Is using "and/or" recommended for formal writing, or is it frowned upon?

Question

Is using "and/or" allowed in formal writing? If not, is there general way to represent the OR binary operator with as little space as possible in written English?

Answer 1

Please do not use "and/or" in either formal or informal writing.

In common English, the "or" is a "non-exclusive or" which means "either A or B, or A and B". When I say "I can have a banana OR I can have coffee" then I am also OK with having both. Having a banana does not prevent me from having coffee.

The "exclusive or" which means "A or B, but not both" properly is used in legal documents - where the text must be completely unambiguous - and in logic circuits, where logic gates differentiate between "or" and "exclusive or" which is often denoted as "EOR" or "XOR" to distinguish it from "OR".

Unfortunately, the use of "and/or" in English writing has proliferated in recent decades. I attribute this trend to a growing laziness in written communications - not taking the time to structure sentences to be clear, but just tossing in an "and/or" to cover the lapse.

But a basic rule of good writing is to not write something that you would find awkward if speaking aloud. And I don't know anybody who says "I'm going to buy some food at a grocery store 'and/or' a bakery"!

Answer 2

Using "and/or" would be frowned upon in formal writing because it is inelegant.

I'm not convinced it either saves space or clarifies anything.

"Or" is ambiguous, because it can mean 'either this or that but not both' or 'indifferently this or that.'

A good practice is simply to make sure the whole sentence makes the expresses the meaning you want.