1. We hope this digging method can be useful to those workers.

  2. We hope this digging machine can be useful to those workers.

Is can epistemic or dynamic here?

2 Answers 2


In these sentences you arrive at a point where it is really neither useful or accurate to speak of can itself being epistemic.

In the first place, every modal verb exhibits some degree of epistemicity in every use. A modal verb marks the eventuality it puts forward as something which has not happened (yet); consequently, it inherently involves and ‘qualifies the speaker’s commitment to the truth of the modalised proposition’—the CGEL’s definition of epistemic modality (p.52).

In the second place, epistemicity is not entirely determined by the modal verb itself (CGEL discusses this under the rubric of ‘modal harmony’, p.179). John Feminella points out that ‘The “hope” is the key part here’. I agree, and I suggest we should take this a step farther: it is hope, not can, which confers the primary epistemic sense on the sentence. What we can (!) say is that can harmonizes with both epistemic and non-epistemic intentions.

I am inclined, therefore, to say that a dynamic sense of can is primary here. The strictly epistemic sense of can is equivalent to must, and it is employed in this sense only in the negative: we say It cannot be that he has deceived me, meaning that it is impossible, it must be false, but not It can be that he has deceived me: must or has to (or some longer expression) is needed to express modal certainty here, and can expressing modal possibility requires could.

What the writers hope is that the method/machine will prove to be capable of helping. That capability, the core dynamic use of can, is can’s specific contribution to the sentence.

Huddleston and Pullum, The Cambridge Grammar of the English Language, 2002.
Except in echoic instances, when a speaker denies a previous epistemic use of the negative: ‘That can’t be true!’ —‘On the conrary, it can be and is!’

  • I had a similar idea on this; this is a marginal area between a clear-cut answer and personal opinions. What's meant by (!) in your answer? I think can (!) there suggests a dynamic possibility (what is reasonable).
    – Kinzle B
    Sep 14, 2014 at 3:23
  • @KinzleB I grow more and more conscious that precise technical terminology eventually runs up against situation where it just doesn't tell you anything useful or even relevant. As for the screamer, it just struck me as - amusing? - that I had to emphasize the very word we are discussing. Sep 14, 2014 at 3:28
  • I agree. Technical analysis has its shortcomings. Sometimes I doubt if I'm on the right track of learning English. At my current level, how can I improve my English further?
    – Kinzle B
    Sep 14, 2014 at 3:39
  • @KinzleB Read. Listen. Write. Talk. Engage with the language. She doesn't really care what it's about, as long as you're interested in it she'll teach you something useful every time. Sep 14, 2014 at 3:45

The sentence is best understood as "We hope that the digging method turns out to be useful". Since this is a speculative version of "can", it's an epistemic verb. The speaker is entertaining the possibility that we're in a universe in which the digging methods are useful.

Note that modal verbs usually exhibit a number of different facets of meaning, thanks to the natural and wonderful ambiguity of language. But I think the "hope" is the key part here. Again, the speaker is entertaining a possibility of some future state, namely, one in which the digging method is useful. That's an epistemic usage.

If, instead, it was "The digging machine can be useful to workers", that's a dynamic usage: the digging machine has the capacity or capability to be useful. (We're not entertaining a future state there; we're describing things as they are.)

  • You are suggesting inanimate subjects cannot be used with a dynamic can. What about this one: "Modern launch vehicles have more efficient engines and can launch a heavier payload: typically as much as two per cent of their launch weight."?
    – Kinzle B
    Sep 13, 2014 at 14:56
  • I wasn't suggesting that, only saying that the first (epistemic) case is more likely here. The digging methods aren't doing the work -- the workers are. Sep 13, 2014 at 15:24

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