The Lenore Thomson Exegesis Wiki
This might be what Lenore Thomson means by extraversion and introversion (as attitudes that people can take, not as personality types).
From an extraverted perspective, you see everything that someone does as an attempt to negotiate with others.
From an introverted perspective, negotiation has nothing to do with it. What is good is good, and that's why you do it.
So, for example, extraverts (people for whom an extraverted perspective is their "home base") typically interact by putting something on the table for others to react to, whether they like it or not.
Introverts (people for whom an introverted perspective is their "home base") typically interact by first asking permission to enter another person's space. You view each person as trying to understand and practice the good in his own way, and this process is not something to interfere with lightly.
From an extraverted perspective, one sees truth as a matter of agreement: by the rules of the social game, will people agree that a certain proposition is true? If no one will be convinced of a proposition, why bother saying it?
From an introverted perspective, one sees truth as a relation between your mind and the subject matter. Facts are not open to negotiation. Neither are ethical principles, causal laws, or anything else that the mind judges.
...more examples, anyone?...
It seems that ENTJs are often solitary, and take great pride in judging true or false, or better or worse, oblivious to other people's opinions. Perhaps this is their introverted side, but this seems part and parcel of their extraverted persona.
Possible explanation: These ENTJs are usually quick to jump to a false conclusion, after which they demand that someone else debate them out of it before they change their mind. However, if someone can "win" in fair debate against their proposition, they will immediately concede and change sides. Note that "fair" debate is an entirely social distinction, having nothing to do with the subject matter, though it might not seem this way to the participants.
See also: Negotiation Basics.