A more intimate scale of distant reading.

How big, exactly, does a collection of literary texts have to be before it makes sense to say we’re doing “distant reading”?

It’s a question people often ask, and a question that distant readers often wriggle out of answering, for good reason. The answer is not determined by the technical limits of any algorithm. It depends, rather, on the size of the blind spots in our knowledge of the literary past — and it’s part of the definition of a blind spot that we don’t already know how big it is. How far do you have to back up before you start seeing patterns that were invisible at your ordinary scale of reading? That’s how big your collection needs to be.

But from watching trends over the last couple of years, I am beginning to get the sense that the threshold for distant reading is turning out to be a bit lower than many people are currently assuming (and lower than I assumed myself in the past). To cut to the chase: it’s probably dozens or scores of books, rather than thousands.

I think there are several reasons why we all got a different impression. One is that Franco Moretti originally advertised distant reading as a continuation of 1990s canon-expansion: the whole point, presumably, was to get beyond the canon and recover a vast “slaughterhouse of literature.” That’s still one part of the project — and it leads to a lot of debate about the difficulty of recovering that slaughterhouse. But sixteen years later, it is becoming clear that new methods also allow us to do a whole lot of things that weren’t envisioned in Moretti’s original manifesto. Even if we restricted our collections to explicitly canonical works, we would still be able to tease out trends that are too long, or family resemblances that are too loose, to be described well in existing histories.

The size of the collection required depends on the question you’re posing. Unsupervised algorithms, like those used for topic modeling, are easy to package as tools: just pour in the books, and out come some topics. But since they’re not designed to answer specific questions, these approaches tend to be most useful for exploratory problems, at large scales of inquiry. (One recent project by Emily Barry, for instance, uses 22,000 Supreme Court cases.)

By contrast, a lot of recent work in distant reading has used supervised models to zero in on narrowly specified historical questions about genre or form. This approach can tell you things you didn’t already know at a smaller scale of inquiry. In “Literary Pattern Recognition,” Hoyt Long and Richard So start by gathering 400 poems in the haiku tradition. In a recent essay on genre I talk about several hundred works of detective fiction, but also ten hardboiled detective novels, and seven Newgate novels.



Predictive accuracy for several genres of roughly generational size, plotted relative to a curve that indicates accuracy for a random sample of detective fiction drawn from the whole period 1829-1989. The shaded ribbon covers 90% of models for a given number of examples.

Admittedly, seven is on the low side. I wouldn’t put a lot of faith in any individual dot above. But I do think we can learn something by looking at five subgenres that each contain 7-21 volumes. (In the graph above we learn, for instance, that focused “generational” genres aren’t lexically more coherent than a sample drawn from the whole 160 years of detective fiction — because the longer tradition is remarkably coherent, and pretty easy to recognize, even when you downsample it to ten or twenty volumes.)

I’d like to pitch this reduction of scale as encouraging news. Grad students and assistant professors don’t have to build million-volume collections before they can start exploring new methods. And literary scholars can practice distant reading without feeling they need to buy into any cyclopean ethic of “big data.” (I’m not sure that ethic exists, except as a vaguely-sketched straw man. But if it did exist, you wouldn’t need to buy into it.)

Computational methods themselves won’t even be necessary for all of this work. For some questions, standard social-scientific content analysis (aka reading texts and characterizing them according to an agreed-upon scheme) is a better way to proceed. In fact, if you look back at “The Slaughterhouse of Literature,” that’s what Moretti did with “about twenty” detective stories (212). Shawna Ross recently did something similar, looking at the representation of women’s scholarship at MLA#16 by reading and characterizing 792 tweets.

Humanists still have a lot to learn about social-scientific methods, as Tanya Clement has recently pointed out. (Inter-rater reliability, anyone?) And I think content analysis will run into some limits as we stretch the timelines of our studies: as you try to cover centuries of social change, it gets hard to frame a predefined coding scheme that’s appropriate for everything on the timeline. Computational models have some advantages at that scale, because they can be relatively flexible. Plus, we actually do want to reach beyond the canon.

But my point is simply that “distant reading” doesn’t prescribe a single scale of analysis. There’s a smooth ramp that leads from describing seven books, to characterizing a score or so (still by hand, but in a more systematic way), to statistical reflection on the uncertainty and variation in your evidence, to text mining and computational modeling (which might cover seven books or seven hundred). Proceed only as far as you find useful for a given question.

Emerging conversations between literary history and sociology.

As Jim English remarked in 2010, literary scholars have tended to use sociology “for its conclusions rather than its methods.” We might borrow a term like “habitus” from Bourdieu, but we weren’t interested in borrowing correspondence analysis. If we wanted to talk about methodology with social scientists at all, we were more likely to go to the linguists. (A connection to linguistics in fact almost defined “humanities computing.”)

But a different conversation seems to have emerged recently. A special issue of Poetics on topic models in 2013 was one early sign of methodological conversation between sociology and literary study. This year, Ben Merriman’s sociological review of books by Moretti and Jockers was followed by comments from Andrew Goldstone and Tressie McMillan Cottom, and then by a special issue of Cultural Sociology and by Goldstone’s response to Gisèle Sapiro. Most recently a special issue of Big Data and Society (table of contents), organized by sociologists, included several articles on literary history and/or literary theory.

What’s going on here?

Conveniently, several articles in Big Data and Society are trying to explain the reasons for growing methodological overlap between these disciplines. I think it’s interesting that the sociologists and literary scholars involved are telling largely the same story (though viewing it, perhaps, from opposite sides of a mirror).

First, the perspective of social scientists. In “Toward a computational hermeneutics,” John W. Mohr, Robin Wagner-Pacifici, and Ronald L. Breiger (who collectively edited this special issue of BDS) suggest that computational methods are facilitating a convergence between the social-scientific tradition of “content analysis” and kinds of close reading that have typically been more central to the humanities.

Close reading? Well, yes, relative to what was previously possible at scale. Content analysis was originally restricted to predefined keywords and phrases that captured the “manifest meaning of a textual corpus” (2). Other kinds of meaning, implicit in “complexities of phrasing” or “rhetorical forms,” had to be discarded to make text usable as data. But according to the authors, computational approaches to text analysis “give us the ability to instead consider a textual corpus in its full hermeneutic complexity,” going beyond the level of interpretation Kenneth Burke called “semantic” to one he considered “poetic” (3-4). This may be interpretation on a larger scale than literary scholars are accustomed to, but from the social-scientific side of the border, it looks like a move in our direction.

JariSchroderus, "Through the Looking Glass," 2006, CC BY-NC-ND 2.0.

Jari Schroderus, “Through the Looking Glass,” 2006, CC BY-NC-ND 2.0.

The essay I contributed to BDS tells a mirror image of this story. I think twentieth-century literary scholars were largely right to ignore quantitative methods. The problems that interested us weren’t easy to represent, for exactly the reason Mohr, Wagner-Pacifici, and Breiger note: the latent complexities of a text had to be discarded in order to treat it as structured data.

But that’s changing. We can pour loosely structured qualitative data into statistical models these days, and that advance basically blurs the boundary we have taken for granted between the quantitative social sciences and humanities. We can create statistical models now where loosely structured texts sit on one side of an equals sign, and evidence about social identity, prestige, or power sits on the other side.

For me, the point of that sort of model is to get beyond one of the frustrating limitations of “humanities computing,” which was that it tended to stall out at the level of linguistic detail. Before we could pose questions about literary form or social conflict, we believed we had to first agree on a stopword list, and a set of features, and a coding scheme, and … in short, if social questions can only be addressed after you solve all the linguistic ones, you never get to any social questions.

But (as I explain at more length in the essay) new approaches to statistical modeling are less finicky about linguistic detail than they used to be. Instead of fretting endlessly about feature selection and xml tags, we can move on to the social questions we want to pose — questions about literary prestige, or genre, or class, or race, or gender. Text can become to some extent a space where we trace social boundaries and study the relations between them.

In short, the long-standing (and still valuable) connection between digital literary scholarship and linguistics can finally be complemented by equally strong connections to other social sciences. I think those connections are going to have fruitful implications, beginning to become visible in this issue of Big Data and Society, and (just over the horizon) in work in progress sponsored by groups like NovelTM and the Chicago Text Lab.

A final question raised by this interdisciplinary conversation involves the notion of big data foregrounded in the journal title. For social scientists, “big data” has a fairly clear meaning — which has less to do with scale, really, than with new ways of gathering data without surveys. But of course surveys were never central to literary study, and it may be no accident that few of the literary scholars involved in this issue of BDS are stressing the bigness of big data. We’ve got terabytes of literature in digital libraries, and we’re using them. But we’re not necessarily making a fuss about “bigness” as such.

Rachel Buurma’s essay on topic-modeling Trollope’s Barsetshire novels explicitly makes a case for the value of topic-modeling at an intermediate scale — while, by the way, arguing persuasively that a topic model is best understood as an “uncanny, shifting, temporary index,” or “counter-factual map” (4). In my essay I discuss a collection of 720 books. That may sound biggish relative to what literary scholars ordinarily do, but it’s explicitly a sample rather than an attempt at coverage, and I argue against calling it big data.

There are a bunch of reasons for that. I’ve argued in the past that the term doesn’t have a clear meaning for humanists. But my stronger objection is that it distracts readers from more interesting things. It allows us to imagine that recent changes are just being driven by faster computers or bigger disks — and obscures underlying philosophical developments that would fascinate humanists if we knew about them.

I believe the advances that matter for humanists have depended less on sheer scale than on new ideas about what it means to model evidence (i.e., learn from it, generalize from it). Machine learning honestly is founded on a theory of learning, and it’s kind of tragic that humanists are understanding something that interesting as a purely technical phenomenon called “big data.” I’m not going to try to explain statistical theories of learning in a short blog post, but in my essay I do at least gesture at a classic discussion by Leo Breiman. Some of my observations overlap with an essay in this same issue of BDS by Paul DiMaggio, who is likewise interested in the epistemological premises involved in machine learning.

How to find English-language fiction, poetry, and drama in HathiTrust.

Although methods of analysis are more fun to discuss, the most challenging part of distant reading may still be locating the texts in the first place [1].

In principle, millions of books are available in digital libraries. But literary historians need collections organized by genre, and locating the fiction or poetry in a digital library is not as simple as it sounds. Older books don’t necessarily have genre information attached. (In HathiTrust, less than 40% of English-language fiction published before 1923 is tagged “fiction” in the appropriate MARC control field.)

Volume-level information wouldn’t be enough to guide machine reading in any case, because genres are mixed up inside volumes. For instance Hoyt Long, Richard So, and I recently published an article in Slate arguing (among other things) that references to specific amounts of money become steadily more common in fiction from 1825 to 1950.

Frequency of reference to "specific amounts" of money in 7,700 English-language works of fiction. Graphics from Wickham, ggplot2 [2].

Frequency of reference to “specific amounts” of money in 7,700 English-language works of fiction. Graphics here and throughout from Wickham, ggplot2 [2].

But Google’s “English Fiction” collection tells a very different story. The frequencies of many symbols that appear in prices (dollar signs, sixpence) skyrocket in the late nineteenth century, and then drop back by the early twentieth.

Frequencies of "$" and "6d" in Google's "English Fiction" collection, 1800-1950.

Frequencies of “$” and “6d” in Google’s “English Fiction” collection, 1800-1950.

On the other hand, several other words or symbols that tend to appear in advertisements for books follow a suspiciously similar trajectory.

Frequencies of "$", "8vo" (octavo) and "cloth" in Google's "English Fiction" collection, 1800-1950.

Frequencies of “$”, “8vo” (octavo) and “cloth” in Google’s “English Fiction” collection, 1800-1950.

What we see in Google’s “Fiction” collection is something that happens in volumes of fiction, but not exactly in the genre of fiction — the rise and fall of publishers’ catalogs in the backs of books [3]. Individually, these two- or three-page lists of titles for sale may not look like significant noise, but because they often mention prices, and are distributed unevenly across the timeline, they add up to a significant potential pitfall for anyone interested in the role of money in fiction.

I don’t say this to criticize the team behind the Ngram Viewer. Genre wasn’t central to their goals; they provided a rough “fiction” collection merely as a cherry on top of a massively successful public-humanities project. My point is just that genres fail to line up with volume boundaries in ways that can really matter for the questions scholars want to pose. (In fact, fiction may be the genre that comes closest to lining up with volume boundaries: drama and poetry often appear mixed in The Collected Poems and Plays of So-and-So, With a Prose Life of the Author.)

You can solve this problem by selecting works manually, or by borrowing proprietary collections from a vendor. Those are both good, practical solutions, especially up to (say) 1900. But because they rely on received bibliographies, they may not entirely fulfill the promises we’ve been making about dredging the depths of “the great unread,” boldly going where no one has gone before, etc [4]. Over the past two years, with support from the ACLS and NEH, I’ve been trying to develop another alternative — a way of starting with a whole library, and dividing it by genre at the page level, using machine learning.

In researching the Slate article, we relied on that automatic mapping of genre to select pages of fiction from HathiTrust. It helped us avoid conflating advertisements with fiction, and I hope other scholars will also find that it reduces the labor involved in creating large, genre-specific collections. The point of this blog post is to announce the release of a first version of the map we used (covering 854,476 English-language books in HathiTrust 1700-1922).

The whole dataset is available on Figshare, where it has a DOI and is citable as a publication. An interim report is also available; it addresses theoretical questions about genre, as well as questions about methods and data format. And the code we used for the project is available on Github.

For in-depth answers to questions, please consult the interim project report. It’s 47 pages long; it actually explains the project; this blog post doesn’t. But here are a few quick FAQs just so you can decide whether to read further.

“What categories did you try to separate?”

We identify pages as paratext (front matter, back matter, ads), prose nonfiction, poetry (narrative and lyric are grouped together), drama (including verse drama), or prose fiction. The report discusses the rationale for these choices, but other choices would be possible.

“How accurate is this map?”

Since genres are social institutions, questions about accuracy are relative to human dissensus. Our pairs of human readers agreed about the five categories just mentioned for 94.5% of the pages they tagged [5]. Relying on two-out-of-three voting (among other things), we boiled those varying opinions down to a human consensus, and our model agreed with the consensus 93.6% of the time. So this map is nearly as accurate as we might expect crowdsourcing to be. But it covers 276 million pages. For full details, see the confusion matrices in the report. Also, note that we provide ways of adjusting the tradeoff between recall and precision to fit a researcher’s top priority — which could be catching everything that might belong in a genre, or filtering out everything that doesn’t belong. We provide filtered collections of drama, fiction, and poetry for scholars who want to work with datasets that are 97-98% precise.

“You just wrote a blog post admitting that even simple generic boundaries like fiction/nonfiction are blurry and contested. So how can we pretend to stabilize a single map of genre?”

The short answer: we can’t. I don’t expect the genre predictions in this dataset to be more than one resource among many. We’ve also designed this dataset to have a certain amount of flexibility. There are confidence metrics associated with each volume, and users can define their collection of, say, poetry more broadly or narrowly by adjusting the confidence thresholds for inclusion. So even this dataset is not really a single map.

“What about divisions below the page level?”

With the exception of divisions between running headers and body text, we don’t address them. There are certainly a wide range of divisions below the page level that can matter, but we didn’t feel there was much to be gained by trying to solve all those problems at the same time as page-level mapping. In many cases, divisions below the page level are logically a subsequent step.

“How would I actually use this map to find stuff?”

There are three different ways — see “How to use this data?” in the interim report. If you’re working with HathiTrust Research Center, you could use this data to define a workset in their portal. Alternatively, if your research question can be answered with word frequencies, you could download public page-level features from HTRC and align them with our genre predictions on your own machine to produce a dataset of word counts from “only pages that have a 97% probability of being prose fiction,” or what have you. (HTRC hasn’t released feature counts for all the volumes we mapped yet, but they’re about to.) You can also align our predictions directly with HathiTrust zip files, if you have those. The pagealigner module in the utilities subfolder of our Github repo is intended as a handy shortcut for people who use Python; it will work both with HT zip files and HTRC feature files, aligning them with our genre predictions and returning a list of pages zipped with genre codes.

Is this sort of collection really what I need for my project?

Maybe not. There are a lot of books in HathiTrust. But as I admitted in my last post, a medium-sized collection based on bibliographies may be a better starting point for most scholars. Library-based collections include things like reprints, works in translation, juvenile fiction, and so on, that could be viewed as giving a fuller picture of literary culture … or could be viewed as messy complicating factors. I don’t mean to advocate for a library-based approach; I’m just trying to expand the range of alternatives we have available.

“What if I want to find fiction in French books between 1900 and 1970?”

Although we’ve made our code available as a resource, we definitely don’t want to represent it as a “tool” that could simply be pointed at other collections to do the same kind of genre mapping. Much of the work involved in this process is domain-specific (for instance, you have to develop page-level training data in a particular language and period). So this is better characterized as a method than a tool, and the report is probably more important than the repo. I plan to continue expanding the English-language map into the twentieth century (algorithmic mapping of genre may in fact be especially necessary for distant reading behind the veil of copyright). But I don’t personally have plans to expand this map to other languages; I hope someone else will take up that task.

As a reward for reading this far, here’s a visualization of the relative sizes of genres across time, represented as a percentage of pages in the English-language portion of HathiTrust.

The relative sizes of different genres, represented as a percentage of pages in the English-language portion of HathiTrust. 854,476 volumes are covered. Nonfiction, front matter, and back matter aren't represented here. Results have been smoothed with a five-year moving average.

The relative sizes of different genres, represented as a percentage of pages in the English-language portion of HathiTrust. 854,476 volumes are covered. Nonfiction, front matter, and back matter aren’t represented here. Results have been smoothed with a five-year moving average. Click through to enlarge.

The image is discussed at more length in the interim progress report.


The blog post above often slips awkwardly into first-person plural, because I’m describing a project that involved a lot of people. Parts of the code involved were written by Michael L. Black and Boris Capitanu. The code also draws on machine learning libraries in Weka and Scikit-Learn [6, 7]. Shawn Ballard organized the process of gathering training data, assisted by Jonathan Cheng, Nicole Moore, Clara Mount, and Lea Potter. The project also depended on collaboration and conversation with a wide range of people at HathiTrust Digital Library, HathiTrust Research Center, and the University of Illinois Library, including but not limited to Loretta Auvil, Timothy Cole, Stephen Downie, Colleen Fallaw, Harriett Green, Myung-Ja Han, Jacob Jett, and Jeremy York. Jana Diesner and David Bamman offered useful advice about machine learning. Essential material support was provided by a Digital Humanities Start-Up Grant from the National Endowment for the Humanities and a Digital Innovation Fellowship from the American Council of Learned Societies. None of these people or agencies should be held responsible for mistakes.


[1] Perhaps it goes without saying, since the phrase has now lost its quotation marks, but “distant reading” is Franco Moretti, “Conjectures on World Literature,” New Left Review 1 (2000).

[2] Hadley Wickham, ggplot2: Elegant Graphics for Data Analysis. http: //had.co.nz/ggplot2/book. Springer New York, 2009.

[3] Having mapped advertisements in volumes of fiction, I’m pretty certain that they’re responsible for the spike in dollar signs in Google’s “English Fiction” collection. The collection I mapped overlaps heavily with Google Books, and the number of pages of ads in fiction volumes tracks very closely with the frequency of dollars signs, “8vo,” and so on.

Percentage of pages in mostly-fiction volumes that are ads. Based on a filtered collection of 102,349 mostly-fiction volumes selected from a larger group of 854,476 volumes 1700-1922.

Percentage of pages in mostly-fiction volumes that are ads. Based on a filtered collection of 102,349 mostly-fiction volumes selected from a larger group of 854,476 volumes 1700-1922. Five-year moving average.

[4] “The great unread” comes from Margaret Cohen, The Sentimental Education of the Novel (Princeton NJ: Princeton University Press, 1999), 23.

[5] See the interim report (subsection, “Evaluating Confusion Matrices”) for a fuller description; it gets complicated, because we actually assessed accuracy in terms of the number of words misclassified, although the classification was taking place at a page level.

[6] F. Pedregosa, G. Varoquaux, A. Gramfort, V. Michel, B. Thirion, O. Grisel, M. Blondel, P. Prettenhofer, R. Weiss, V. Dubourg, J. Vanderplas, A. Passos, D. Cournapeau, M. Brucher, M. Perrot, and E. Duchesnay. Scikit-learn: Machine learning in Python. Journal of Machine Learning Research, 12:2825–2830, 2011.

[7] Mark Hall, Eibe Frank, Geoffrey Holmes, Bernhard Pfahringer, Peter Reutemann, and Ian H. Witten. The WEKA data mining software: An update. SIGKDD Explorations, 11(1), 2009.

Measurement and modeling.

If the Internet is good for anything, it’s good for speeding up the Ent-like conversation between articles, to make that rumble more perceptible by human ears. I thought I might help the process along by summarizing the Stanford Literary Lab’s latest pamphlet — a single-authored piece by Franco Moretti, “‘Operationalizing’: or the function of measurement in modern literary theory.”

One of the many strengths of Moretti’s writing is a willingness to dramatize his own learning process. This pamphlet situates itself as a twist in the ongoing evolution of “computational criticism,” a turn from literary history to literary theory.

Measurement as a challenge to literary theory, one could say, echoing a famous essay by Hans Robert Jauss. This is not what I expected from the encounter of computation and criticism; I assumed, like so many others, that the new approach would change the history, rather than the theory of literature ….

Measurement challenges literary theory because it asks us to “operationalize” existing critical concepts — to say, for instance, exactly how we know that one character occupies more “space” in a work than another. Are we talking simply about the number of words they speak? or perhaps about their degree of interaction with other characters?

Moretti uses Alex Woloch’s concept of “character-space” as a specific example of what it means to operationalize a concept, but he’s more interested in exploring the broader epistemological question of what we gain by operationalizing things. When literary scholars discuss quantification, we often tacitly assume that measurement itself is on trial. We ask ourselves whether measurement is an adequate proxy for our existing critical concepts. Can mere numbers capture the ineffable nuances we assume they possess? Here, Moretti flips that assumption and suggests that measurement may have something to teach us about our concepts — as we’re forced to make them concrete, we may discover that we understood them imperfectly. At the end of the article, he suggests for instance (after begging divine forgiveness) that Hegel may have been wrong about “tragic collision.”

I think Moretti is frankly right about the broad question this pamphlet opens. If we engage quantitative methods seriously, they’re not going to remain confined to empirical observations about the history of predefined critical concepts. Quantification is going to push back against the concepts themselves, and spill over into theoretical debate. I warned y’all back in August that literary theory was “about to get interesting again,” and this is very much what I had in mind.

At this point in a scholarly review, the standard procedure is to point out that a work nevertheless possesses “oversights.” (Insight, meet blindness!) But I don’t think Moretti is actually blind to any of the reflections I add below. We have differences of rhetorical emphasis, which is not the same thing.

For instance, Moretti does acknowledge that trying to operationalize concepts could cause them to dissolve in our hands, if they’re revealed as unstable or badly framed (see his response to Bridgman on pp. 9-10). But he chooses to focus on a case where this doesn’t happen. Hegel’s concept of “tragic collision” holds together, on his account; we just learn something new about it.

In most of the quantitative projects I’m pursuing, this has not been my experience. For instance, in developing statistical models of genre, the first thing I learned was that critics use the word genre to cover a range of different kinds of categories, with different degrees of coherence and historical volatility. Instead of coming up with a single way to operationalize genre, I’m going to end up producing several different mapping strategies that address patterns on different scales.

Something similar might be true even about a concept like “character.” In Vladimir Propp’s Morphology of the Folktale, for instance, characters are reduced to plot functions. Characters don’t have to be people or have agency: when the hero plucks a magic apple from a tree, the tree itself occupies the role of “donor.” On Propp’s account, it would be meaningless to represent a tale like “Le Petit Chaperon Rouge” as a social network. Our desire to imagine narrative as a network of interactions between imagined “people” (wolf ⇌ grandmother) presupposes a separation between nodes and edges that makes no sense for Propp. But this doesn’t necessarily mean that Moretti is wrong to represent Hamlet as a social network: Hamlet is not Red Riding Hood, and tragic drama arguably envisions character in a different way. In short, one of the things we might learn by operationalizing the term “character” is that the term has genuinely different meanings in different genres, obscured for us by the mere continuity of a verbal sign. [I should probably be citing Tzvetan Todorov here, The Poetics of Prose, chapter 5.]

Illustration from "Learning Latent Personas of Film Characters," Bamman et. al.

Illustration from “Learning Latent Personas of Film Characters,” Bamman et. al.

Another place where I’d mark a difference of emphasis from Moretti involves the tension, named in my title, between “measurement” and “modeling.” Moretti acknowledges that there are people (like Graham Sack) who assume that character-space can’t be measured directly, and therefore look for “proxy variables.” But concepts that can’t be directly measured raise a set of issues that are quite a bit more challenging than the concept of a “proxy” might imply. Sack is actually trying to build models that postulate relations between measurements. Digital humanists are probably most familiar with modeling in the guise of topic modeling, a way of mapping discourse by postulating latent variables called “topics” that can’t be directly observed. But modeling is a flexible heuristic that could be used in a lot of different ways.

The illustration on the right is a probabilistic graphical model drawn from a paper on the “Latent Personas of Film Characters” by Bamman, O’Connor, and Smith. The model represents a network of conditional relationships between variables. Some of those variables can be observed (like words in a plot summary w and external information about the film being summarized md), but some have to be inferred, like recurring character types (p) that are hypothesized to structure film narrative.

Having empirically observed the effects of illustrations like this on literary scholars, I can report that they produce deep, Lovecraftian horror. Nothing looks bristlier and more positivist than plate notation.

But I think this is a tragic miscommunication produced by language barriers that both sides need to overcome. The point of model-building is actually to address the reservations and nuances that humanists correctly want to interject whenever the concept of “measurement” comes up. Many concepts can’t be directly measured. In fact, many of our critical concepts are only provisional hypotheses about unseen categories that might (or might not) structure literary discourse. Before we can attempt to operationalize those categories, we need to make underlying assumptions explicit. That’s precisely what a model allows us to do.

It’s probably going to turn out that many things are simply beyond our power to model: ideology and social change, for instance, are very important and not at all easy to model quantitatively. But I think Moretti is absolutely right that literary scholars have a lot to gain by trying to operationalize basic concepts like genre and character. In some cases we may be able to do that by direct measurement; in other cases it may require model-building. In some cases we may come away from the enterprise with a better definition of existing concepts; in other cases those concepts may dissolve in our hands, revealed as more unstable than even poststructuralists imagined. The only thing I would say confidently about this project is that it promises to be interesting.

Interesting times for literary theory.

A couple of weeks ago, after reading abstracts from DH2013, I said that the take-away for me was that “literary theory is about to get interesting again” – subtweeting the course of history in a way that I guess I ought to explain.

A 1915 book by Chicago's "Professor of Literary Theory."

A 1915 book by Chicago’s “Professor of Literary Theory.”

In the twentieth century, “literary theory” was often a name for the sparks that flew when literary scholars pushed back against challenges from social science. Theory became part of the academic study of literature around 1900, when the comparative study of folklore seemed to reveal coherent patterns in national literatures that scholars had previously treated separately. Schools like the University of Chicago hired “Professors of Literary Theory” to explore the controversial possibility of generalization.* Later in the century, structural linguistics posed an analogous challenge, claiming to glimpse an organizing pattern in language that literary scholars sought to appropriate and/or deconstruct. Once again, sparks flew.

I think literary scholars are about to face a similarly productive challenge from the discipline of machine learning — a subfield of computer science that studies learning as a problem of generalization from limited evidence. The discipline has made practical contributions to commercial IT, but it’s an epistemological method founded on statistics more than it is a collection of specific tools, and it tends to be intellectually adventurous: lately, researchers are trying to model concepts like “character” (pdf) and “gender,” citing Judith Butler in the process (pdf).

At DH2013 and elsewhere, I see promising signs that literary scholars are gearing up to reply. In some cases we’re applying methods of machine learning to new problems; in some cases we’re borrowing the discipline’s broader underlying concepts (e.g. the notion of a “generative model”); in some cases we’re grappling skeptically with its premises. (There are also, of course, significant collaborations between scholars in both fields.)

This could be the beginning of a beautiful friendship. I realize a marriage between machine learning and literary theory sounds implausible: people who enjoy one of these things are pretty likely to believe the other is fraudulent and evil.** But after reading through a couple of ML textbooks,*** I’m convinced that literary theorists and computer scientists wrestle with similar problems, in ways that are at least loosely congruent. Neither field is interested in the mere accumulation of data; both are interested in understanding the way we think and the kinds of patterns we recognize in language. Both fields are interested in problems that lack a single correct answer, and have to be mapped in shades of gray (ML calls these shades “probability”). Both disciplines are preoccupied with the danger of overgeneralization (literary theorists call this “essentialism”; computer scientists call it “overfitting”). Instead of saying “every interpretation is based on some previous assumption,” computer scientists say “every model depends on some prior probability,” but there’s really a similar kind of self-scrutiny involved.

It’s already clear that machine learning algorithms (like topic modeling) can be useful tools for humanists. But I think I glimpse an even more productive conversation taking shape, where instead of borrowing fully-formed “tools,” humanists borrow the statistical language of ML to think rigorously about different kinds of uncertainty, and return the favor by exposing the discipline to boundary cases that challenge its methods.

Won’t quantitative models of phenomena like plot and genre simplify literature by flattening out individual variation? Sure. But the same thing could be said about Freud and Lévi-Strauss. When scientists (or social scientists) write about literature they tend to produce models that literary scholars find overly general. Which doesn’t prevent those models from advancing theoretical reflection on literature! I think humanists, conversely, can warn scientists away from blind alleys by reminding them that concepts like “gender” and “genre” are historically unstable. If you assume words like that have a single meaning, you’re already overfitting your model.

Of course, if literary theory and computer science do have a conversation, a large part of the conversation is going to be a meta-debate about what the conversation can or can’t achieve. And perhaps, in the end, there will be limits to the congruence of these disciplines. Alan Liu’s recent essay in PMLA pushes against the notion that learning algorithms can be analogous to human interpretation, suggesting that statistical models become meaningful only through the inclusion of human “seed concepts.” I’m not certain how deep this particular disagreement goes, because I think machine learning researchers would actually agree with Liu that statistical modeling never starts from a tabula rasa. Even “unsupervised” algorithms have priors. More importantly, human beings have to decide what kind of model is appropriate for a given problem: machine learning aims to extend our leverage over large volumes of data, not to take us out of the hermeneutic circle altogether.

But as Liu’s essay demonstrates, this is going to be a lively, deeply theorized conversation even where it turns out that literary theory and computer science have fundamental differences. These disciplines are clearly thinking about similar questions: Liu is right to recognize that unsupervised learning, for instance, raises hermeneutic questions of a kind that are familiar to literary theorists. If our disciplines really approach similar questions in incompatible ways, it will be a matter of some importance to understand why.

0804784469* <plug> For more on “literary theory” in the early twentieth century, see the fourth chapter of Why Literary Periods Mattered: Historical Contrast and the Prestige of English Studies (2013, hot off the press). The book has a lovely cover, but unfortunately has nothing to do with machine learning. </plug>

** This post grows out of a conversation I had with Eleanor Courtemanche, in which I tried to convince her that machine learning doesn’t just reproduce the biases you bring to it.

*** Practically, I usually rely on Data Mining: Practical Machine Learning Tools and Techniques (Ian Witten, Eibe Frank, Mark Hall), but to understand the deeper logic of the field I’ve been reading Machine Learning: A Probabilistic Perspective (Kevin P. Murphy). Literary theorists may appreciate Murphy’s remark that wealth has a long-tailed distribution, “especially in plutocracies such as the USA” (43).

PS later that afternoon: Belatedly realize I didn’t say anything about the most controversial word in my original tweet: “literary theory is about to get interesting again.” I suppose I tacitly distinguish literary theory (which has been a little sleepy lately, imo) from theory-sans-adjective (which has been vigorous, although hard to define). But now I’m getting into a distinction that’s much too slippery for a short blog post.