The third time I let the erroneous “principle parts” slip into a published post instead of the correct “principal parts,” I began to worry.
Why would I continue to make this mistake even though I know perfectly well that the word spelled principle is used only as a noun and never as an adjective? Principal, on the other hand, is usually an adjective, although it may also be used as a noun:
principle (noun): a fundamental truth; a rule adopted as a guide to action.
The desire to help the helpless is a basic principle of morality.
She lives according to the principle that it is always possible to be kind.
principal (adjective): most important; highest in rank or order.
Dr. Singh is the principal author of the study.
It’s necessary to memorize the principal parts of irregular verbs.
principal (noun): a person occupying the most important position in an organization or activity.
Mr. McCarthy has been named the principal in the lawsuit.
Ms. Washington is the principal at Jones School.
According to Sigmund Freud, when we make an error in speech (“a slip of the tongue”) or an error in writing (lapsus calami), we are being guided by “a subdued wish, conflict, or train of thought guided by the ego and the rules of correct behavior.”
Cognitive psychologists, on the other hand, say that such slips can be caused by mere inattention or lack of knowledge.
Knowing that my errors with principal/principle weren’t the result of lack of knowledge or inattention (I proof these posts at least six times before submitting them), I read further. I think I’ve found my answer in this explanation quoted in the Wikipedia article “Freudian Slip”:
[these errors may be caused by] the existence of some locally appropriate response pattern that is strongly primed by its prior usage, recent activation or emotional change or by the situation calling conditions.
My slip with principal/principle always occurs in the context of writing about the principal parts of the verb. And what are these parts? They are: present, past, past participle, and present participle. I think my brain anticipates the -le of the word participle.
That may explain why I write the term incorrectly, but why don’t I catch the error when I proofread?
Tom Stafford, a lecturer in psychology at the University of Sheffield in England, says that it’s difficult to catch errors because the brain generalizes the simple components of sentences so it can focus on complex tasks, like combining sentences into ideas. We don’t catch errors because we don’t see them.
Writing about typographical errors, Freud cites a case in which an article had been carefully proofed by the author and the editor-in-chief of the paper in which it was to be published; both men were satisfied that everything was correct. The printer’s reader caught the mistake that the other men missed:
Our readers will bear witness to the fact that we have always acted in a selfish manner for the good of the community.
The intended word was unselfish.
Stafford suggests that one way to catch errors to which we’ve become blind is to change the font and colors of the proof copy; changing the visual form makes it easier to see details we would otherwise miss.
It’s also probably a good idea to acquaint yourself with your own particular bêtes noires and be on the lookout for them. Things like mixing up principal and principle.