Inour most recent episode, we talked about modals: words like “can”, “may”, “must”, and more. In particular, we took a deep dive into the semanticsof modal verbs. But we didn’t talk much about how they fit into the structures of sentences, and this seems to leave open some important questions. For starters, we made the claim that — in terms of their meanings — modal verbs combine with whole sentences, and not just the verb phrase that follows them. After all, the meaning of the sentence in (1a) seems to correspond to (1b).
(1a) The Observers must report to their commander.
(1b) It must be that the Observers report to their commander.
On the face of it, it seems weird that subjects in modal sentences appear separate from the main verb phrase, as in (1a), while being interpreted as though they were right next to them, as in (1b). It looks like this could be a big problem for our overall theory.
Thankfully, when we take into account some of the important discoveries we’ve talked about in past episodes, like the VP-Internal Subject Hypothesis, this problem goes away pretty quick. If it’s true that, in general, subjects start off somewhere insidethe verb phrase, and only latermove to a spot that’s higher up (and more to the left, at least in English), we can suppose that the meanings of sentences — modal and all — are simply computed beforethe subject starts moving around, instead of after.
But, this still leaves us wondering what part of the tree modal verbs typically call home. If you want to know more about how to set that up, keep reading!
The liminal zone between syntax and semantics (especially when we’re drawing mid-twentieth century trees) makes me completely bonkers. I don’t see the point of doing this kind of structural, ideologically-coded work when what’s at issue are conceptual relationships.
I mean, I guess I understand that it would be nice to represent relationships of meaning systematically and in terms of order, but I feel like the various models still don’t account for (any maybe shouldn’t) all the nuance of which human language is capable.
I’m always so much more comfortable using syntax to approach grammars and glosses rather than as a generative and constitutive system of language.
Please correct me if I’m wrong. I would love to hear some arguments for the coordination of semantics and syntax in this way. Or an explanation of how theoretical syntax improves our (english-speaking) understanding of semantics. OK, go!
So this is actually a really deep and interesting question that gets to the heart of linguistic theorizing, and even science in general. We’re going to try to do this without going through all the examples from the episode and the original post, but I hope it still makes sense!
Let’s start with what we said in our post about the apparent tension between modal verbs combining with whole sentences on a conceptual level, while being sandwiched in between subjects and verb phrases on a syntactic one. We could, in principle, rework the meaning we’ve assigned to modal verbs to make them work without the added complication of subjects moving around inside sentences. That is, we could paint a superficially simpler picture of how the meanings of these sentences come about. But removing the complexity from one part of a theory often ends up hiding it in some other part of that same theory. And so, even though we could tweak our definition of modal verbs to work in a syntactically simpler system (i.e., one that very literally has fewer moving parts), that new definition is made more complex. To get a bit technical, it goes from a simple characteristic function to a somewhat fancier function-valued function, which is a kind of higher-order function (representing a kind of logic that’s a step above the ordinary).
It turns out we can’t have both a simple syntactic representation, and a simple semantic one, because the order that one thing happens in influences the order that another thing happens in, and ignoring this would be like trying to put your pants on after putting on your shoes. So, the theory as a whole becomes simpler in one way, but more complicated in another. It’s this kind of unavoidable choice that has to be made, where to put the complexity, and we made it the way we made it because we already have other reasons to think it’s actually the syntax that’s complicated in this case, and not the semantics.
On supposing that there are actually two different spots in any given syntactic tree where modal verbs might live, depending on their flavour: this is actually practically useful. We guessed that knowledge-based modal verbs are relatively high up in the structure of any given sentence, while rule-based modal verbs are much lower down. To put it another way, we supposed that some modal verbs are structurally closer to the subject, with lots of room down below, while others are structurally closer to the verb phrase, making things more cramped. And this actually ends up having observable consequences, since in the case of higher, knowledge-flavoured modal verbs, there’s room enough between them and the verb phrase for all kinds of auxiliary verbs, like in “Peter must have been telling the truth.” But with lower modal verbs, that are about rules instead of knowledge, and which don’t leave as much space between themselves and the verb phrase, we don’t end up seeing all these intervening auxiliary verbs, as in “Peter must tell the truth.” So it looks like there’s some reality to there being a couple of different places for modal verbs to hang out, which has a real effect on the kinds of sentences we can build. And it’s worth mentioning at this point that we do find sentences with two modal expressions in them, and that when we do, the knowledge-y modal always seems to come before the more rule-ish one, like in “Peter must have to tell the truth.” We might be able to explain all these facts using simpler structures, but chances are that the meanings that come out of it get pretty sophisticated pretty quickly.
Finally, let’s look at what we said about the internal syntax of modal phrases. On one level, it’s just useful to represent things this way, to be able to visualize all the pieces and parts that go into building the meanings of these sorts of sentences. But in principle, we could simplify both the definitions of modal verbs and their surrounding structures, without any obvious trade-offs. And some linguists actually go ahead and do this. However, there are reasons to think that (for example) the modal base is on some level really present inside the trees we build in our heads. For one, sometimes the modal base is actually pronounced, as the topic of the sentence: “In view of the rules, Peter must tell the truth.” But even when it’s left out, because the context makes it obvious what’s being talked about, there are still reasons to suppose that, at a minimum, there’s something there in the tree that corresponds to it. In particular, when we get to talking about conditional (if-then) sentences like “If he wants to stay out of trouble, Peter must tell the truth,” it’s useful to think of that “if” part of the sentence as restricting, or limiting, the modal base. And that’s much easier to do if the modal base is, although unpronounced, somehow actually there in the tree. It could probably be done other ways, but that likely means supposing there are a couple different kinds of modal verbs – some that fit comfortably into conditional sentences, and some that don’t – and I’m not sure there’s any good reason to think that we have twice as many modal verbs in our vocabulary as we think we do!
And we definitely take the point that, as we’ve presented things, we don’t even come close to fully capturing all the variety and nuance found in human language. Unfortunately, there just isn’t enough space to cover everything in one go. But we’ll for sure be back to talk more about modal verbs in the future, and what we find when we look at other languages. It’s a gigantic and fascinating topic, with many different dimensions to it! And with the basics out of the way, we can now start to get to the good stuff! ^_^
Inour most recent episode, we talked about modals: words like “can”, “may”, “must”, and more. In particular, we took a deep dive into the semanticsof modal verbs. But we didn’t talk much about how they fit into the structures of sentences, and this seems to leave open some important questions. For starters, we made the claim that — in terms of their meanings — modal verbs combine with whole sentences, and not just the verb phrase that follows them. After all, the meaning of the sentence in (1a) seems to correspond to (1b).
(1a) The Observers must report to their commander.
(1b) It must be that the Observers report to their commander.
On the face of it, it seems weird that subjects in modal sentences appear separate from the main verb phrase, as in (1a), while being interpreted as though they were right next to them, as in (1b). It looks like this could be a big problem for our overall theory.
Thankfully, when we take into account some of the important discoveries we’ve talked about in past episodes, like the VP-Internal Subject Hypothesis, this problem goes away pretty quick. If it’s true that, in general, subjects start off somewhere insidethe verb phrase, and only latermove to a spot that’s higher up (and more to the left, at least in English), we can suppose that the meanings of sentences — modal and all — are simply computed beforethe subject starts moving around, instead of after.
But, this still leaves us wondering what part of the tree modal verbs typically call home. If you want to know more about how to set that up, keep reading!
In our old system, we might’ve been happy dumping all our modal verbs into the bucket labelled “inflection.” And this seems reasonable at first, since like other kinds of inflection (e.g., tense, aspect, voice), modality sometimes appears as an affix on the verb.
(2) Turkish: gel-me-meli-siniz
come-ɴᴇɢ-ᴏʙʟɪɢ-2ᴘʟ
‘You ought not to come.’
But this probably isn’t the most sophisticated picture of how sentences get put together, given that concepts like tenseandmodalityare pretty different from each other. Moreover, if they really were members of the exact same category, you might not expect to find them showing up in the same place at the same time, like how a coin can’t land both heads and tails; in fact, most modal verbs have both present tense (may, can, shall, will) and past tense (might, could, should, would) forms.
So, it probably makes more sense to think of modal verbs as appearing either somewhere just below, or somewhere just above, a dedicated tense phrase (TP).
It might even be both, given that modal verbs seem to interact with tense in subtly different ways, depending on their flavour:
(3a) Olivia could have used her powers, but she didn’t want to.
(3b) Olivia could have used her powers, but I haven’t found out yet.
After all, the sentence in (3a), which is saying something about Olivia’s abilities, seems to be about what was possible in the past(i.e., circumstances might be different now), whereas the sentence in (3b) says something about the speaker’s presentstate of knowledge. In other words, it looks as if the same modal verb either falls under the influence of the past tense, or else manages to escape it, depending on how it’s interpreted. This suggests there might be modal phrases both below and above the tense phrase.
Lastly, it’s important to say something about how modal phrases actually get their meanings, and what that says about their internal structure. In the episode, we gave the modal verb “must” a meaning that looked like this:
(4) “must” = λ B . λ p . B ⊆ p
Reading it from left to right, it says that a modal verb first combines with some contextually defined modal base B — whose job it is to give the flavour, like whether it’s about belief or ability — and then goes on to combine with the sentence p, saying of the two that the set of worlds described by the base is a subset of the set of worlds described by the sentence. The modal base, then, is kind of like a pronoun; it’s like “they” or “them,” since it picks up its meaning from the context of the conversation. Whether “must” says something about someone’s knowledge, or about some set of rules to be followed, depends on the content of B. And if all this is right, it means that the structures of modal phrases — at a minimum — look something like this:
In reality, a bit more needs to be said about this, since a modal base by itself (as we’ve been thinking of it) can’t completely determine the meaning of the sentence. That’s because all the context can really provide is a general description of what’s being talked about — like whether what’s being discussed includes beliefs, rules, goals, abilities, et cetera. But, it can’t take the extra step of supplyingthose beliefs or rules or goals. To get a sense of why this makes a difference, take a look at the following sentence.
(5) I must report to the Colonel.
Imagine that this sentence is said by someone who mistakenly believes that the Colonel asked to see them. In this case, unbeknownst to the speaker, the sentence is false. And the reasonit’s false is because of what the actual requirements are, and not simply what the speaker might suppose they are. So, whether or not this kind of sentence ends up true or false depends on the way the world actually is, and not the way the speaker thinksit is. In other words, speakers can be uninformed about the content of the modal base, in a way that can’t be handled by context alone; that is, they can be mistaken about what the relevant rules or beliefs really consist of. And all of this means that the modal base must really be more like a function that’s meant to take some world as its input (the world in which the sentence is spoken), and then produce a set of worlds out of that, for the modal verb to work with — one that accurately captures whatever’s being talked about.
So, a more complete picture of what the internal structure of a modal phrase looks like is this:
What we see here is a function (sometimes called an accessibility relation) combining with a special kind of world pronoun. This relation R is what’s actually provided by the context of the conversation; it’s what determines the overall flavour. That w* symbol is what does the job of filling in the content of whatever’s being talked about, by providing the full set of rules or abilities under discussion. And it’s together that they determine the modal base — the set of worlds that modals like “must” or “may” go on to compare with the set of worlds described by the rest of the sentence. This way, we fully account for the fact that the truth of modal sentences depends not just on the context of the conversation, but on the way the world is.
As a final point, it’s worth mentioning that no matter which kind of structure we choose to represent modal sentences, none of them ever quite match up with how the sentence is actually pronounced. That is, the Logical Form of the sentence (how it’s interpreted), at least in these cases, is reliably different from its Phonetic Form (how it’s said). In fact, as it’s turned out, the idea that there are mismatches between how sentences are spoken and what they mean has played a big role in modern syntactic theory — one we’ll continue to talk about in the future!
