on principle
Because of one's values or beliefs.
All human actions are equivalent and all are on principle doomed to failure. Jean-Paul Sartre
One never knows whether people have principles on principle or whether for their own personal satisfaction. Karel Čapek
I study chess eight hours a day, on principle. Alexander Alekhine
Change based on principle is progress. Constant change without principle becomes chaos. Dwight D. Eisenhower
Ethics are so annoying. I avoid them on principle. Darby Conley
I have never opened with the QP – on principle. Bobby Fischer