If an English major graduates from college, must one say,
She has a Bachelor of Arts?
May one instead say,
She is a Bachelor of Arts?
He has a master's
is certainly correct, but might one say,
He is a Master of Science?
If an English major graduates from college, must one say,
She has a Bachelor of Arts?
May one instead say,
She is a Bachelor of Arts?
He has a master's
is certainly correct, but might one say,
He is a Master of Science?
It's not common to say She's a Bachelor of Arts, but I think it would be understood.
It would not be understood if you left out the of Arts.
Note that They're all PhDs is at least as common as They all have PhDs. But I don't think many people would say He's a Doctor of Philosophy.
I don't have a citation, but in the American graduate school where I studied, we were taught (informally) that academic ranks were historically related to old medieval guild structure.
Although today we wouldn't refer to someone as a "Master" because of their M.S., scholars of the past would have recognized someone with an M.A. as a Master in their trade.
It is common to refer to people with a Ph.D as "Doctor", which is an exception to this rule.