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In science, the game plan aims for increments.

Byline: GUEST VIEWPOINT By Paul Engelking

In his Sept. 10 column, Matt Ginsberg set for himself the job of comparing the logic of beliefs based on science to that of beliefs based solely on faith. While pointing out their commonalities, he did not emphasize the point of their differences. Some readers were unsatisfied, responding like fans whose football team had punted on first down. Let's see if we can carry the ball a bit further in trying to understand how the logic of science works.

In a folksy graduation address that has become famous, "Cargo Cult Science," a former instructor of mine, physicist Richard Feynman, explained, "The first principle is that you must not fool yourself - and you are the easiest person to fool."

So, how do we try to not fool ourselves? Well, maybe we can just try to think logically.

Logic is beautifully unspoiled in the abstract, but to apply it to the world you have to give it some data. And if you feed it some errant data, it will happily spit out some errant deductions. Garbage in; garbage out. We must be absolutely rigorous in sanitizing our data at input, making sure there is nothing wrong with our assumptions.

Validating data is easier said than done, and seldom can it be done with certainty. Worse, our own logic often sacks us behind the line of scrimmage. There are some things that we would want to be able to assume to make logical deductions but - even our own logic tells us - they can't be directly observed.

To see how this problem might arise, you might have been bothered in Logic 101 by this simple syllogism of Aristotle's. From two propositions - 1) Plato is a man and 2) all men are mortal - Aristotle would deduce that 3) Plato is mortal. Aristotle might easily verify by observation the first proposition, since he knew Plato personally. But the second proposition, that all men are mortal, would have been logically impossible for Aristotle to directly observe. He couldn't possibly be able to verify this fact for all men. Aristotle, for one, would have to be alive to make this observation!

Requiring that all our assumptions be verified by direct observations is too strict a rule: it would stop all play. But might we check our assumptions without direct observation?

Here science tries an end run around the problem. It makes a lateral pass: it runs the logic backwards. If some of our assumptions are garbage, we can expect that some of our logical deductions drawn from them also will be garbage. If any of our logical deductions don't match our observations, we know something is wrong in our assumptions.

In an amici curiae brief (Nicolaas Bloembergen, et al.) filed in the 1993 U.S. Supreme Court case Daubert vs. Merrell-Dow Pharmaceuticals, 18 well-respected scientists outlined this point in what they thought it means to be "scientific." This has become the basis for the rules of evidence for deciding in federal court what expert evidence is "scientific."

Taking a cue from legal procedure, I would propose that what distinguishes science from other modes of thought is not its logic, but its particular rules of evidence. First, science allows the evidence of direct observations (of course, scientists are responsible for making "good" observations).

But insisting that all our assumptions be validated only by direct observation would leave us in a permanent state of omphaloskepsis.

So secondly, science tries to circumvent this by also allowing (tentative) assumptions of some things we can't directly observe, but only if we can subject their logical consequences to tests that might potentially falsify them by revealing inconsistencies with those things that we can observe.

Of course, scientists have the responsibility to design these tests, and perform them. And there are other scientists, acting as referees, ready to blow the whistle if they don't. The more, and the more rigorous, tests that our theories pass, the less tentatively we hold their assumptions. It is then human nature to score them higher on our individual, and collective, "belief-o-meters."

Science may not be able to reach the goal of absolute certainty, but it tries to run the ball of credibility down field incrementally. Science knows that if it chooses a bad play, it can expect to get its assumptions kicked.

I don't know how thought-provoking this essay may have been, but I hope that I left team science on the field with at least a game plan and a chance to play another down!

Paul Engelking of Lowell, a professor of chemistry at the University of Oregon, has testified in court as a scientific expert, and has consulted with the state Department of Justice on the admissibility of scientific evidence.
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Title Annotation:Guest Viewpoint
Publication:The Register-Guard (Eugene, OR)
Date:Sep 29, 2014
Words:789
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