Tuesday, April 27, 2010

Discussion Arcs

A philosophical discussion arc, as I'll use the term, is a curve displaying how often a topic or author is used as a "keyword" in a philosophical journal article or book abstract (i.e., in the article's or book's title, abstract, or list of key words). By looking at discussion arcs we can see what topics have been hot and what philosophers have been influential.

Let's begin with topical discussion arcs. On the x-axis is publication year, in five-year slices. The y-axis is a ratio: It's the number of articles in the Philosopher's Index containing the keyword, divided by a representative universe of articles, multiplied by 100. The data begin in 1940.

(A ratio is a much more accurate indicator of influence than is raw number, since the number of philosophy articles has increased about twenty-fold since the 1940s. I generated the representative universes, which serve at the denominators, by broad keyword searches, as indicated with each graph.)

Some topics have generated consistent interest over the decades. Dualism is one, as you can see below. The * is a truncation symbol, so this chart tracks any keyword starting with "dualis".

[Representative universe: language + epistemology + mind + metaphysics -- lemmings for short.]

Interest in the leading 17th and 18th century philosophers is also steady across the period (with perhaps Kant gaining discussion and Locke losing discussion):

[Representative universe: Lemmings + ethic* + moral* + polit*, or EMPlemmings for short]

Voguish topics, in contrast, are arc shaped.

Here, for example, is "twin earth" (a thought experiment about what the word "water" would mean in a world virtually identical to ours but with a different chemical formula for water):

[Representative universe: Lemmings]

And here is "ordinary language" (a way of thinking about philosophical issues popular in the middle of the twentieth century):

[Representative universe: Lemmings]

Here's a chart that displays the rise of Nietzsche from the second tier of historical figures into the first tier. (Note Nietzsche's final y-axis numbers are higher than those of Descartes, Locke, or Hume in the chart above.)

[Representative univerise: EMPLemmings]

Twentieth century philosophers also have arcs. Here are five influential philosophers born in the 1910s. Note that discussion of their work tended to peak at about age sixty, with the exception of Donald Davidson:

[Representative universe: Lemmings]

In fact, there's a fairly consistent pattern for the influence of 20th century analytic philosophers, as measured by discussion arc, to peak around age 55-70. The following chart shows average discussion-arc data from 26 prominent 20th century philosophers, with age on the x-axis. I normalized each philosopher's peak influence to 1. I did not truncate the philosophers' discussion arcs at death.

[Representative universe: Lemmings; all included philosophers are Lemmings specialists]

I find it interesting that influence tends to peak at age 55-70, while the age at which philosophers tend to do their most influential work is about 35-40. (Here's a preliminary discussion of that last point; I hope to have fuller data on the matter soon.) I guess it takes time for word to get around!

Update, May 12:

In this more recent post, I (mostly) retract my claim about the age at which the most influential philosophical work tends to be done. Check out this cool chart!


Anonymous said...

Hi Eric,

I have completed my first year studying Philosophy at University College Cork in Ireland. I was intrigued by your graph about the concept of "Twin Earth", as I have never heard about it before. It seems to me that if there was another planet with the same ratio of liquid as there is here water to land; the lack of water would mean the lack to life. Is this the correct way of thinking about it? Or does it mean the twin planet is exactly like ours JUST with the replacement of water to some other liquid?

I dunno... interesting:)

Philip Saunders


Michael said...

I posted a skeptical comment on your old post about when philosophers do their best work, in particular wrt Davidson...

Michael Kremer

Eric Schwitzgebel said...

Philip - check out the link in the post, for a good explanation of Twin Earth.

Michael - see my comment on the other post.

max said...

Hi Eric,
very nice work! As a beginning philosopher the lesson to me would be to write my dissertation on a roughly 55 year old philosopher rather than on a philosopher in his 70s or 80s.
What do you think of this hypothesis: With the internet's possibility of faster exchange of information and ideas yould we expect the peak to move more toward the actual phase of production?

as an aside: twin earth is not "a world virtually identical to ours but with a different chemical formula for water" - the whole point is that there is no water on twin earth. i'm sure you know this, so, funny then, how fluffy our language is.

Eric Schwitzgebel said...

Thanks for the comment, Max. I recommend dissertating on what you're passionate about, using "marketability" as a tie-breaker only in close cases.

You hypothesis about a shortening delay is interesting. I wouldn't be surprised if there is some shortening up in light of faster communication and travel. I don't know if I can get enough data across a range of history to address that, though.

And yes, in my summary of the Twin Earth thought experiment I sacrificed accuracy for brevity.

Philoponus said...

Eric (if I may),

This is very interesting work. The anomalous distributions of Kant, Nietzsche, Wittgenstein and Davidson are phenomena wanting explanation, don't you think?. I'm sure you have good ideas about how to pursue this. I would be fun to take one of these figures and see who all exactly is responsible for his continued strong showing. Several groups of people, I suspect. In the case of Kant, maybe one or two philo depts with strong Kant Studien programmes? Maybe several recent good books on Kant? I don't know what actually will turn up, but I'm sure it would be be interesting inquiry.

Your puzzlement over Kuhn and Popper, as you say, might be resolved by looking at some broad scientific citation indexes, where you'll likely find these names well represented (while other once popular philos of science like Lakatos are ignored). In general, it would be very interesting to look at the extent to which contemporary science has any interest in contemporary philosophy. I think the lingustics people, for example, are still very interested in speech acts and conversational implicatures, although it seem rare these days to find a philo who knows who JL Austin or Grice was.

In any case, Eric, excellent work that I hope gets continued and built on.

Eric Schwitzgebel said...

Thanks, Philoponus! I do hope to develop these ideas further, as you suggest!

KW said...

Just FYI, the real growth industry in Kant scholarship is in his aesthetics and other topics covered in the Third Critique, which may be beyond the scope of what you call "EMPLemmings".

Anonymous said...

hi Eric,
The line for Grice just can't be right. He's had far more influence than Davidson and Chisholm, all told. And his line couldn't be nearly flat. Did you only code for certain philosophy journals, leaving off, for example, numerous central journals in linguistics, psychology, computer science and robots for which his work has been incredibly, and increasingly, influential?
gotta plug the greats... Robin

Eric Schwitzgebel said...

Yes, Robin, this is Philosophers Index only -- so influence outside of philosophy is not being measured. I notice that Grice ends with an uptick, but whether that's noise or the start of a two-hump distribution remains to be seen.

john said...
This comment has been removed by a blog administrator.
Eric Schwitzgebel said...

John, if you have a theoretical point, please put it more neutrally.