Some other interesting Ngrams.
* Comparing the occurrences of the phrases "ontological argument", "cosmological argument", and "teleological argument", which are Kant's three labels for pure-reason arguments for God's existence.
* Comparing three different names for design arguments.
* Kant's three Critiques.
* Comparing Hume's two best-known works.
* "Summa Theologiae" vs. "Summa Theologica".
* Given the relative difficulty of accessing the underlying data, the primary usefulness of the viewer seems to be the identifying of rough beginnings and endings of name uses, as well as fads and fashions in labels and classifications. (Rough because nothing registers in the Ngram Viewer unless it has more than forty mentions.) Here is the Ngram for "Bridgewater Treatise" and "Bridgewater Treatises".
* A more interesting example. One often finds the atheistic argument from evil summarized as being the inconsistency of the existence of evil with the combined attributes of omnipotence, omniscience, and omnibenevolence. But this is a little peculiar; everyone who knows anything about it knows that "omnibenevolence" is not an especially traditional label for anything. And, indeed, the Ngram for it shows this quite nicely, and gives us (one more) good reason to demand to know what people mean by the term.
* Here are three nineteenth-century friends and how their names fared in the twentieth century. William Whewell is on a slow, uneven ascent for much of the twentieth century. John Herschel, on the other hand, is plummeting at the beginning of the century, and it is not difficult to see why. In the nineteenth century, John Herschel was one of the most eminent scientists of the day, and the son of one of the most eminent scientists of the generation before; his name was virtually a household word in many parts of the world. Indeed, if you do the Ngram for the three names in the nineteenth century, Herschel's name spikes so high that you can hardly tell what the other names are doing. This was unsustainable; only a very small handful of scientific names are commonly bandied about, while the rest get crowded out by more contemporary names. Herschel's name peaks shortly after his death in 1871, and goes into decline from then on. With Babbage things are different. He starts seeing a substantive rise between 1940 and 1950; the Computer Age does the courtesy of at least mentioning Mr. Analytical Engine. The change is very visible when you look at him alone, although in absolute terms we're still talking a fairly modest rise.
* The Ngram for "aesthetics". We see its first introduction into English (from the German) and increasing use.
* "Gestalt" becomes an English word.
* The word "scientist" spreads out from William Whewell. But note the differences in the American English corpus and the British English corpus. It somewhat confirms what is usually held on other evidence, namely, that despite the British origin, it caught on a bit more quickly in American English due to people like C. S. Peirce.
* "Agnosticism" is advocated as a label by T. H. Huxley and becomes a common word.
* Science fiction becomes a genre.
* Feminist philosophy begins to cohere as a philosophical topic. Ditto with philosophy of sport
. Modal logic becomes a field. People begin to talk about predicate calculus.
* People start talking about a "problem of induction". And also about the problem of evil.
* "natural theology" vs. "philosophy of religion"
* It becomes more common to speak of "parapsychology" rather than "psychical research".
* Kant is translated into English and "categorical imperative" spreads.
* The contrasting fates of "non sequitur" and "petitio principii" as labels for fallacies.
* The twentieth century nearly loses the common term, "moral providence", and "Christian Evidences"
declines as a field of philosophy. Casuistry also declines as a field of philosophy.
* "secularism" becomes a common term, as does "scientism".
* The notion of "artificial intelligence" begins to spread.
* People start talking about determinism (before some time in the last half of the nineteenth century, people talked about the doctrine of Necessity rather than about determinism).
* Higher Criticism.
* Thomism returns to visibility. Catholic Theology of the Body spreads under the influence of John Paul II.
* "the whole shebang" vs. "the whole nine yards"
* WWII makes people notice the importance of airplanes.
* "anarchist" and "communist" and "terrorist"
* Communism vs. Capitalism.
All in all, of course, interpretation of the results always requires knowing things that aren't on the graphs; and the whole thing has a fair number of false positives and false negatives, whatever you do, so precise shapes of curves and lines can't be trusted. But still fun to play with.
* Leo thought up another really good one: sublime, its ascent and descent.
* Here's another one: picturesque.
* And, going off a suggestion by Bruce: moral values, which is very much a phrase for the twentieth century.
* And the slow decline of talk about duty and duties.
* dogmatic theology vs. systematic theology.
* justification by faith alone
* "King James Version" vs. "Authorized Version"
* Fundamentalism becomes a common term.
* Our Father, Paternoster, Lord's Prayer
* "I think therefore I am" vs "cogito ergo sum"
* Pascal's Wager
* paradigm and falsifiability (paradigm so far outstrips falsifiability you can't put them together).
* beautiful people