Can anyone explain why an author used the structure with "of" in the sentence below and how it can be justified:

We do not know of any way to be certain that leads to success.

I would write it as

We do not know any certain way that ..., or as

We do not know any way to be certain that ....

I looked to the "of" definition in Collins Dictionary, but still have not found the way the author was thinking.


There's a fairly regular process where a transitive verb (like know or shoot, which has a subject and an object) can be weakened in its effect by taking the object and rendering it as an oblique argument (in a prepositional phrase) instead. So:

He shot me

Entails that I got hit.

He shot at me

Implies that he missed me.


I know him

Entails that I have met him, that my knowing him is quite strong, whereas:

I know of him

Implies that perhaps I haven't met him, but I have heard of him or that I'm broadly aware of his existence over the grapevine.

In a dictionary, I'd suggest looking for this usage under 'know' rather than under 'of'. It might be there as a phrasal entry. In fact having just looked up the Oxford, I see it as its own subentry under 'know':

To be aware or cognizant of (a person or thing as existing, an event as having occurred, etc.).

And it has the additional information:

Sometimes contrasted with know, as implying little or no knowledge of anything beyond the existence of the person or thing.

As a great example, there was a Simpsons episode in which Bart goes to a new school (because Homer got a job working for an international villain) (source):

4th Grade Teacher: [On Bart's first day in his new school the teacher discovers he can't read cursive handwriting] So, you never learned cursive?

Bart: Well, I know "hell" and "damn" and "get ben..."

4th Grade Teacher: No, no! Cursive handwriting! Script! Do you know multiplication tables? Long division?

Bart: I know of them.

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