With all due respect to Pratchett, that is pure codswallop. One datum, even though it may be relative true, is not a full understanding especially of something as complex as "people".

Responsibility, by its nature, tends to lift one up into larger spheres of knowing causation and willing participation.

One manifestation of this is that as an individual becomes more responsible, he starts taking other points of view into account. This ability to be pan-responsible is an extension of a lower step on the same ladder, being 'responsible for self alone'. You can see this growth in the maturation of young people (when they are healthy) for example.   You see it also when someone joins a new company as he or she acquires more awareness of the dynamics of the place.

Going down the spectrum from full responsibility to limited responsibility to completely madcap irresponsibility, the reverse happens -- one abandons taking responsibility for more than one's own view and defends it against others instead of being able to responsibly understand multiple vectors. Then one is left defending one's own responsibility against all others, and is on his way toward less and less responsibility.

The inability to communicate runs alongside the same spectrum -- and is often sympotmatic of it, in that one can't communicate into areas or about things for which he has abandoned all responsibility.

A