Science helps us understand the essential tension
between orthodoxy and heresy in science

In a 1987 lecture entitled “The Burden of Skepticism,” astronomer Carl Sagan succinctly summarized the delicate compromise between tradition and change:

It seems to me what is called for is an exquisite balance between two conflicting needs: the most skeptical scrutiny of all hypotheses that are served up to us and at the same time a great openness to new ideas … If you are only skeptical, then no new ideas make it through to you … On the other hand, if you are open to the point of gullibility and have not an ounce of skeptical sense in you, then you cannot distinguish the useful ideas from the worthless ones.

Why, we might inquire, do some people prefer orthodoxy while others favor heresy? Is there a personality trait for preferring tradition and another for change? This is an important question because the answer helps to explain why in the history of science some chose to support radical new ideas while others opposed them.

In 1990 David W. Swift published SETI Pioneers: Scientists Talk about Their Search for Extraterrestrial Intelligence, in which he identified an overabundance of firstborns, including Sagan. But is it a statistically significant overabundance? Swift, a sociologist at the University of Hawaii, did not compute this, but University of California at Berkeley psychologist Frank J. Sulloway and I did. Eight is the expected number of firstborns based on the number of siblings the SETI pioneers had, but 12 is the observed number. This difference is statistically significant at the 95 percent level of confidence.

So what? In Sulloway’s book Born to Rebel, he presents a summary of 196 controlled birth-order findings classified according to the Five-Factor Model of Personality:

Conscientiousness. Firstborns are more responsible, achievement oriented, organized, and planful.

Agreeableness. Laterborns are more easygoing, cooperative, and popular.

Openness to Experience. Firstborns are more conforming, traditional, and closely identified with parents.

Extroversion. Firstborns are more extroverted, assertive, and likely to exhibit leadership.

Neuroticism. Firstborns are more jealous, anxious, neurotic, fearful, and likely to affiliate under stress.

To evaluate Sagan’s personality, Sulloway and I requested a number of his friends to rate him on a standardized personality inventory of 40 descriptive adjectives using a nine-step scale between them. For example, I see Carl Sagan as someone who was: hardworking or lackadaisical, tough-minded or tender- minded, rebellious or conforming, et cetera.

The following results are in percentile rankings relative to Sulloway’s database of more than 7,276 subjects.

Most consistent with his firstborn status was Sagan’s exceptionally high ranking — 88th percentile — on conscientiousness (ambitiousness, dutifulness) and his strikingly low ranking of the 13th percentile on agreeableness (tender-mindedness, modesty). But his openness to experience (preference for novelty) was nearly off the scale at the 97th percentile. Why? First, birth order is hardly the only influence on openness and can be affected by cultural influences and social attitudes — Sagan was raised in a socially liberal Jewish family, and he was mentored by such scientific revolutionaries as Joshua Lederberg and H. J. Muller. Second, openness also includes an “intellectual” component, and firstborns tend to excel at intellectual pursuits, as reflected by their higher I.Q. scores and a tendency to win more Nobel Prizes in science.

Here is the key to understanding the exquisite balance between tradition and change: Sagan’s high openness led him to be a SETI pioneer, but his high conscientiousness made him skeptical of UFOs. Considering the example of Sagan, we can glean a valuable lesson on how science operates effectively in discriminating sense from nonsense, and it is science that helps us understand how and why this should be so. How recursive!