Either 'that' or 'who' is correct in this sentence.

Fabio This is an excellent question, for two reasons: 1. It is a controversial question, without a definite answer. So it is interesting. 2. It says something about life: that you can take it at the most superficial level and still be happy, or you can take it at a richer and deeper level. The general superficial man-in-the-street level: - "Who" is used with a person. "That" is used with a thing. So obviously "who" would have potential to be correct, and indeed in oral English people often use "who" for your sentence. The relative pronoun for this sentence, however, replaces the object (the word him) and not the subject of the original "Somone likes or know him", and so it has to be "whom" to be correct. The richer, deeper and intellectually exciting level: - Some grammarians insist on this rule: "Who" should refer to particular persons, while "that" refers to generic persons. And also this rule: "That" is the only defining (as opposed to non-defining) relative pronoun. - So accordingly, "that" is without doubt absolutely the correct word for your sentence.

Fabio For a man at your level of proficiency, the richer option of treating this question in great depth is open. See this brief and simple exposition: http://dannierae.hubpages.com/hub/A-Guide-to-Using-English-Well-Which-That-and-Whom For more on this subject, you could read up all the relevant authorities on grammar. Fowler (as you know, a great authority, and his book has been updated many times) would be particularly insistent that "that" is the one and only correct relative pronoun for your sentence. I am personally more relaxed about this, and believe that like the choice of clothes, the choice of words is a matter of personal taste. And as the Chinese say, "Let a hundred flowers blossom" (though of course at one stage everybody there wore exactly the same clothes and chanted the same slogans). Grammar, like clother however, does tell other people what kind of person one is, but then one could have many personas and identities and indeed a wide and varied wardrobe.

who is correct