Catholics should accept this basic truth.
Subjectivism and relativism destroy rational discourse. So many people fall into the great fallacies because they lack objectivity. I have written in the perfection series that objectivity is a sign of the saint. The person who can stand back and be objective about themselves is "putting on the mind of Christ".
Those who refuse to be objective cannot be holy. Virtues are also objective. These gifts, given to us at baptism, are not feelings, nor based on feelings.
If I am patient today with someone who is difficult, the decision to be patient is not based on how I feel but how I act and how I think-which in this case would be in a position of humility.
Irrationality is so subjective that it leads one to insanity. Insanity has many meanings. Take a look at these definitions. This is why when one sins over and over and over, one can become insane. Insanity, not always, as it can be medical, can be extreme folly or unreasonableness. This is another definition of sin.
http://www.merriam-webster.com/dictionary/insanity
1
: a deranged state of the mind usually occurring as a specific disorder (as schizophrenia)
2
: such unsoundness of mind or lack of understanding as prevents one from having the mental capacity required by law to enter into a particular relationship, status, or transaction or as removes one from criminal or civil responsibility
3
a : extreme folly or unreasonableness
b : something utterly foolish or unreasonable