Chisholm, Roderick Milton

« Chisholm published three editions of his Theory of Knowledge .

In all three, he was a pure foundationalist for a priori knowing, claiming that any a priori knowledge was either intuitively certain or known to be deducible from what was intuitively certain ( A priori §3 ).

However, his account of empirical knowledge was a much more complicated story, containing a strong coherentist component.

While claiming that certain internal mental states were 'self -presenting' and thus not in need of any evidential support, Chisholm consistently required substantial coherence among one's internal beliefs before one was justified in believing any proposition which went beyond the internal. The foundational or anchoring self-presenting states and their corresponding beliefs consist of a variety of 'seemings' .

What one seems to believe, seems to intend, seems to hope for or fear and, most importantly, seems to perceive, are all self-presenting; that is, if one is in any of these states and believes that one is in the state, then that belief is certain.

Chisholm, following up a suggestion of his colleague Curt Ducasse, developed an adverbial theory of sensory experiencing.

Chisholm urged that when referring to internal experiencing, we replace talk of 'sense -data' with adverbial expressions such as 'being appeared to redly' .

In Chisholm's view, having the property of being appeared to redly was self-presenting and, thus, certain.

The main advantage of this artificial way of speaking was the avoidance of ontological and epistemic puzzles about sense data.

While 'being appeared to redly' is somewhat comprehensible, the approach requires similar adverbs for all the other possible modes of sensing and suffers some implausibility because of their absence from ordinary language ( Mental states, adverbial theory of ). A fundamental characteristic of Chisholm's approach was to employ a fertile primitive term together with simple logical relationships to define other more complex concepts.

For example, in the 3rd edition of Theory of Knowledge (1989b) the central foundational category of the 'certain' was defined in terms of the primitive comparative term 'more justified than' as follows: p is certain for S =Df For every q, believing p is more justified for S than withholding q, and believing p is at least as justified for S as is believing q. Definitions such as these occur throughout his work and it would not be inappropriate to label his approach 'Definitionalism' .

Because of their clarity and simplicity, Chisholm's definitions generated numerous responses, mostly proposed counter-instances.

Chisholm welcomed every example and never tired of modifying or 'chisholming away at' his definitions. Chisholm handled epistemological scepticism by assuming that we have particular justified beliefs and the ability to examine them critically and thereby to discover principles of justification.

These principles enabled Chisholm to construct a fifteen-category epistemic hierarchy, ranging from the certainly false to the certainly true.

Each of the categories is defined in terms of the primitive 'more justified than' .

Chisholm glosses this primitive in terms of an. »