The Idols of the Cave are the idols of the individual man. For everyone (besides the errors common to human nature in general) has a cave or den of his own, which refracts and discolors the light of nature, owing either to his own proper and peculiar nature; or to his education and conversation with others; or to the reading of books, and the authority of those whom he esteems and admires; or to the differences of impressions, accordingly as they take place in a mind preoccupied and predisposed or in a mind indifferent and settled; or the like. So that the spirit of man (according as it is meted out to different individuals) is in fact a thing variable and full of perturbation, and governed as it were by chance. Whence it was well observed by Heraclitus that men look for sciences in their own lesser worlds, and not in the greater or common world.
—Francis Bacon, Novum Organum
Nothing about this week’s episode of Cosmos was black and white. On one hand, the episode’s focus on light took us from the discovery of the camera obscura, to the use of prisms to separate light’s colors, to the discovery of Fraunhofer lines and spectroscopy which turn those lines into evidence about the components of matter (even distant stars), to the challenge of understanding dark matter (which has mass but doesn’t interact with light). On the other hand, it illuminated the question of what science is, how we developed science, and what we need to do to foster scientific discovery. Along the way, it showed clearly why creationism and other science denials are overshadowed by real science.
For the first time thus far in the Cosmos reboot, we explored the history of science outside of Europe, with Chinese philosopher Mo Tzu and Arab astronomer Abu al-Haytham featured prominently. Tyson credited both with laying foundations for “the scientific approach.” This was a welcome acknowledgment that science developed as a global phenomenon, and his account of Joseph Fraunhofer’s path from indentured servitude to scientific pre-eminence reminded us that science doesn’t depend on economic class, either. Referring to Fraunhofer’s rescue from the collapsed building in which he performed menial labor, Tyson observed, “You never know where the next genius will come from. How many of them do we leave in the rubble?”
Science also operates across religious lines, a point emphasized in talking about al-Haytham. The Caliphate he lived in “was open to new ideas and questioning,” seeking, preserving, and synthesizing knowledge from around the world. “Christian and Jewish scholars were honored guests…Much of the light of ancient Greek science would have been permanently extinguished if not for their efforts. The reawakening to science that took place in Europe hundreds of years later was kindled by a flame that had been long tended by Islamic scholars and scientists.” Science is for everyone, for anyone committed to understanding the world we all share, regardless of geography or class or religion (though the contributions of women remain absent from Cosmos; this is the third episode to feature William Herschel without mentioning his sister, who assisted his research and advanced her own research programs in parallel with William’s).
Science, Tyson emphasized, is all about an approach we take to the world. “Science needs the light of free expression to flourish. It depends on the fearless questioning of authority, and the open exchange of ideas.” The best scientists “question everything, especially those things that everyone else took for granted.” And the rules come to us across cultural barriers, from practice and experience. As Tyson explained:
Ibn Al-Haytham was the first person ever to set down the rules of science. He created an error-correcting mechanism. A systematic and relentless way to sift out misconceptions in our way of thinking.
[al-Haytham’s voice]: ‘Finding truth is difficult. And the road to it is rough. As seekers of the truth you will be wise to withhold judgment and not simply put your trust in the writings of the ancients. You must question and critically examine those writings from every side. You must admit only to argument and experiment, and not to the sayings of any person. For every human being is vulnerable to all kinds of imperfection. As seekers of the truth we must also suspect and question our own ideas as we perform our investigations, to avoid falling into prejudice or careless thinking. Take this course and truth will be revealed to you.’
“This,” Tyson adds, “is the method of science.” Al-Haytham’s ideas are not so different from what Francis Bacon codified as his four classes of idols in 1620, in the first European formulation of an organized scientific method, the foundation for modern understandings of scientific processes.
These idols are biases to which all humans can fall prey: Idols of the Tribe, Idols of the Cave, Idols of the Market Place, and Idols of the Theater. Bacon, like al-Haytham, saw his scientific method as a way to acknowledge and overcome these biases, and even to turn them to our advantage by playing different people’s biases against themselves. Peer review, rejecting tradition in favor of empirical evidence, operating without limits by political authority or personal ideology, and open and unambiguous communication of results all were essential to the approaches developed by Bacon, al-Haytham, and a global community of scholars. Bacon observed, “the human understanding is like a false mirror, which, receiving rays irregularly, distorts and discolors the nature of things by mingling its own nature with it.” The rules of science exist to correct that flawed lens.
Rejection of these processes and rules, carefully refined by students of the world for generations, are exactly why creationism, climate change denial, and other science denials fail. They mimic science, but rather than trying to overturn the Idols Bacon identified, they worship them. When new evidence challenges what they took for granted, they reject the new evidence. Rather than correcting the aberrations introduced by our human flaws, the various kinds of science denial thrive by reinforcing them.
“Confining our perception of nature to visible light is like listening to music in only one octave,” Tyson said as he closed the episode. It was a nod to the diversity and pluralism that science thrives on, a diversity of people, ideas, religions, and perspectives. Just as the image from a camera obscura sharpens as the aperture narrows, science succeeds by taking in messy, mixed input and screening it all through the narrow gap afforded by our shared, empirical reality, and that limit is what gives it such tremendous, awe-inspiring, power.