I ran into this sentence written by a student:

This is an ordinary anxiety that comes and goes and does not interfere with someone’s life.

I feel that "someone's" should be replaced with one's, but I don't know the rule. When do we say someone and when one?

  • 1
    That's an interesting question. I don't think there is a "rule": it's a usage question. My introspection suggests that we tend use one when we are thinking of a particular person - often the speaker's self. It is a formal or literary equivalent to the colloquial non-referring you - which, confusingly , does not usually refer to the hearer. Where there isn't a particular person in mind, even as an example, I think we're more likely to use someone/anyone.
    – Colin Fine
    Sep 30 '20 at 16:43
  • To an American, using one makes it sound like either a) You're over 80 years old, or b) You're trying to sound British. Most Americans will go for years without using one as a pronoun.
    – The Photon
    Sep 30 '20 at 22:21
  • The use of 'one' to stand in for an unspecified person seems to be related to the French word 'on' which is more widely used than the English 'one' (for instance 'on dit', 'one says' or 'they say'). The French for 'someone' however, is quelq'un(e) which is quite different. I believe that 'one' in this sense is very specific and that your student was using 'someone' in a broader sense than would be covered by 'one', in fact morelike thr French use of quelq'un.
    – BoldBen
    Oct 2 '20 at 3:54


I have no reference for what follows except the foundation given by the dictionary definitions; all the rest is deduction on the basis of inferences of my own and my understanding of English, which, let's hope, will not be found too much at fault. The problem lies in the basic ideas from logic: not anyone will identify the concepts clearly but someone familiar with the basic elements of this theory will perhaps benefit from the connections that are established.

(OALD) someone       a person who is not known or mentioned by name

(OALD) one        (formal or old-fashioned) used to mean 'people in general' or 'I', when the speaker is referring to himself or herself
Note: it is much more usual to use 'you' for 'people in general'.

(SOED) someone       some unspecified or unnamed person; = SOMEBODY

(SOED) one      12 any person of undefined identity, as representing people in general; I, him, her, as an example, a person, anyone.

I believe personally that the difference between "someone" and "one" is to some extent the difference there is between the quantifiers in the mathematical theory of logic. There is bound to be a certain margin of inexactitude (possibly important), but "someone" seems to be often quantifying the enunciation existentially, whereas "one" will quantify it universally. This is embodied to a point in the definitions: we do have "a person" for both, but in the case of "one" this is qualified by "anyone" (all) and "representing people in general" (all), which it wouldn't come to mind to do in the case of "someone".


  • Someone is at the door. (Said otherwise: "There is someone at the door."; this is more or less the logical form "there exists someone at the door" (Proper diction must be forgotten in this task of coding meanings strictly.)
    One is at the door.

  • Tell someone in the audience to explain the problem. (There exists someone in the audience that you can pick and tell to explain the problem)
    Tell one in the audience to explain the problem.
    In the present case the existential characteristic is less salient, rather hard to find in the terms but there is not possibility of a universal quantification, which the impossibility of using "one" tends to confirm.


  • When one is sick one/they goes/go to a doctor. "One" should be be taken as the same person in both cases.
    When someone is sick someone goes to a doctor. "Someone" is not taken as the same person in both cases.
    When someone is sick they go to a doctor. This will do in a restricted context, for instance, that of a team working in an environment at risk. In the most general context, beside using a formal sentence with "one", people use formulations such as "When you are sick you go to a doctor." or "When people are sick they go to a doctor."

    In terms of strict logical quantification this comes down to this: For all people, it is a fact that if one is sick he/she goes to a doctor.


This is an ordinary anxiety that comes and goes and does not interfere with someone’s life.

The use of "someone" in this sentence portends a hard to define lack of generality, when we are in right to expect the greatest generality. Much better will be the pronoun "your" for instance.

  • This is an ordinary anxiety that comes and goes and does not interfere with one's/your life.

In conclusion, we see that from the logical characteristics that can be inferred and from the examples, in the light of existing usage, we tend to find justified the use of "someone" when some individual is concerned and the use of "one" when all are concerned.


To me, "one's" is more used to defined "anyone" - most of the times, it might include the author or suggest that we are not quite sure who indeed.

"Someone's" would imply somebody else's - hence your/ their, etc. The author here might not be so involved...

Just putting in my 2 cents here though. It's all quite subjective per se.


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