A Visionary and a Scoundrel
The Commercial and Political Atlas and Statistical
Breviary. William Playfair. Edited and introduced by Howard
Wainer and Ian Spence. Cambridge University Press, 2005. $39.99.
Anyone who has clicked the popular button that commands a
spreadsheet computer program to make a chart has experienced the
satisfaction of seeing a confusing grid of numbers resolve into
crisp bars. It is hard now to imagine how we ever got by without
visual tools for understanding masses of data. But of course such
devices as the bar graph, the time-series line graph and the pie
chart had to be invented. The peculiar man who came up with all
three was William Playfair (1759-1823), a Scot who was convinced he
could influence Britain's course with visual explanations of
macroeconomic trends. Endowed with drafting experience and confident
in the power of graphical language, he presented his polemics in a
new form: annotated graphs that vividly highlighted trade gaps and
the growing national debt.
Although Edward Tufte (author of The Visual Display of
Quantitative Information ) and others have noted
Playfair's role as the leading originator of modern statistical
graphics, access to his work has heretofore been limited. Finally
Playfair can speak for himself: Facsimiles of two of his most
important works—the 1801 edition of The Commercial and
Political Atlas, and The Statistical
Breviary of the same year—have now been published in
one small, affordable volume.
The vision that emerges from Playfair's pages is one of startling
clarity and foresight. Even those who have seen samples of his
charts—perhaps in Tufte's 1983 book or in statistician Howard
Wainer's 2005 volume, Graphic Discovery: A Trout in the Milk and
Other Visual Adventures—will find new treasures here,
all in color and some on foldout pages. The facsimiles are prefaced
by a lively introduction in which the editors—Wainer and
psychologist Ian Spence—give us a glimpse of the work's
creator and his times.
Born in a village near Dundee, William was the younger brother of
John Playfair, who became a distinguished mathematician, physicist
and geologist. After learning drafting in the employ of the
engineer-inventors Andrew Meikle and James Watt, William sought his
fortune in London. Failing at the first of several doomed business
ventures, he turned to writing about economics. The Commercial
and Political Atlas—a series of 44 graphs charting
selected trends in England's trade and national finances, each
followed by remarks and observations—appeared in a preliminary
edition circulated privately in 1785.
Playfair's Atlas was a historical singularity. Graphs and
charts did not, as one might have assumed, coevolve with science,
business and government. Rather, the new medium emerged full-blown
in Playfair's works (although other graphic forms did crop up in
isolated experiments around the same time). And then, just as
quickly, it vanished.
Graphic explanation simply did not catch on. Excellently constructed
by today's standards, Playfair's charts were in his own day neither
praised nor imitated. He eagerly sent copies to well-placed
acquaintances, yet most took no interest. One of the few exceptions
was the French king Louis XVI, who understood immediately that the
charts "spoke all languages."
Another century or so would pass before the emerging field of
statistics grasped the power and utility of graphical presentation.
Wainer and Spence attribute the slow adoption of statistical charts
to the intellectual climate of Playfair's Britain, where empiricism
was ascendant. The empiricists, who argued that knowledge arises
from sensory experience, recorded observations and plotted them on
line graphs in their notebooks. But they valued rigor and precision,
and pictures created to represent observations were necessarily less
accurate and more interpretive than were numbers themselves. A
"general mistrust of pictorial representation" in British
science continued into the early 19th century (and a cautious
skepticism about graphic presentation of data remains part of
scientific culture today). Watt tactfully urged Playfair to provide
tables to support his arguments, pointing out that "the charts
now seem to rest on your own authority, and it will naturally be
enquired from whence you have derived your intelligence."
It didn't help matters that Playfair was a recklessly outspoken
iconoclast—and even a bit of a scoundrel. Afflicted by a
proclivity for questionable schemes when in financial straits,
Playfair waded in and out of legal hot water while working on the
Atlas and the Breviary. Convicted of libel in
England and swindling in France, he later bungled an extortion
attempt. His standing impaired by his checkered reputation, he was
in his final years still publishing fine charts and advocating that
others do so, but his arguments fell on deaf ears.
Wainer and Spence point out that innovation is frequently the
product of an unconventional individual. Playfair fits this
description, yet in the opening pages of the Atlas, he
builds a case for his graphical approach on precedent, noting the
practices of drawing family trees and creating historical time
lines. "The studies of history, genealogy, and
chronology," he says, "have been much improved by
copper-plate charts." A data table, he insists, can leave the
reader with only a "very faint and partial idea of what he has read."
Pointing to cartography as an established graphical form, Playfair
urges the reader to see how a financial chart can map a different
physical reality, money. Financial graphs, he says, can be
understood as "piles of guineas represented on paper, and on a
small scale, in which an inch (suppose) represents the thickness of
five millions of guineas, as in geography it does the breadth of a river."
Playfair's most intriguing arguments are those in which he
anticipates the findings of experiments on cognition and perception
that were not carried out until two centuries later. Graphical
representation, he argues in the Breviary, can
"facilitate the attainment of information, and aid the memory
in retaining it."
He had already proved the point in the 1786 edition of the
Atlas, with the first published bar chart, which
illuminated Scotland's 1781 trade surplus with America and its
simultaneous trade deficit with Russia. It conveys its message to
the eye in an instant. Like Playfair's other graphs, it has grid
lines, axis labels and hatching, designed with a thoughtfulness that
makers of graphing software would do well to emulate.
Playfair's graphs derive extra explanatory power from his detailed
annotations. In a 250-year comparison between the revenues of
England and those of France, he marks off the reign of each king.
"We see the two nations advancing in revenue and expenditure
with a pretty equal pace," the text explains, "till the
revolution of 1789 changed the business, and has very nearly freed
France from all her debts, while it has almost doubled those of England."
Within a large chart in the Breviary one finds perhaps the
most curious invention: a pie chart (see illustration). It
is a crude attempt that seems nevertheless to have been drawn with
delight. The pie-slicing is a solution to the problem of how to
display land areas in an empire with more than two dominions. Yet
here Playfair stumbles when he attempts to represent three
quantities for each empire or nation—land area, fiscal data
and population—in the same two-dimensional space. In so doing
he introduces distortions, foreshadowing a common limitation of
modern two-dimensional graphs. Playfair's discussion of this chart,
though, seems carefully designed to restrain inference; he
understood what his graphics could not do.
It's worth asking whether we've made substantial progress in the
visual representation of statistical data since Playfair's time.
Certainly graphs are widely used today for exactly the purposes he
proposed. Even though tables retain the advantages of precision and
transparency, rarely do we stare at tabular data to make statistical
inferences; observations are plotted as soon as they are collected.
Technological change and society's need to make sense of the streams
of data flowing from computers have made graphic representation of
data ubiquitous. The Web, PowerPoint, Flash and statistics and
spreadsheet programs have turned every computer user into a graphics
producer and consumer.
However, many a modern graph does mask or misrepresent the
properties of the underlying data. Today, equipped with powerful
tools that do the searching for us, we may be less skilled at seeing
patterns in raw data than were the early empiricists. Certainly we
rarely think the way Playfair did about why and how to make a graph.
In an age of exploding visual stimulation, we rarely even take the
time to rest our eyes on a carefully crafted, simple chart and
consider why it works so well. For those in search of such pleasure,
I recommend passing a quiet afternoon with a certain con man from Dundee.