that of

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In the past few days, I keep seeing people misuse the phrase "that of" in the same kind of way, apparently for emphasis. Like this:

* My primary concern is that of earthquakes.

Where the speaker meant to say that their primary concern is earthquakes themselves; but that's not what "that of earthquakes" means.

Here's one possible way to test whether you've incorrectly put "that of" in a sentence that has the structure "My A is that of B":

  1. Replace "that of" with "the A of". (* "My primary concern is the concern of earthquakes.") Or replace "that of B" with "the same A as B's". (* "My primary concern is the same concern as earthquakes's.")
  2. If the sentence doesn't read smoothly, then you've probably misused "that of."

The problem with the above test is that there are some borderline-inappropriate uses that pass the test:

* My subject tonight is that of grammar.

* The company's core business is that of computer graphics.

In both cases, you could argue that the sentence is correct, and both cases sort of pass my above test: "My subject tonight is the subject of grammar"; "The company's core business is the business of computer graphics." But in both cases, the "that of" is redundant.

So here's another test, probably better: just cut "that of" from the sentence, and see if the sentence still makes sense; if it does, then you were probably misusing "that of."

I think there's a subject/object confusion at the heart of the misuse; in the standard use of "that of," the B in the phrase "that of B" is a person or organization that owns (or to which can be attributed) the thing named by A.

Here's an example of how to use "that of" correctly:

His premise was that of Newton: that matter and energy are distinct.

In other words, his premise was the same as Newton's premise.

I imagine this is yet another case where my prescriptivist side will have to learn to live with the new phrasing; I suspect it's becoming more widespread over time. But it bugs me.

Of course, for all I know, the usage I'm objecting to has been around longer than I have; I don't currently have any easy way to check on that. If any of you know, let me know.

(Wrote this back in March, but neglected to post it.)