I see this phrase used a lot, and always thought it to be incorrect, but I see more and more people using it so I'd like to find out if I am wrong or not.

As an example the following sentences:

The samples were unable to be collected.

Sampling was unable to be performed.

It seems to me that the subject here are the samples or the sampling, therefore it is incorrect to use "unable to be" when they are describing an action that was to be done by someone else.

I would rather say one of the following

We were unable to perform the sampling.

We were unable to collect the samples.

The samples could not be collected.

The sampling could not be performed.

Do these last two have the same meaning?

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    I agree with you. "Unable" implies that the subject has some agency.
    – Hot Licks
    Dec 26, 2019 at 17:28
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    Don't just assume that switching from unable to to can't / couldn't removes the implication of "agency". Native speakers would rarely say This pen can't write or My car couldn't start, for example. Not that this is a "hard-and-fast" principle anyway, as you'll see if you look at some written instances of [things / people] unable to be released. Dec 26, 2019 at 18:16
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    @FumbleFingers I see an inanimate object that is unable to do something as perfectly fine, if it is an object that normally perofms that action for example, like a car starting up vs not starting because there is somethign wrong with the car. My qualm is with the statement that an object is unable to have someone act on it. It is that someone that is unable to act on it. For example "the samples were unable to be collected because the technicians had to prioritize a different task." Would that sentence not be incorrect?
    – Davide
    Dec 26, 2019 at 19:03
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    The fact that a significant minority (24% vs 76%) of competent Anglophones (ie of the usage panel) disagree here {again, AHD}, saying that 'The samples were able to be collected' say is acceptable, proves that there can be no definitive answer ('right' / 'wrong'). Dec 26, 2019 at 19:16

1 Answer 1


Passive voice has a great way of obscuring meaning...which is partly its point. It leaves ambiguous the actor or agent.

I did not do it. vs. It was not done.

So, considering the question, I believe most writers and speakers would consider these phrasings to be equivalent:

The samples { weren't / couldn't be / weren't able to be } collected.

Whether samples themselves have any influence on their ability to be collected, the condition of an object could affect its collectability.

The samples were so degraded, they were unable to be collected.

The samples were so degraded, they were incapable of being collected.

The samples were so degraded, I was unable to collect them.

The sentences really mean the same thing; the third just takes more responsibility.

I agree wholeheartedly with Mr. Ashworth's comment above, that it can't be established if one way is the only "right" phrase grammatically. You can argue whether it sounds wrong to give a quality of able-ness to a thing, but "unable to be collected" and "unable to sing opera" are not quite the same level of capability.

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