an argument is cogent or warranted (for example Govier, 1985; MacKinnon, 1985). In some logic texts, premise acceptability is the first test which precedes and takes logical priority over tests of premise relevance and an adequate set of acceptably relevant premises to establish sufficient evidential grounds for a cogent argument. So, for example, Govier (1985) argues for a priority ranking of the cogency test that she calls the A acceptance, R relevance, and finally in priority order the G or grounds test for argument cogency. One of the standard tests for premise acceptability is whether a premise satisfies the common knowledge condition. However, this test is considered potentially problematic because it is believed that common knowledge varies by context and situation. Some theorists, such as Snell in The discovery of the mind (1953) and Jaynes in the Origin of Consciousness and the Bicameral Mind (1976), argue for a psychological or in the latter case a psychophysical origin for historical variations in the common sense belief set. Common beliefs change over time, change by audience, and change due to varying knowledge conditions, as argued by Thomas Kuhn, in the Structure of Scientific Revolutions (1962), his ironic contribution to the Encyclopedia of the Unified Sciences. So, according to these views, there is little “common” about common knowledge.