Tuesday Book: A flawed life of science's fallible advocate

Carl Sagan: A Life by Keay Davidson (John Wiley, pounds 19.50)

I KNEW Carl Sagan in the early Seventies, when he was already an important member of the astronomy community, but before he became a media superstar. What I saw was a very private, even shy, individual, driven by the search for scientific truth, but also deeply concerned about the way science was presented to the public, and even more so by its perversion in such activities as the manufacture of nuclear weapons.

As Sagan's career as the public face of science took off, I saw the same drives writ large - communication about science in the TV series Cosmos and a string of books, the defence of science against the irrational ideas of people such as Immanuel Velikovsky, his work on the "nuclear winter" and opposition to the Strategic Defense Initiative.

The Sagan described in Keay Davidson's new biography is less likeable, driven as much by self-promotion as by a desire for scientific truth and a better world. According to this version, fame went to Sagan's head; he fell out with many old friends, and his two failed marriages confirm his fallibility.

I never met Sagan after 1974, and so cannot speak from personal experience (but Davidson never met him at all, and can only report the views of the people who now blame Sagan for the disintegration of old friendships). But it seems to me that he may have confused Sagan's sometimes ruthless push to promote science with something more personal. The best vehicle Sagan the scientist had for promoting science was Sagan the TV personality, and he used himself as a means to that end.

That this point is worth debating highlights the intriguing thing about Sagan. He was not really a great scientist - pretty good, but nothing special. His importance is entirely as a communicator, whether about astronomy to the general public, or about the hazards of nuclear war to the US government. By exaggerating the importance of Sagan's scientific work, Davidson misses an opportunity to discuss this crucial factor in the balance of Sagan's career. And the fact that Sagan was not a top-notch scientist also explains much of the jealousy experienced by his peers.

We are left with a flawed biography, when it comes to insights into its subject's character, but a worthwhile account of the facts of Sagan's life. Although this is far from being the definitive biography, it is an enjoyable read and will more than suffice for now.

As is so often the case with biographies, the most fascinating part concerns the subject's early life. Like so many of his contemporaries who made a mark in late-20th-century American science, Sagan (born in New York in 1934) was a child of Jewish immigrants. His parents encouraged his interest in science, and he benefited from the opening up of the US higher education system to Jews (previously subject to quotas) after the Second World War.

The most worrying encounter of Sagan's early teens was a conversation with his grandfather, who spoke no English. Through an interpreter, he asked what young Carl meant to do for a living. He replied that he wanted to be an astronomer. "Yes," replied the old man, "But how will you make a living?" Some 35 years later, Sagan received a $2m advance for his novel Contact - then the biggest ever for a book that had not yet been written. Some living.

The reviewer's books include biographies of Stephen Hawking and Richard Feynman