ISTJs act appropriately within the given social constraints.I think my Dad is a T (ISTJ I think) he is inappropriate and offensive all the time but when he should be offensive (when being pestered by telemarketers etc.) all of a sudden he is Mr Politeness, what's the deal with that?
You're a bit vague on what situations your dad is inappropriate/offensive in, but in regards to telemarketers, the social situation is, well, social, with strangers, and hence he takes on an appropriate stance and a more formal one... if he's ISTJ.
T's naturally detach from feelings when they evaluate a situation in order to pass a judgment. They see feelings as "white noise." More mature T's will use them as signals to describe, well, personal values, and if they believe the situation calls for those personal values to be included in the decision, then they will... but the decision is generally a conscious one and chosen. (For example, getting mad at something someone did is evaluated, the anger is seen as a logical consequence of being violated, and so the T might rationally decide to not invest any more in a particular relationship because they were violated... but it's a rational thinking process being used to reach the conclusion.)Originally Posted by BBNB
F's are far more likely to include feelings in a decision, to whatever degree those personal feelings align with personal values and the values are far more instinctive instead of rationalized.