Two words in English often cause confusion: principal and principle. After all, they have exactly the same pronunciation! You can easily figure out which one to use like this. See if the word, chief, would also work. Let’s think about a few sentences:
- The principal investigator is responsible for submitting the final report.
- I wouldn’t do that because it’s against my principles.
- The principal cause of the failure was a design error.
- We used proven principles of instructional design to create this class.
- I agree with you in principle, but I need time to think about it.
- The board chose Mrs. Desai to be the school’s new principal.
- The Peter Principle states that an employee will rise to his or her level of incompetence.
It’s easy to see that chief would work in the first, third, and sixth sentences. Perhaps it’s not exactly the word you’d want to use, but the sentence makes sense:
- The chief investigator is responsible for submitting the final report.
- The chief cause of the failure was a design error.
- The board chose Mrs. Desai to be the school’s new chief.
As they sometimes say, the chief is your pal. Use principal when it means chief; otherwise use principle.
And when it comes to a loan, remember that the chief thing you tend to think about is the money you borrow rather than the interest. That’s why financiers talk about principal as opposed to interest.