In Logic Or signals a Logical disjuction it means an inclusive OR.

I get into trouble when saying OR and mean inclusive OR.

Is the person Black or Male?

I usually get this considered a "wrong" question.

How can I make it explicit that I mean inclusive OR, in a natural and formal way?

And/or does not seem formal or natural.

  • 5
    In contemporary English you can say "and/or".
    – The Photon
    Commented Jul 29, 2019 at 0:51
  • @ThePhoton How formal and natural is it? Commented Jul 29, 2019 at 1:15
  • 2
    It's very common in writing, but not particularly natural in speech. If you want a more natural idiom for speech, you have to say "black or male or both".
    – The Photon
    Commented Jul 29, 2019 at 1:22
  • @ThePhoton Will you expect any PhD thesis or Post-PhD researches, Habilitation or Fellowship thesis in Oxford University in the departments of Medicine, English or Law to contain and/or unless it was a Thesis studying precisely And/Or's usage in the English language or Logical disjunction? Language in those texts would be both formal and natural. Anything else is excluded for being mostly informal. Commented Jul 29, 2019 at 1:53
  • 1
    In normal speech, or can be treated either inclusively or exclusively. It depends on context and the interpretation of the listener. I've always considered it to be inclusive, and only used explicit terminology when I've wanted to express an exclusive or. But the given answer is correct in terms of explicit language to use for an implicit or. (I personally despise the use of and/or, although I acknowledge that many have no problem with it.) Commented Jul 29, 2019 at 18:22

3 Answers 3


If you wish to communicate so that what is understood by the people to whom you wish to communicate is what you mean, then I urge you never to think of relying on formal logic, however unambiguous it might seem to you.

So the problem with "Is he black or male?" is not just ambiguity in the ears of the listeners (because most listeners will not be aware of the different types of 'or') but is that the question is bizarre. You have to spell out what you mean.

I share Jason Bassford's hatred of 'and/or' on stylistic grounds, but there is another objection: a question with 'and/or' in it is highly likely to be perceived as confusing, particularly in speech. Complicated logical questions do need to be posed clearly, and that means with repetition and redundancy.


The specifity of "or" is conditional on context. new or old cannot be inclusive. broken or otherwise dysfunctional is basically just dysfunctional. thirsty or hungry is not mutually exclusive, though a little redundant.

I am not sure what the rejection of black or male implies about racial hyper-sensitivity. The answer Both! would be well acceptable. And there is no need to alter the question, if the addition [...] or both? is chiefly implied (this is achieved through intonation, which is missing in writing, but several alternatives would be available).

  • I have a problem reading your answer. Commented Aug 3, 2019 at 22:46

In contemporary English, "and/or" is becoming fairly common, in both writing and speech.

An alternative that might come across more naturally in some contexts is to ask something like "Is the person black or male or both?" There's still an inherent ambiguity about whether you want a yes/no answer, or if you want an answer from the three alternatives offered. However if you want a yes/no answer and the other person answers with "both", you can still interpret that as a yes.

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