For example:

  1. Computers are important research tools
  2. Computers are an important research tool.

Does anyone know how to distinguish between (1) and (2)?

  • What do you mean by "distinguish"? Are you asking the difference in meaning, or difference in usage? Or both?
    – Andrew
    Apr 23, 2019 at 16:36
  • The first treats computers as discrete objects. The second treats them as a class or set of objects. The meaning is the same. Apr 23, 2019 at 18:25
  • Thank you Ronald, I still have a question. You said that the meaning is the same. Why we say "Horses are useful animals." but can't say"Horses are a useful animal." ? Apr 24, 2019 at 13:49
  • @ChaiMinChun Horses are a useful animal isn't strictly ungrammatical, but in this construction, most people would expect the word horses to refer to a collection of individual horses, and that introduces a stumble when reading. In contrast, it would be more widely acceptable to say something like the subject is horses or the problem is cars. because there it is clear that you are referring to the concept of horses or cars, and not to specific horses or cars.
    – choster
    Apr 24, 2019 at 22:52

1 Answer 1


There are different ways of expressing the same idea:

  1. "Computers are important research tools."

This is a straightforward sentence telling us something that computers (all of them) are. Each one is an important research tool, and so all of them "are important research tools."

  1. "Computers are an important research tool."

This statement, as Ronald Sole points out in his comment, treats computers as a class or set of objects, and equates them, as a unified group, to one thing, "an important research tool."

You could also phrase the concept like this:

  1. "A computer is an important research tool."

That is a statement about one computer, but since it is framed as a generalization about "a" computer, it isn't limited to a specific one, and must be true about any computer.

Yet another way to put it is:

  1. "The computer is an important research tool."

Here you are referring to the whole general category of computers collectively as "the computer", and identifying that whole group of entities as "an important research tool."

So to answer your question, yes, some philosophers and other theoretical types would be able to distinguish minutely different shades of meaning between sentences (1) and (2), and also (3) and (4). But for regular people using them for everyday communication, all four sentences really just say the same thing.

  • Thank you Lorel, I still have a question.You said that sentences (1) and (2) for regular people just say the same thing. Why we can say "Horses are useful animals." but can't say"Horses are a useful animal." ? Apr 24, 2019 at 5:40
  • 1
    Hmmm. It might be b/c a horse is literally and concretely 1 animal, and it bothers us to hear many animals so obviously equated to just one beast. In the computer examples, the equivalence was to something much more abstract ("research tool"), and it doesn't sound so jarring to say many computers = a single "tool". More concrete would prob. not work here: "Hammers are an important construction tool."--uhhh, ... no. But "Horses are your farm's most important asset." sounds fine. ...in truth, if you didn't point it out, I'm not sure I would have noticed a problem w/ "Horses are a useful animal."
    – Lorel C.
    Apr 24, 2019 at 14:15
  • Thank you so much Lorel, I think my problem has been solved. Apr 24, 2019 at 14:45

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