Verb
defeat the purpose (third-person singular simple present defeats the purpose, present participle defeating the purpose, simple past and past participle defeated the purpose)
To undermine the act of doing something by having an opposite effect; to nullify.
I went to a bookstore and asked the saleswoman, 'Where's the self-help section?' She said if she told me, it would defeat the purpose. George Carlin
I went to a bookstore and asked the saleswoman, 'Where's the self-help section?' She said if she told me, it would defeat the purpose. Steven Wright
Words too familiar, or too remote, defeat the purpose of a poet. Samuel Johnson