Saturday, May 23, 2015

What's the Difference Between "Implies," "Entails," and "Suggests"?

You may have heard people say that something “suggests” a particular conclusion, or that something “implies” or “entails” that same conclusion. Further, you may have seen these terms used interchangeably. I am here to suggest that these terms are not so interchangeable.

First, take “implies.” If something implies something else, it means that if the thing doing the implying obtains, then the thing it implies obtains as well (every time!). So, if P implies Q, then every time P obtains, Q does also. A well-known principle in ethical reasoning is that ought implies can.[1] Thus, if someone ought to do some particular action, then he can do that particular action. Because of this, you can see that when you write in a paper, for example, that such-and-such implies this or that, it carries a very strong claim. As you might guess, much of the time (perhaps even most), they don’t mean to say that it implies the conclusion or claim.

I won’t spend much time on “entails,” since some may view this as identical to “implies,” and I wouldn’t hold it against them. There might be a particular nuance to entailment that goes beyond implication (or at least goes about it another way). Take the proposition “I think X is true.” This proposition entails another proposition, namely, that “I exist,” is true. Entailment relations are established between A and B when either A or B is a necessary precondition of the other. So, we label the earlier proposition “B,” and “I exist” as A, and we see A is a necessary precondition of B. Thus, B entails A. However, it’s important to note that it would be wrong to say that A entails B (my existing is not a sufficient condition to guarantee that I think a particular thought!).

Finally, we should see “suggests.” Suggests is most often the word students and people mean when they write “implies.” Here’s an example: “The reticence of the White House to provide a long-form birth certificate implies that the president was not born in Hawaii.”[2] No, it does not. What one would want to write is that it suggests he was not born in Hawaii (and even that is dubious, but at least it’s in principle defensible).

So, I hope this crash course has helped a bit, and remember to choose your words carefully. Why? Because you want to be able to communicate with precision, so that others may know precisely what you are claiming. This will also help you to identify others claims, and to “weaken” them if necessary. If someone is claiming evil entails God’s non-existence, or implies it, you can explain to them this difference and argue them down, by defining your terms, from God’s necessary non-existence merely to the claim that evil suggests God does not exist, and then move from there.

Have any thoughts on this? Leave them below!

[1] In the examples I am offering, it’s not really important as to whether or not you agree with the application of these examples. It’s just to show you what implication, entailment, or suggestion looks like.

[2] Please, please, don’t mistake me for a “birther.” It’s just a primary example.


  1. What the terms "imply," "entails," and "suggests" mean often depends on the context. I

    In philosophy, "P entails Q" means "There is no possible world where P is true and Q is false." The philosophical meaning of entailment doesn't quite match the ordinary English definition, since in the philosophical sense "The existence of a married bachelor entails two plus two equal four" is true, but it is apparently not true in the ordinary English sense.

    Similarly, in the philosophical sense "imply" is potentially much weaker than what you've described here, since it is often used to refer to material implication, i.e. where "P implies Q" just means "It is not the case that P is true and Q is false." For example, "Abraham Lincoln never being President of the United States implies that he was a disc jockey" is true.

    1. Yes, this is right--I appreciate the time and the help! :)


Please remember to see the comment guidelines if you are unfamiliar with them. God bless and thanks for dropping by!