Map of life expectancy at birth from Global Education Project.

Monday, March 12, 2007

Sunday Sermonette: What you don't know is good for you

(I really did write this on Sunday, but my Internet access went down just as I was posting it. So, here it is a day late.)

While religious fundamentalism has always been with us, it seems resurgent now, at least in the United States. But polls don't show that more people hold to fundamentalist doctrines, on the contrary. While Americans remain far more likely to hold irrational beliefs than do Europeans -- disturbingly so, in fact, including a majority who do not believe in the reality of Darwinian evolution -- secularism and, indeed, atheism have been growing in the United States. Nevertheless, atavistic fundamentalist religion has become increasingly assertive, political and uncompromising.

This is a reaction to a newly felt threat from reason, a sign of weakness rather than growing power. It is a symptom of growing discomfort with uncertainty. Now many people are openly challenging faith, and doing so with rationally unassailable evidence and arguments. No matter how fervently one believes and prays and denounces, that vexing, itch-making mosquito of doubt must now always flit about the edge of the true believers consciousness.

To live by reason, however, is to happily live by doubt. Reason does not, as some people imagine, sort propositions into three categories, false, unproven and true. Rather, ideas are on a continuum, from as surely false as they can be - e.g., the earth is flat, the universe is 6,000 years old - to as surely true as any can be - e.g., the earth revolves around the sun. But the domain of science is neither of these. It is everything in between, the realm of ignorance and uncertainty.

Evaluating scientific claims is not a matter of running them through a truth detector. There is no formula, no single "scientific method," that can assign a degree of certainty to a claim. Rather, weighing scientific evidence requires assessing what kind of evidence it is -- whether observational or experimental -- and its quality as such, including the reliability of observations, the strength of inferences including the probabilities derived from statistical analysis, the cumulative weight of evidence from multiple sources, and the subtractive force of apparently contradictory evidence. Since nobody can be an expert in more than a small portion of scientific endeavor, we must also assess assertions in the rest of the sphere of knowledge based on the general picture we can gain of how they are derived, and the reputation of the people who make them.

Scientific understanding of the world gains credence from coherence. When the pieces from various lines of inquiry fit together, we become more confident in each piece. So, biologists trust the work of geologists because their findings cohere; equally, geologists trust the work of astronomers. It all makes sense as a single picture. When something doesn't seem to fit, we become less certain. Is there something wrong with the odd piece, or with the larger theory into with which it seems not to accord? Sometimes these odd pieces trigger a revolution in our understanding of the world; sometimes they just turn out to be a mistake. The erratic and sometimes violent progress of understanding is troubling to people who live by belief and anchor themselves in certainty, and they will claim that it undermines the credibility of science.

On the contrary, it is the foundation of scientific credibility. The willingness to overturn old beliefs, to accept error, to embrace ferment and change, is what makes reason more credible than religion, which cannot encompass falsification. Reason can progress. Religion can only stagnate and rot in place.

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