The quote of the year comes from Evan
“I thought once
speak freely and
ideas, the world is
to be a better place. I
was wrong about
“The world is networked as never before.”
Yes, it’s true.
Today’s social networks are the biggest and
The map plots every city pair with a great-circle line, the transparency of which is
determined by the number of friend-pairs in those cities.
But it hasn’t worked out quite as dreamed
by the Technoptimists
“All people want to connect. … the
great arc of human history bends
towards people coming together in
ever-greater numbers—from tribes
to cities to nations—to achieve
things we couldn’t on our own.”
CEO OF FACEBOOK
2016:The annus horribilis of the liberal
2016:The annus horribilis of the liberal
2017: Storm clouds are gathering over
What happened? The answer has to do with
the inherent properties of networks
Far from being new, networks have always
been ubiquitous, in Nature …
Left: neural network of C. elegans worm. Right: partial food web for the
“Scotian Shelf”. Arrows go from the prey species to the predator species.
Davis; Newhall and Traud
… and in the social life of humans,
regardless of technology
A simple (but tragic) network. Hamlet leads in terms of degree centrality
(sixteen, compared with Claudius’s thirteen).The “zone of death” in the play
encompasses characters connected to both Hamlet and Claudius.
Unfortunately, we historians tend to be
biased in favor of hierarchies
Mural in the Cattedrale di Santa
Maria Assunta, island of Torcello,
Venice. Hierarchy is from
ἱεραρχία (hierarchia), “rule of a
We focus on the tower and not enough on
Piazza del Campo in Siena, with the shadow of Torre del Mangia.
This is partly because we look for answers
in archives, which hierarchies tend to keep
But it’s also because we don’t see the
implications of network science for our work
Varieties of network. SF: scale-free, ER: Erdös-Renyi (randomly constructed).
So, here are six big things I’ve learned:
1. Not many men are islands …
Individuals are nodes connected by edges—but not all nodes or edges are
equal; some nodes are central and some edges are bridges (Freeman). Above:
Jacob Moreno’s “sociogram” of a residential cottage for reform school girls.
… and birds of a feather flock together …
Because of homophily, nodes tend to form clusters of similar properties or
attitudes (Zachary). Above:The network of the friendships in a U.S. high
school, from the National Longitudinal Survey of Adolescent to Adult Health.
… which explains network polarization
Network graph of moral contagion shaded by political ideology.The graph
represents a depiction of messages containing moral and emotional language,
and their retweet activity, across all political topics (gun control, same-sex
marriage, climate change). Nodes represent a user who sent a message, and
edges (lines) represent a user retweeting another user.The two large
communities were shaded based on the mean ideology of each respective
community (blue = liberal, red = conservative mean).
Brady et al. (2017)
For most of history, hierarchies dominated
Prices and quantities of books and PCs, 1490s-1630s and 1977-2004,
But there have been two eras of enhanced
connectedness.The first began around 1500
When the printing press empowered
Martin Luther’s heresy, a network was born
Johannes Gutenberg (c. 1440-50) “invents” the printing press in Strasbourg.
Luther’s dream was of a “priesthood of all
“Scripture ... sets before us Christ alone as mediator, atoning sacrifice, high
priest, and intercessor.”—Augsburg Confession Art. XXI.
The actual result of the Reformation was
not harmony but polarization and conflict
St. Bartholomew’s Day massacre of Huguenots, Paris, 1572.
But it proved impossible to kill Protestant
networks, even with mass executions
The English Protestant network before (left) and after (right) John Bradford’s
execution on July 1, 1555. His death cut off an entire subnetwork (in white).
Ahnert and Ahnert (2015)
2. It’s a small world because weak ties are strong
Acquaintances are the bridges between clusters (Granovetter) and they are
what make the world small (Milgram). Above: seven degrees of separation
between a widowed clerk in Omaha, Nebraska, and a Boston stockbroker.
Like the Reformation, the Enlightenment
was a network-driven phenomenon
The Scottish Enlightenment’s network of correspondence
Mapping the Republic of Letters project
The amazing thing was how much further
the Enlightenment traveled
Voltaire’s network of correspondence, illustrating the importance of “weak
ties”—long distance acquaintances that helped spread his ideas
Mapping the Republic of Letters project
The American Revolution was also a
The revolutionary network in Boston, c. 1775. Note the betweenness centrality
of Paul Revere and Joseph Warren. Removing either or both of them would
significantly have reduced the density of the network. Individuals are grouped
together into single nodes according to shared club memberships.
And Freemasonry was a key network that
connected many of the Founding Fathers
George Washington, Founding Father and Freemason.
3. Structure determines virality
A hierarchy is a special kind of network.The node at the top has the highest
betweenness centrality. Other nodes can communicate with the majority of
other nodes only through that one ruling hub.
Hierarchical order was not easily restored
The Congress of Vienna: but the “cake of kings” could only be cut up with the
help of the Rothschilds’ financial network.
But the technologies of the industrial age
favored a super-hub (London)
The mid 20th century was the zenith of
telephone-enabled totalitarian hierarchy
Mid-century American capitalism was
hierarchical in its structures, too
Alfred Sloan’s “Organization Study” for GM, 1921.
Yet even in this hierarchical world, a
network could break out
Martin Luther King, Jr., in Montgomery, Alabama
4. Networks never sleep
Networks are complex adaptive systems with emergent properties and phase
transitions (Barabási). Above: Each dot represents $100M in exports, coloured by
product type. Central component is “machinery, electrical” and “transportation.”
Center for Economic Development, Harvard, Globe of Economic Complexity (2017)
The Second Networked Age—our own—
began in the 1970s
Kissinger understood that networks were
growing more powerful than hierarchies
The Nixon-Ford network (who refers to whom in administration memoirs).
Silicon Valley was a consequence rather than a
cause of weakening central control
Arpanet (1969), DNS (1984), www (1989), Jobs and Gates (1991).
After all, you did not need much technology
to organize a network of anti-Soviet dissent
Networks of Polish opposition in 1980-81.
5. Networks network—and it takes one to beat one
The results of interaction can be innovation and invention (Padgett and
Powell), or outage in the face of attack. Above: Cambridge Apostles Keynes,
Strachey and Burgess; and Burgess’s KGB controller, Arnold Deutsch.
The 9/11 attacks were by a network against a
The 9/11 plotters’ network, as visualized by Vladis Krebs in 2002.
Yet the financial crisis of 2008 was more costly
than the terrorist attacks of 2001
The bankruptcy of Lehman Brothers, 9/15/2008
What technology had done was to make
networks bigger—and more vulnerable
Then ISIS revealed that the worst ideology
could be spread virally
The 66 “most important
jihadi and support sites for
jihad and the mujahideen
on Twitter,” as
recommended by jihadist
blogger Ahmad ‘Abdallah
in February 2013.
The network of President Trump, tracing all known connections from Trump
and the Trump Organization to other individuals and organizations.
And the Trump network disrupted
American politics …
… with little help from another network in
Five of the eight richest men in the world: Bill Gates ($76bn), Jeff Bezos ($45bn),
Mark Zuckerberg ($45bn), Larry Ellison ($44bn), Michael Bloomberg ($40bn).
6. Networks are profoundly inegalitarian
After 2004, the rest of us caught up with the
financial world: we all got networked
This was supposed to usher in a brave new
world of netizens
Instead, a new hierarchy of near-
The U.S. government sought to harness the
power of the big tech companies
But the new networks could not so easily be
integrated into old power structures
We are back where we started: with the
contest between the square and the tower