I’d been planning on posting the final part of my discussion of the exchange of letters between Isaiah Berlin and Karl Popper on liberty and enlightenment, but various commitments have conspired to delay my posting of that discussion until later in the week. But I’d been planning to say a few things about what we can — and mostly can’t — learn about the distinctions Berlin sought to draw by looking at the frequency of usage of the terms he was discussing. So now seems as good (or, as it turns out, as bad) a time as any to say it. Hence, here is a sort of “pre-postscript” to my posts on Berlin and Popper.
Earlier this term I discussed Berlin’s Two Concepts essay in my introductory political thought course and I thought it might be interesting to show the class (most of whom hadn’t heard about Ngram) how patterns in the use of “liberty” and “freedom” have changed over time. The results were more or less what I’d expected: “liberty” crests around 1790 and then begins a slow descent, “freedom” plays the tortoise to liberty’s hare and pulls ahead around 1905.
After constructing the Ngram it struck to me that I ought to push the end date up from Google’s default of 2000 to something closer to the present in order to see if there had been any uptick in uses of “freedom” in the wake of the September 2001 attacks (it certainly seemed as if “freedom” was being invoked quite a bit between 2001-2004, particularly by the man who just got his very own Presidential Library). Surprisingly, nothing seems to happen.
What I hadn’t thought to do at the time was to see if there was any way of seeing whether the nGram could tell us anything about shifts in the invocation of the concepts of positive and negative conceptions of liberty. But an attempt along these lines rather quickly brings us up against the difficulties of trying to pick up changes in the use of concepts by looking at changes in the use of words. For starters, an Ngram for uses of the phrases “positive liberty” and “negative liberty” tells us next to nothing. The reasons for this are easy enough to see: (1) these are technical terms that enjoy rather little usage outside of a specialized literature, so shifts in the frequency of their usage are small moves in a rather small sample and (2) they are terms that tend to be used together, as a way of drawing a distinction in philosophical discussions. As a result, all that such a search will pick up is how many articles are being published in any given year that are invoking the distinction that Isaiah Berlin made famous.
However, Berlin did employ, in passing, the circumlocution “liberty from” as a way of denoting “negative liberty,” a usage that echoes a distinction that Franklin Roosevelt had drawn in his list of the “Four Freedoms” between “freedom from” want and fear and “freedom of” speech and worship. And, much more emphatically, Erich Fromm’s Escape from Freedom (1941) had framed the distinction between “positive” and “negative” freedoms as the distinction between “freedom to” and “freedom from.” I’ve always found this way of explaining Berlin’s distinction more of a hindrance than a help: typically (and, I suspect, rightly) it tends to confuse students. They ask “Isn’t freedom from regulations that forbid something the same thing as freedom to do it?” and I say “Don’t pay attention to that” and point them to the way in which Berlin framed the distinction: negative liberty “is involved in the answer to the question ‘What is the area within which the subject — a person or group of persons — is or should be left to do or be what he wants to do or be, without interference by other persons?'” In contrast, positive liberty, “is involved in the answer to the question ‘What, or who, is the source of control or interference, that can determine someone to do, or be, one thing rather than another?'” But while the conceptual distinction between positive and negative liberty might better be grasped by focusing on the questions that Berlin posed, it is possible that tracking the use of the colloquial distinction between “freedom from” and “freedom to” might pick up something worthwhile.
Let’s start with “freedom from,” “freedom to,” and, for the sake of completeness, “liberty from” and “liberty to” (it turns out that there is no need to worry about the capitalized form of the terms):
At first glance, what we have here seem quite peculiar: the most notable feature is the long decline of “liberty to.” But a moment’s reflection should be enough to remind us that this decline probably tells us more about the fading of the once-prevalent idiom “at liberty to do x” than it does about the distinction between “positive” and “negative” forms of freedom or liberty. The Ngram may also be reminding us of two other things: (1) there is no equivalent idiom “at liberty from x” and (2) there are different idioms in play for talking about “freedom”: namely, “free to” and “free from.”
On one of the more influential early critique of the Two Concepts lecture, the American political theorist Gerold MacCallum argued that instead of seeing disputes over the concept of liberty as involving a struggle between Berlin’s “liberal” notion of “negative liberty” and the “romantic” (and potentially totalitarian) concept of “positive liberty,” we would do better “to regard freedom as always one and the same triadic relation, but recognize that various contending parties disagree with each other in what they understand to be the ranges of the term variables.” [“Negative and Positive Freedom,” The Philosophical Review 76, no. 3 (July 1967): 312]. He proposed that
Whenever the freedom of some agent or agents is in question, it is always freedom from some constraint or restriction on, interference with, or barrier to doing, not doing, becoming, or not becoming something. Such freedom is thus always of something (an agent or agents), from something, to do, not do, become, or not become something; it is a triadic relation. Taking the format “x is (is not) free from (to do, not do, become, not become) z,” x ranges over agents, y ranges over such “preventing conditions” as constraints, restrictions, interferences, and barriers, and z ranges over actions or conditions of character or circumstance. 
MacCallum, it should be stressed, was proposing a conceptual distinction, but he argued that we could use the distinction could clarify how disputes involving freedom might be seen as:
a series of attempts by parties opposing each other on very many issues to capture for their own side the favorable attitudes attaching to the notion of freedom. 
If MacCallum’s conceptual distinction remotely corresponds to the way in which contesting parties talk about freedom, what we would expect to find, at any given moment, is a rough equivalence in uses of “free from,” “free to,” “freedom of” and the corresponding forms of liberty. But (and here I am tempted to add “of course”), we don’t:
This is a really ugly Ngram (and not just because it would profit from a better contrast between its colors), but it may have something to tell us about the folly of trying to use an Ngram to frame a history of this sort of concept (I’d like to think that there are other concepts whose history might be tracked more effectively byNgrams — for instance, “enlightenment”). Here’s what I think I’ve learned from this (I’ll be interested in seeing what others make of it):
- What we’re seeing here is not what a straightforward translation of MacCallum’s conceptual distinction into word usage would have suggested. We do see movement in the different aspects of his “unitary” concept of freedom. While there may well be variation in the ways in which different parties fill out the different parts of his “unitary” notion, what we seem to see here is that, over time, there is a shift in the usage of “freedom of,” “free from,” “free to.”
- I suspect, however, that some of what we are seeing here can best be explained in the migration of certain circumlocutions from various specialized discourses into common usage (and, perhaps, the reverse). For example: “freedom of” sounds, at least to me, like a term that had been at home in legal discourse, but began to spread into other domains during the 1930s (this is the sort of change that Bookworm is tailor-made to pick up).
- Other changes (e.g., the decaying of “freedom of” and the rise of “free of”) might reflect nothing more significant than a preference for the shorter term “free” over the more technical sounding “freedom.”
- Finally, to give MacCallum his due, perhaps we can understand the convergence of “freedom of,” “free to,” “free of,” and “free from” as we near 2000 as evidence that those who are engaged in disputes about “freedom” are busily involved in defining the “freedom of” agents “from” certain impediments “to” do or be something or other.
But, in the end, I’m inclined to think that the exercise in which I’ve been engaged here really doesn’t have much to recommend it.