As the previous chapter showed, Aristotle fixed the seat of truth not in the noun or the verb, but in the sentence joining them. Roughly two thousand years later, a small book written outside Paris takes that insight somewhere Aristotle never intended.
“To speak is to explain one’s thoughts”
In 1660, the theologian Antoine Arnauld and the grammar teacher Claude Lancelot published, anonymously, the Grammaire générale et raisonnée. It opens like this:
Grammar is the art of speaking. To speak is to explain one’s thoughts by signs that men invented for this purpose.
(Japanese and English renderings of quotations throughout are ToL’s own.) “Signs that men invented” — Aristotle’s axiom (language works by convention) carried forward, intact. But Port-Royal doesn’t stop there. If signs were “invented,” what were they invented for? The answer: to explain thought. And if so, the rules of grammar shouldn’t be an arbitrary pile of usage — they should be derivable from the very structure of thought. That’s the book’s wager.
What “is” really is — the act of judging
Aristotle saw, in the “is” linking subject and predicate, the condition under which truth becomes possible (previous chapter). Port-Royal rereads that observation in the vocabulary of psychology. The mind, they argue, has three operations — conceiving (a bare glance at something), judging (asserting that what we conceive is, or is not, thus), and reasoning (linking judgments together). A sentence’s subject and predicate are the trace of “conceiving”; the copula “is” that joins them is the linguistic footprint of “judging” itself (article 052).
For Aristotle, “is” was the condition for truth to have a place to live. For Port-Royal, “is” is the footprint left in language every time the mind performs the act of judging. From pointing at where truth resides, to explaining why it resides there — Aristotle’s observation gets a reason.
From parts of speech to hidden sentences
From this idea, the book rederives nearly all of grammar. The difference between a noun and an adjective is the difference between conceiving something as a substance and conceiving it as a mode (article 051). The verb’s essence is neither tense nor person but “asserting” — carrying the act of judgment itself (article 052). And a complex sentence with a relative clause is analyzed as several judgments folded into one — “the invisible God created the world” turns out to fold together two hidden judgments, “God is invisible” and “God created the world” (article 053).
Every part of grammar reduces to one of the mind’s three operations — this is what “general and rational grammar” means. The differences between individual languages (French, Latin, Arabic…) are, on this view, just different clothing draped over the same shared skeleton.
The wager’s fate — reread three centuries later
This wager didn’t sail on unopposed. In the eighteenth century it spawned the “general grammar” movement and shaped European language teaching for nearly 150 years. But in the nineteenth century, historical and comparative linguistics, prizing empirical evidence, dismissed it as armchair rationalism.
The turning point came in 1966, when Chomsky, in Cartesian Linguistics, named Port-Royal an ancestor of generative grammar. The “hidden sentence” analysis, he argued, anticipates deep and surface structure; the idea that the mind’s structure determines grammar’s structure is the very core of generative grammar. Historians have pushed back hard on this reading, though — Port-Royal’s “depth,” they argue, owes less to Cartesian psychology than to medieval scholastic logic (itself a descendant of Aristotle’s own theory of the proposition). Whichever reading one takes, what Port-Royal actually asked was never “what are this language’s rules?” but “why does language take this shape at all?” — and its answer was always the same: because thought takes this shape.
This wager — the form of grammar mirrors the form of the mind — splits, from here, into two paths. One treats this “mind” as innate, given prior to any experience (the path Chomsky walks in Chapter 6). The other stops short of that and asks instead: if the mind works the same way everywhere, why does the very same mental operation surface as such wildly different grammars in different languages? In the nineteenth century, a Prussian diplomat and linguist named Wilhelm von Humboldt took that second question on directly.