Is Assertion Closed Under Entailment? Assertion and Presupposition

Suppose a person asserts that p. Suppose also that p entails q. Does it follow that the person asserting that p thereby asserts that q?  If so, and if p and q are any propositions you like, then assertion is closed under entailment.  If assertion is not closed under entailment, then there will be examples in which a person asserts that p, p entails q, but the person does not assert that q.

By 'entailment' I understand a relation between propositions. P entails q iff it is impossible for p to be true, and q false. By 'assertion' I mean a speech act, an act of asserting, a concrete, datable, linguistic performance, not a proposition.  By 'the content of an assertion' I mean the proposition expressed  when a person makes an assertion. A proposition is not the same as a sentence. 'The war has come to an end' is a sentence in English. 'Der Krieg hat zu Ende gekommen' is a sentence in German.  The sentences are different, both at the type level and at the token level. And yet they can both be used to express one and the same thought. That same thought is the proposition.  By 'thought' here I do not mean an occurrent episode of thinking, but the accusative (direct object) of such an act of thinking. You could also call it a 'content' although that term is ambiguous for reasons I won't go into now.

Preliminaries aside, back to our question.

That James no longer works for Amazon has among its entailments that James worked for Amazon, that someone named 'James' worked for Amazon, and that someone no longer works for Amazon.

Now suppose I assert that James no longer works for Amazon.  Do I thereby assert that James worked for Amazon?  I say No.

Here is a more striking example. Sophomore Sam asserts that there are no truths.  The content of his act of assertion, namely, the proposition that there are no truths, entails that the content of his assertion is not true.  But surely the latter is no part of what Sam asserts. 

So assertion is not closed under entailment.

Suppose that Tom asserts that he is glad that Trump beat Hillary.  The content of the assertion entails that Trump beat Hillary. But that Trump beat Hillary is not what Tom asserts.  We can say that Tom's act of assertion presupposes that Trump beat Hillary.  But neither Tom nor his act of assertion is a proposition. So if Tom's act of assertion presupposes that Trump beat Hillary, then presupposition is not a relation between propositions, but a relation between a non-proposition (a person or his speech act) and a proposition.

On the other hand, that Tom is glad that Trump beat Hillary entails that Trump beat Hillary. This is a relation between propositions and it makes some sense to say that the first presupposes the second.

This raises a question. Is presupposition primarily something that people do, or is it primarily a relation between propositions?

Comments

[The Bad Ostrich]

Assertion: ‘James no longer works for Amazon’.
Negation ‘It is false that James no longer works for Amazon’.

Is the negation analysed as the disjunction ‘James still works at Amazon or he never worked at Amazon’?

If so, the assertion must be analysed as the conjunction ‘James does not work at Amazon and he once worked at Amazon’, which contradicts you.

If not, and given either the assertion or the negation is true, it follows that necessarily James once worked at Amazon. But that is surely false.

[Brandon]

It seems that Sophomore Sam's problem does provide a reason to doubt this, but I am not sure I follow you on James and Tom, and for similar reasons so I'll focus on James.

If you utter the sentence: 'James no longer works for Amazon' I take that to be necessarily saying the same thing, propositionally, as the compound sentence 'James once worked for Amazon, and James does not currently work for Amazon.'

And necessarily so. For if one were to suggest that what you are meaning can be conveyed as merely 'James does not currently work for Amazon', that would be simply incorrect as it does not account for the '...no longer...' in your original statement.

In other words, I cannot fathom how the proposition part 'James once worked for Amazon' is not necessarily wrapped up in the object of thought held by the party uttering the words 'no longer' to begin with.

I see how Sam's slip presents a problem; I just don't see how we can use James or Tom.

[BV]

Thanks for the comment, Brandon.

Suppose you and I are talking about Peter. I say that Peter stopped smoking and you contradict me by saying that Peter did not stop smoking. Now *Peter stopped smoking* entails *Peter smoked & Peter does not now smoke.* If that conjunctive proposition is what I assert, then what you affirm is its negation, namely *Either Peter did not smoke or Peter now smokes.*

But that is not what you assert when you contradict me. What you assert is that Peter now smokes. Therefore, the content of my assertion is that Peter does not now smoke. I assert that Peter does not now smoke and I presuppose that he did smoke. You assert that Peter does no smoke and you presuppose that he did smoke. Two different assertions, one and the same presupposition.

Ergo, there is a difference between assertion and presupposition. The test for presupposition is survival under negation. The proposition that Peter did smoke survives the change from my assertion to your denial. So that proposition is both your presupposition and mine.

Now if that is right, then assertion is not closed under entailment: If S asserts that p, and p entails q, it does not follow that S asserts q.

If a man named 'Trump' beat Hillary, then there is a man named 'Trump. But if I say that a man named 'Trump' beat Hillary, I presuppose that there is a man named 'Trump' and I assert that this man beat Hillary.

Alles Klar?

[The Bad Ostrich]

So excluded middle is false? Being the case that p and not being the case that p do not exhaust all the possibilities that there are?

If you say that James no longer works at Amazon then you are saying the world is now a certain way. But if I deny what you say, I rule out every possible state of the world that is that way, but allow all else. Surely excluded middle holds. If I deny what you say, I do not rule out anything except what you say, but allow everything else.

[Brandon]

'Alles Klar?'

Almost. I will need to think more about the survival under negation, and take some time with this.

But I must tell you: I just cannot escape the sense that there is a semantical sleight-of-hand hiding in this, and I think the locus of it at the point where you write 'What you assert is that Peter now smokes. Therefore, the content of my assertion is that Peter does not now smoke.'

I find it curious how the propositional content of the speaker's assertion can be shaped by the interpretation of the recipient, as though, by some interpersonal alchemy, part of the semantic content will vanish into thin air.

Consider this.

Sally and Jenny are having a conversation about Peter (all teenagers) recently stopping smoking, and it occurs exactly along the lines that you sketch out above. Lets say that the exchange takes place during a larger discussion where Sally is trying to convey the point to Jenny that Peter is serious about saving money, and that not buying cigarettes (anymore) helps him save, etc. This added context isn't necessary, but just a plausible situation where your exchange can occur and the 'semantical alchemy' could take place without much violence to the larger meaning of the conversation. Then I can see the situation playing out as you state and we can trim it down to 'the content of Jenny's assertion is that Peter doesn't smoke'. Her point is made.

But say Peter's mom Alice overhears the conversation from the next room and her immediate reaction is: 'What! Peter smoked!? What was my Peter doing smoking?' She would zero in on the 'no longer' and inject her meaning into it. It seems very curious how the semantical status of Sally's sentence (phew!) can depend on when Alice decides she wants to dust the blinds in the next room.

It seems to me that all of this comes upstream from your well taken point of 'survival under negation'. I ask you: by whose negation? Jenny's or Alice's?

If one cannot control how one's total propositional content travels into the world, I cannot see how we can ever speak of 'meaning' in a sense narrower than what could be gleaned by any recipient who could soundly interpret any part they happen to find useful.

[Greg Bechtel]

I am having trouble understanding why someone would be attracted to the view that assertion is closed under entailment. The view seems easily dismissed, but I suspect I may simply misunderstand it. Do you agree that the following are consequences of this position?

For any propositions P Q, P entails (P or Q). On this view then, when I make an assertion whose content is P, for each proposition Q there is, I assert a disjunction one of whose disjuncts is Q. Perhaps we can even take Q to be the conjunction of every proposition, if there is such a conjunction.

Also, If I assert a contradiction, I thereby assert every proposition, since contradictions entail every proposition. Or consider mathematical truths. Since such truths are necessary, they are entailed by every proposition. Thus, I must on this view assert every mathematical truth, whenever I assert anything. Or, take the pair of propositions 'God exists' and 'it's not the case that God exists'. One of them is necessarily true. One of them, then, is asserted each time any assertion is made by anyone.

A further consequence of the above is that each of us makes assertions which: we do not know, we cannot know, and which we cannot even entertain since, plausibly, there are necessary mathematical truths so complex that no human being could possibly so much as begin to get that mathematical proposition into their heads. But doesn't it sound jarring that one regularly asserts propositions which no one could entertain, articulate, or even write down?

-Greg B.

[David Brightly]

Hello Bill, and a Happy New Year to you.

Ed says,

But if I deny what you say, I rule out every possible state of the world that is that way, but allow all else. Surely excluded middle holds. If I deny what you say, I do not rule out anything except what you say, but allow everything else.

Suppose you claim the conjunction A∧B. Ed can deny this by asserting ¬B. This rules out B, which is more than the A∧B that you say. And it allows just ¬B, which is less than the everything else to what you say, which is ¬(A∧B), ie, ¬A ∨ ¬B. To deny A∧B does not require asserting its negation. Excluded Middle stands.

[BV]

George B. Thanks for the interesting comments.

>>For any propositions P Q, P entails (P or Q).<< No doubt. And as you say, Q could be some monstrous conjunction.

In the SEP article on assertion one finds this: ". . . a common intuition about a central feature of assertion: explicitness. On this intuition, only the content that is explicitly expressed is asserted . . ." I share that intuition.

Suppose I assertively utter 'Trump won the election.' The explicit content is the proposition expressed by 'Trump won the election.' That alone is what I assert, and not it together with all its entailments. Surely it would be absurd to think that when one asserts that Trump won the election, one asserts that Trump won the election OR Q, where 'Q' picks out the conjunction of all propositions.

The formal logic of your third paragraph is of course correct. From a contradiction, anything follows. Right. And necessary truths are entailed by any proposition, true or false. But it doesn't follow that if I assert that Trump won, then I am asserting that Trump won and that 2 + 2 = 4.

I just now realized that you are agreeing with me! Excellent.

A better question to ask is whether assertion is closed under relevant entaillment. Thus *Kepler died in misery* relevantly entails *there was a man named 'Kepler.* My point is that the second prop. is presupposed not asserted.

[Greg Bechtel]

Thank you for your response, Dr. Vallicella. Yes, I do agree with you. I want to preface the following comment by saying I'm just a laymen reader of your blog and am likely out of my depth here. Yet:

The implausibly of the View we both reject - that assertion is closed under entailment (ACE) - largely derives from the strength of the entailment relation, at least when read as "P entails q iff it is impossible for p to be true, and q false." On standard assumptions together with this reading of entailment, necessary truths are entailed by every proposition, and necessary falsehoods entail every proposition.

Perhaps there is a view in the neighborhood of ACE which would be more defensible. Rather than entailment, it might be more defensible to claim that assertion is closed under some other relation. You suggested relevant entailment which I don't know about. But I'd like to suggest substituting a relation of propositional analysis, where propositional analysis just means something like putting a proposition in conjunctive normal form or somehow reducing it to its atomic components. Maybe call such a view ACA. Again, I readily admit I don't really know what I'm talking about, but my suggestion can be summed up like this:
Unlike myself or you, one who is attracted to ACE might do well to drop the entailment relation and replace it with some weaker relation which involves a notion of containment of sub-propositions or component propositions.

As an example, where on ACE, when I assert 'Some white cars are fast' I thereby (implausibly!) also assert the Fundamental theorem of algebra, on ACA the assertion 'Some white cars are fast' guarantees only (and more plausibly) that I have asserted something is a car, is white, and is fast.

Of course, while entailment is too strong, this relation might be too weak to do justice to your opponent's intuitions. In fact, it looks trivially true to me that assertion is closed under some relation of analysis, and so probably won't help matters. Anyhow, thank you for considering my comments. I'm grateful for your blog and learn from it daily

-Greg B.