Feeling, according to Jung, is also a rational function. This is not to be confused with emotion, or affect. It is also not to be confused with Intuition which is often self-consciously described as a feeling, "I feel that he won't understand." Feeling is the rational function of evaluating the world in terms of "value".
A classic example for me is when I was debating with a Feeling type (I'm a Thinking type) and we were talking about whether illegal immigrants should get medical care. I was taking the side of the law and that people whose presence in this country isn't legal don't have any rights so they don't have the right to expect treatment. The other person was considering how a person in need of medical treatment needs help and shouldn't be discriminated on on the basis of their legal status because that is not as important as that they get the medical treatment that they need.
Although both arguments were rational, mine was based on the definition of legal status and rights and the other was based on human need and values. The distinction wasn't perfect but I realized then that both of us were being rational but talking at cross purposes because I was basing my rational argument on the logic of how words and their meanings were defined and the other person was basing their argument on what is important and of value when responding to the needs of another human being.
Evaluating the world according to values and importance is a rational process that involves...
- Defining one's values
- Considering all the relevant aspects of the situation
- Reasoning logically using "valuations" rather than "word definitions"
- Stating a conclusion with supporting statements logically related to that conclusion
Once you see this distinction and once you learn that modern neurologists have found distinct areas of the brain that deal with "logic" and "evaluation" (see Damasio's
Descartes Error) you can then begin to realize that many of the arguments people have that go in circles are precisely due to a difference in their natural personal typology (thinking vs feeling rational types).
Of course even within a type the premises may be different but then one should be able to get down to a shared but opposite assumption. Across the types no such specific disagreement can be reached. It is two separate (though also overlapping) realms of rational thought.