“Imply” and “infer” have a relationship that is similar to the one between “talk” and “listen.”  “Imply” corresponds more closely to the talking side of the relationship, and “infer” corresponds more closely to the listening side. A talker can imply; a listener can infer.

When you imply something, there is a meaning in what you are saying or projecting that may be understood by someone else but is not being communicated in a direct manner by you.  If you say “The floor is wet,” you may be implying that your listener shouldn’t walk across it.  If you say “I know where you went last night,” your tone may be implying that your listener was up to some mischief or even immoral activity.

Sometimes, of course, we argue about what we said versus what we implied.  We say, “I didn’t say that!” and the other person says, “Yeah, but you implied it!”  It is possible for us to say something that can be interpreted in a way that we do not intend.  What’s really happening in many of these contentious cases, though, is that the listener is inferring a meaning that we did not intend to imply!

When you infer something, you are on the receiving side of the communication.  Something is expressed to you, and you are finding inexplicit or hinted at meaning in it, or you believe you’ve uncovered some hidden meaning even if, in fact, it isn’t intended by the speaker.

It should be said that both implication and inference are absolutely essential to communication.  It would be uncomfortable, difficult, or impossible to actually say everything that we mean when we say something.  Instead, we trust in our listener’s ability to understand what we’re implying or to infer information from what we say.   For example, if we say “My flight leaves at seven.  I guess I’ll set my clock for 4:00 a.m.,” we intend our listener to understand the connection between these two statements, and we don’t even question his or her ability to do so.  What we are not saying but that we trust our listener to infer from the above sentences, among other things, is that the flight leaves at seven in the morning, that the clock is an alarm clock, and that we need to wake up at the set time in order to have time to get to the airport for our flight.

How would we function if we had to actually say everything we mean?!

Finally, although the discussion here has focused on verbal communication, it should also be noted that both “imply” and “infer” can be used in other contexts.  Either can be used in reference to other ways that meaning can be signaled indirectly or can be deduced, as the following examples will show.

imply

to signal (a meaning) without directly stating such meaning; suggest.

Are you implying that I cheated?

She agreed to do it, but her tone implied resentment.

When she told him he dropped his candy wrapper, she was implying that he should pick it up.

These symptoms imply a weakened immune system.

infer

to conclude or determine on the basis of evidence or logical premises.

From her sarcastic tone, he inferred that she was not pleased to see him.

When the interviewer said she was by far the best applicant for the job, she inferred that the job would be offered to her.

I inferred his motives from the manner in which he made his request.

Seeing the large number of books in her room, I inferred that she was an avid reader.