ought. should

Earlier this month, I emailed Merriam-Webster the following question. Editorial Assistant Serenity Carr replied.

Q: Is there any real difference between should and ought? If I tell you that you “ought” clean the house, does that imply the same level of suggestion or seriousness as if I told you that you “should” clean the house?

A: The auxiliaries ought and should are both entered in our dictionaries with usage notes. Ought is “used to express moral obligation, duty, or necessity,” and should is “used . . . to express duty, obligation, necessity, propriety, or expediency.”

The following is found in the synonym discussion at ought in our Unabridged Dictionary:

“Ought and should are often interchangeable and imply the compulsion of obligation, ought more commonly suggesting duty or moral constraint, should applying more to the obligation of fitness, propriety, or expediency.”