I like to think of Blaise Pascal (1623 — 1662), the French mathematician, as the western world’s first practitioner of Twitter. His collected Pensées were brief, enigmatic thoughts about mathematics, religion, and philosophy. Collected after his death, they read like the tweets of the 17th century (though they were intended to be a much more comprehensive defense of religion).
In the Pensées, Pascal made his famous wager. We all bet with our lives on whether God exists or not. We can live as if God exists and practice the traditional forms and virtues of religion. Or we can do the opposite and ignore our religious duties, assuming that God does not exist. If we live as if God exists and we’re right then the rewards are infinite. If we’re wrong, the loss is finite — indeed it’s quite small. Thus, Pascal argues, it’s only rational to live a pious life. The wager is heavily stacked to that side.
In today’s world, we don’t spend much time wagering on God’s existence (perhaps we should) but we make lots of bets that are much like Pascal’s. The cumulative effects are enormous.
For instance, consider the Mediterranean diet. The diet — which features olive oil, nuts, vegetables, and fish but not much red meat — has been on our radar for a number of years now. Epidemiologists observed that people who live near the Mediterranean have a much lower rate of heart disease than would be expected. Maybe it’s the diet. Or maybe it’s something else, like religion, culture, family structure, heredity, etc.
So the evidence for the positive health effects of the diet was an observed correlation. We could see that the diet was correlated (inversely) to heart disease but we couldn’t be sure that it caused the lower rates. Maybe a hidden, third factor was in play. Still, we could make a version of Pascal’s wager: eat as if the Mediterranean diet does reduce the risk of heart disease. If we’re right, we live longer. If we’re wrong … well, we’ve missed out on a few tasty bacon cheeseburgers. Would you take the bet?
Last week, the level of evidence changed dramatically. A five-year, randomized Spanish study of nearly 7,5000 people was published. People who followed the Mediterranean diet had 30% fewer heart attacks, strokes, and deaths from heart disease than the control group. Since the study used the experimental method, we can now talk about cause and effect, not just correlation. Now will you take the bet?
Of course, there’s still some doubt about the results. It’s only one study; it hasn’t been replicated yet. It was conducted in Spain. Maybe we wouldn’t get the same results in America. Maybe there were methodological or measurement errors. Still, the evidence seems pretty strong and it points toward a version of Pascal’s classic wager.
We all make versions of Pascal’s wager every day but we rarely think about them. Perhaps it’s time that we pay more attention. Perhaps it’s time to think about what levels of evidence we need before we take the bet. Is correlation enough or do we need to prove cause and effect? Life is uncertain but perhaps we can make it more comfortable by thinking — and betting — logically. While you’re pondering that, I’m going to drizzle some olive oil over a bowl of walnuts. Drop by if you’re hungry.
As I’m teaching a course on critical thinking, I thought it would be useful to study the history of the concept. What have leading thinkers of the past conceived to be “critical thinking” and how have their perceptions changed over time?
One of the earliest — and most interesting –references that I’ve found is a sermon called the Kalama Sutta preached by the Buddha some five centuries before Christ. Often known as the “charter of free inquiry”, it lays out general tenets for discerning what is true.
Many religions hold that truth is revealed through scriptures or through institutions that are authorized to interpret scriptures. By contrast, Buddhism generally asserts that we have to ascertain truth for ourselves. So, how do we do that?
That was essentially the question that the Kalama people asked the Buddha when he passed through their village of Kesaputta. The Buddha’s sermon emphasizes the need to question statements asserted to be true. Further, the Buddha goes on to list multiple sources of error and cautions us to carefully examine assertions from those sources. According to Wikipedia, the Buddha identified the following sources of error:
Further, “Do not accept any doctrine from reverence, but first try it as gold is tried by fire.” The requires examination, reflection, and questioning and only that which is “conducive to the good” should be accepted as truth.
As Thanissaro Bhikkhu summarizes it, “any view or belief must be tested by the results it yields when put into practice; and — to guard against the possibility of any bias or limitations in one’s understanding of those results — they must further be checked against the experience of people who are wise.”
So how do the Buddhist commentaries compare to other philosophers? In the century after Buddha, Socrates is quoted as saying, “I know you won’t believe me, but the highest form of Human Excellence is to question oneself and others.” Almost 2,000 years later, Francis Bacon wrote, “Critical thinking is a desire to seek, patience to doubt, fondness to meditate, slowness to assert, readiness to consider, carefulness to dispose and set in order; and hatred for every kind of imposture.” A few hundred years later, Descartes wrote, “If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.” A hundred years after that, Voltaire wrote about the consequences of a failure of critical thinking, “Anyone who has the power to make you believe absurdities has the power to make you commit injustices.”
As the Swedes would say, there seems to be a “bright red thread” that ties all of these together. Go slowly. Ask questions. Be patient. Doubt your sources. Consider your own experience. Judge the evidence thoughtfully. For well over 2,000 years our philosophers — both Eastern and Western — have been saying essentially the same thing. It seems that we know what to do. Now all we have to do is to do it.