Degrees of Certainty and Sensitive Knowledge

Abstract


 
 
 In recent work, I have argued that what Locke calls ‘sensitive knowledge’ is not really knowledge, according to his own definition. Knowledge, as Locke defines it, is the perception of an agreement or disagreement between two ideas (E, IV.ii.15: 538). However, on Locke’s theory, sensitive knowledge, which is supposed to be knowledge via sensation of the existence of material objects outside the mind, is really better understood as a kind of assurance (i.e.,1 assent or belief based on the highest degree of probability). On this reconstruction, assurance, as Locke describes it, is a kind of doxastic state that is incompatible with reasonable doubt, but compatible with extreme hyperbolic skeptical doubt. But assurance, as Locke avers, falls short of knowledge, for it is a kind of non-factive presumption, rather than a kind of factive perception, of ideational agreement or disagreement. Locke, I claim, calls assurance of the existence of external material objects ‘sensitive knowledge’ because assurance and knowledge are indistinguishable in their practical effects: assurance, no less than knowledge, leads to action without hesitation, given the absence of reasonable doubt that there is an external world to act in. My conception of Lockean sensitive knowledge as a kind of assurance that falls short of genuine knowledge has recently been criticized in the pages of this journal by David Soles (2014). My aim here is to answer Soles’s criticisms.