Knowledge – Explicit , implicit and tacit : Philosophical aspects

Explicit knowledge is knowledge that the knower can make explicit by means of a verbal statement; implicit knowledge is knowledge that is not explicit. Chomskyan tacit knowledge of rules can be understood as requiring a particular structure in the content-involving explanations of transitions between internal representations. States of tacit knowledge are different from beliefs and states of explicit knowledge in that their content is at least partly nonconceptual. Several applications of the notion of tacit knowledge in philosophical theory are reviewed. Chomsky’s notion of tacit knowledge of the rules of a generative grammar provided the theoretical background for research on artificial grammar learning (AGL). Results and disputes in AGL research are reviewed, with particular reference to requirements on testing for conscious versus unconscious knowledge. No test is guaranteed to meet the requirements but tests can be validated if they are used in the context of psychological theories about qualitative differences between conscious and unconscious processes. Explicit knowledge is knowledge that the knower can make explicit by means of a verbal statement: ‘Someone has explicit knowledge of something if a statement of it can be elicited from him by suitable enquiry or prompting’ (Dummett 1991). Implicit knowledge can then be defined simply as knowledge that is not explicit. On this construal, implicit knowledge corresponds roughly to what Polanyi (1967) calls ‘tacit knowing’: ‘we can know more than we can tell’. Tacit knowing in Polanyi’s sense encompasses a variety of phenomena, such as the ability to recognize something (e.g. a person’s face) even though one cannot describe in context-independent terms (e.g. without saying, ‘I know that Bob looks like this’) how one recognizes it. Polanyi’s tacit knowing also includes the holistic diagnostic skills that an experienced and humane psychologist or psychiatrist brings to a clinical encounter. Diagnostic judgment depends on ‘content-dependent practical knowledge’ (Thornton 2013). While explicit knowledge can be expressed and communicated linguistically, Polanyi’s tacit knowing cannot be captured in language without reliance on contextdependent or demonstrative elements (e.g. I know that to tie my shoelaces I move my fingers thus (in this way)’. But tacit knowing can still be communicated and shared. The mechanism of transmission is not telling and understanding, but rather performance and imitation (learning by example). The notion of socially and culturally shared knowledge in the service of solving theoretical and practical problems (perhaps in the form of shared * I am grateful to Zoltan Dienes, David Lobina and Crysostomos Mantzavinos for their comments and advice.