Four Approaches to Supposition

Suppositions can be introduced in either the indicative or subjunctive mood. There are also two types of judgments that may initiated by suppositions sort: qualitative (binary) and quantitative (numerical) ones. The former about whether a given proposition is acceptable latter how it is. We systematically explicate relationships between canonical representatives each four available theories. For accounts, our representative theories supposition based on belief change operations AGM revision KM update respectively; for ones, we consider those conditionalization imaging. This choice motivated familiar approach understanding as ‘provisional revision’ wherein one temporarily treats true forms making appropriate changes to their other opinions. To compare numerical recommended with binary ones appeal suitably adapted version Lockean thesis. Ultimately, establish number new results interpret vindicating often-repeated claim probabilistic revision, while imaging update.