I'm reading the page at http://www.teamtechnology.co.uk/keirsey-analysis.html, where it quotes Keirsey saying,
"Myers' E-I scale is badly flawed because she inherited Jung's error of confusing extraversion with observation (S) and introversion with introspection (N). And so to make the E-I distinction useful at all, we must define the two concepts, not in terms of mental focus or interest, but in terms of social address or social attitude."
So for Keirsey, the E-I distinction defines a "social address or social attitude."
Then why does the author of that webpage say the following a few paragraphs later? -
But this criticism of Keirsey simply redefines his I-E distinction in terms of mental attitudes, whereas his is defined in terms of social address or social attitudes. Therefore, it stands as a straw-dog criticism of Keirsey's analysis of the ISTP temperament.Clearly, when Keirsey describes an ISTP he uses terms that are much more 'extraverted', and when he describes an INTP he uses terms that are much more 'introverted'. By comparison, Isabel Briggs-Myers description of ISTP is written in terms of the introverted Thinking dominant function... In fact, Isabel Briggs-Myers description is in some ways opposed to Keirsey's: whereas he describes them [the ISTP] as action-driven, she states that they are "great believers in economy of effort". Keirsey resolves this difference by stating that Isabel Briggs-Myers "inherited Jung's confusion between Sensing and Extraversion", but in this respect her writings are completely consistent, and she portrays ISTPs as introverts. Keirsey portrays ISTPs in an extravert fashion because his system of temperament is different to Jungian typology - and the use of the same system of letters to describe both is unfortunate because of the confusion it both causes, and hides.