Transcript of Commencement Address
Science and Human Freedom
by Judea Pearl
June 21, 2007

Chancellor Peterson, President Naylor, members of the faculty, parents, and especially, the graduates:

It is a great honor for me to receive this Doctorate degree from your esteemed university, and it is also a timely honor -- I've been waiting more than 40 years for an opportunity to consummate my PhD degree in an official graduation ceremony because, and this is a difficult confession for me to make -- I skipped my other graduation ceremonies, all three of them.

When my Bachelor degree was awarded, I was on board of a ship, heading to America.

And when the time came to get my PhD degree, I had a tough dilemma, the ceremony fell on the very same day that I was to receive a Master degree in Physics, in a different University, and I could not make up my mind between the two. At the end of the day I stayed home and had the two diplomas delivered by mail.

This was my teenage rebellion, very fashionable in the 1960s: "Who cares for ceremonies and symbols, caps, gowns and speeches? It is the knowledge that counts, right?"


I have another confession to make today -- a secret that I kept even from my wife. I truly regret not having gone to my graduation in 1965 which, in some strange sense, caused me to feel that my degree is somewhat fake or improperly earned, even though the diploma itself is properly signed and well encased, I am sure, in a very safe place at home.

And I should have known better.

Coming from computer science -- the science of symbols, I should have known the importance of symbols to the workings of the mind, and to the workings of society.

I should have known that, in all primitive societies, initiations to adulthood are consummated not by signing documents, not even by passing a test, but by a ritual communal dance, with feather hats and dragon masks and all the tribal chiefs and the village elderly and women and children present.

And I should have known that the neural architecture of modern man is not much different than that of the hunting caveman.

I know better now. I know that it is not the signature on your diploma that counts, but the statement of deservedness that you will be making by stepping up to this stage and receiving your degree in the presence of your teachers, families and peers who will bear witness to, and cheerfully approve of your claim for accomplishment -- that is what counts, and that is what you will remember.

And that is why we put on these funny caps and gowns, so you will retain a visual memory of this tribal dance.


Because it is only through a communal testimony that your accomplishments becomes embedded in a relevant and meaningful context, larger than yourself, and it is through this context of an extended tribal community that you will be able to apply what you have learned in a way that would make it meaningful and rewarding to you for the rest of your life.

What is this tribal community that you are joining today?

The cap and gown that I wear unveil its identity; it is the tribe of "scientific freedom fighters."

This cap and gown were first worn at the University of Padua, Italy, in the 13-14th century, the place where Galileo later taught and where he invented the telescope (1608) and discovered the amazing fact that physics listens to the language of algebra, (1632).

Galileo is one of my heroes because, to me, he represents the essence of scientific pursuit. Just to have the illusion that I am emulating Galileo, in his funny outfit, sends a thrill down my spine.

Galileo always reminds me of the inextricable connection between science and freedom.

How? Because Galileo showed that to be a scientist you must have both: respect for the truth, and the audacity to believe that you can find it.

This might sound trivial -- science, by definition, is about truth, so what's all this talk about freedom.

It is not so trivial. Truth can be elusive, even in our times, covered by the heavy fog of fear and hidden agenda. It is only after the murder of my son Danny that I came to appreciate how hard it is, even in the age of Internet, to stay the course of truth.

Just two weeks ago, Abdurrahman Wahid, the former president of Indonesia, and Israel Lau, the former Chief Rabbi of Israel made an interesting observation, published in the Wall Street Journal: "the countries in which Holocaust denial is most rampant also tend to be the ones that are most economically backward and politically repressive."

Now what is the connection, you might ask, between Holocaust Denial and repressiveness? Is lack of freedom the cause of truth denial, or the other way around? The idea is, said Wahid and Lau, that "Those who are dishonest when it comes to the truth of the past, are hardly in a position to reckon honestly with the problems of the present."

What Galileo showed us is that you cannot have one honesty without the other; scientific truth demands scientific honesty, and scientific honesty demands intellectual honesty overall.

We all remember the 1000 years of zero scientific progress through the middle ages -- what caused it? The conventional answer is that the Church was repressive of scientific discourse. But this could not be the whole story, there was no repressive Church in the Muslim world. And Muslim scientists had access to the richest libraries of the time, well-funded astronomical observatories and all the writings of the Greek and Roman philosophers. So why didn't a genius like Galileo emerge in Cordoba or Alexandria or Baghdad in the 8th or 9th century?

Why was science held back, in almost total stagnation for 1000 years, until, as though by miracle, the genius of Copernicus, Vieta and Galileo emerged in dark-ages Europe, of all places? Can you imagine where mankind would be today had the renaissance and the scientific revolution taken place in the 5th century instead of the 15th?

What Galileo taught us is that permission to read, translate, observe and use fancy equipment is not enough; the development of Science requires a restless and rebellious spirit, a spirit that puts the individual at the center of the universe and proclaims: "I don't care about Aristotle and his fancy books, I want to see these two rocks dropped from the tower of Pisa, and I want to see them with my own two eyes."

In other words, what Galileo showed us is that you cannot truly search for the truth unless you are free to rebel against the detractors of truth: conventional wisdom, peer pressure, sacred cows, wishful thinking, revered authority and hidden agenda, in short, free to perceive yourself as an AGENT, in control of your destiny, not an OBJECT, at the mercy of destiny.

Remarkably, this Western perception of man as a free agent, sometimes called the "scientific philosophy" it not always taken for granted, even today.

"The West is morally bankrupt" declares Professor Tariq Ramadan, the darling star of European intellectuals.

"Take from the West all its science and technology," says Scheik Yusuf Qaradawi to his Al Jezeera listeners, "but you must reject Western philosophy, because it is corrupt at its roots by the pagan philosophies of Greece and Rome."

Sorry to disappoint you Scheik Yusuf Qaradawi, but you can't have science and technology without Western philosophy of freedom, honesty and individual AGENCY; it has been tried before, for 1000 years, in your own courtyard, and failed.

And Sorry to disappoint you Professor Ramadan, but Western civilization is mighty proud of its ethics, values and achievements, and "bankruptcy" is not in its lexicon -- far from it.
The spirit of the West shines brightly today through the works of hundreds of humble yet courageous and principled young scientists and engineers who are graduating from this great university.

This spirit is rooted indeed in the skeptical inquiry of the pagan Socrates and the moral clarity of the Biblical Jeremiah, and the rebellious spirit of Galileo, but behold, it shows no sign of bankruptcy or decline -- it is, in fact, the only beacon of hope and moral courage for humanity today.

So, I congratulate you all today on joining the extended family of Socrates, Galileo and Einstein, and I welcome you to the tribal dance of science, the dance of freedom and humanity.

Thank you.