Bacon: Novum Organum

Francis Bacon was an English lawyer and writer who lived about 400 years ago. He worried that people were not learning much new about nature. They mostly read old books and argued about them. Bacon said: let's go and look, carefully, and collect lots of examples before we decide what's true.

He also warned about traps in our own minds. He called them "idols", meaning false pictures. For example, we tend to notice the times our lucky sock "worked" and forget the times it didn't. We get fooled by words that sound clear but aren't. And we believe things just because a famous teacher said them.

Bacon had a picture for good thinking. Some people are like ants: they just pile up facts. Some are like spiders: they spin webs out of their own heads. The best are like bees: they gather from the flowers, then work it into honey.

Who, when and why

Francis Bacon (1561–1626) was a lawyer, a member of Parliament, and in time Lord Chancellor of England, the highest judge in the land, under King James I. In 1621 he was charged with taking gifts from people whose cases were before him; he admitted the charges, was fined and removed from office, and spent his last years writing. All his life he planned a vast work to renew human knowledge, The Great Instauration (a "great restoring"). The Novum Organum (1620), "New Instrument", is its second part, a method for studying nature. The title answers Aristotle's logical works, long called the Organon, the "instrument" of thought.

The problem Bacon faced

Bacon saw that the useful arts, like printing, gunpowder and the compass, had changed the world, while the learning taught in universities had added little in centuries. Its method, as he saw it, jumped from a few observations straight to sweeping principles, then argued down from them. He wanted a slow, careful climb from many particular facts to modest conclusions, then to broader ones, testing at each step.

Idea 1: the idols of the mind

• Idols of the Tribe: errors shared by all humans. We see patterns that aren't there, notice what agrees with us and ignore what doesn't, and assume nature is as tidy as we would like.
• Idols of the Den (other translators say "Cave"): each person's own slant, from temperament, upbringing, reading and favorite subjects.
• Idols of the Market (or "Marketplace"): confusions that come from words, used in talk and trade. Names for things that don't exist, and vague words that mean different things to different people.
• Idols of the Theatre: received systems of philosophy and rules of proof, which Bacon compared to stage plays, each building a made-up world.

Bacon's description of the Idols of the Tribe includes a sharp observation (Book I, aphorism 46): once we hold an opinion, we pull everything into its support and pass over the cases against it. Psychologists today call this confirmation bias, and still find it in experiments.

Idea 2: induction by tables

Book II shows his method on an example: the nature of heat. First, a table of presence: many different things that are hot (sunlight, flame, boiling water, rubbing, quicklime with water, animals). Second, a table of absence: things like the first but not hot (moonlight, a glow-worm's light). Third, a table of degrees: cases where heat grows or shrinks with something else. Then comes exclusion: any guess about heat that fails a case is crossed out. Whatever survives is a first, careful conclusion, which he called the "first vintage", the first harvest of grapes.

Getting the history right

• Bacon did not invent "the scientific method". Careful observation and experiment were already practiced by people like Gilbert (whom Bacon criticized), the Italian anatomists and the craftsmen Bacon admired. Bacon's achievement was to argue for it powerfully and to make it a public program.
• He underrated mathematics and bold guesses. The great advances of his century, Kepler's laws, Galileo's motion and Newton's gravity, came from mathematics and daring hypotheses tested against the data, more than from tables of instances. Bacon also did not accept Copernicus.
• His conclusion about heat was close. Later physics (the kinetic theory of the 1800s) found that heat is indeed the random motion of a body's molecules, though by a very different route.
• The snow and the chicken. A story says Bacon died after stopping his carriage to stuff a chicken with snow, to see if cold would keep meat fresh, and catching a chill. It was told decades later by John Aubrey; historians think it may be partly true, but no one is sure.

What later science kept, and what it changed

Kept: the demand to test ideas against many cases; the special power of a single counterexample (a point the 20th-century philosopher Karl Popper made central); the warning about the mind's biases; and the hope that science would improve human life. The Royal Society of London, founded in 1660, named Bacon as its inspiration. Changed: no one now thinks science can be done by mechanically filling in tables. Scientists propose hypotheses, often in mathematical form, and design experiments to test them.

Knowledge and power. In aphorism 3 Bacon writes that human knowledge and human power come to the same thing, because we can only produce an effect if we know its cause, and nature is mastered only by obeying her. What do you think he meant by obeying nature? Is all knowledge a kind of power?

Bacon and his critics. Bacon hoped science would bring relief to human suffering, and much of it has. Some later writers worried that his language of mastering nature encouraged harm to the natural world; others reply that he also insisted we must understand nature before we can use it, and that the goal was charity. Readers can weigh both views.

Compare. Descartes's Discourse on Method (1637) offers a different method: start from what is certain and reason down in careful steps. Galileo combines mathematics with experiment. Which of these is closest to how you solve problems?

Big questions. How many examples are enough to be sure? Can we ever escape our own idols, or only learn to watch for them?