# Network Visualization & Analysis of the Stanford Encyclopedia of Philosophy

## Introduction

The Stanford Encyclopedia of Philosophy (hereafter, SEP) is a "dynamic reference work" that has a significant influence in and on academic philosophy. The SEP is also an enormous resource of data about academic philosophy. This project is an attempt to represent the network structure of the SEP, visualize its global properties, and understand the structure of academic philosophy as represented in the SEP.

## Methodology

Four times per year the SEP is archived, creating a collection of snapshots of the entire document from Fall 1997 until Fall 2018. In total, this is 84 fixed versions of the SEP. A simple Perl script collects the data from each article, and identifies each time an article contains a hyperlink to another article. The script then prints two *.csv files that list the articles and the links between them.

## R Code

Once the data is loaded into R, we can use it to create the network objects.

data <- read.csv("data/fall2000_edge_list.txt", header = TRUE)
g <- graph_from_data_frame(as.data.frame(data), directed = TRUE)
V(g)$label <- V(g)$name
V(g)$degree <- degree(g) V(g)$betweenness <- betweenness(g,V(g),directed=TRUE)
V(g)\$group <- membership(cluster_walktrap(g))

After creating the grap object (in this case with the igraph package) and computing a few properties, we can use several packages to visualize the graph.

## Example Graph: Fall 2000

This graph represents one of the early archives of the SEP. The nodes are sized by centrality in the graph and colored by community detection. You can hover, zoom, click and drag to manipulate the graph.

The community detection shows the early divisions aomong the SEP: broad areas of philosophy like value theory, metaphysics, epistemology, logic, and language are grouped together.

As later years of the SEP bear out, the articles that tend to score highest on centrality measures such as eigenvector centrality and betweenness are disproportionately articles about individual philosophers.