Separating Science from Belief
Let’s review the scientific method. Very simply (and somewhat naively), the scientific method is a program for understanding the natural world. It comprises four main steps. In practice these steps follow more of a logical order than a chronological one:
1. Make observations.
2. Form a testable, unifying hypothesis to explain these observations.
3. Make predictions from the hypothesis.
4. Search for confirmations of the predictions
If the predictions are contradicted by careful observation, go back to step (2).
Because scientists are constantly making new observations and testing via those observations, the four "steps" are actually practiced concurrently.
New observations, although they were not originally predicted, should be explicable by the hypothesis.
New information, especially details of some process previously not understood, can impose new limits on the original hypothesis.
Therefore, new information, in combination with an old hypothesis, frequently leads to novel predictions that can be tested further.
Examination of the scientific method reveals that science involves much more than naive observation.
Research that only involves simple observation, repetition, and measurement is not sufficient to count as science. They are merely part of the process of making observations (#1 in the steps outlined above).
Astrologers, wiccans, alchemists, and shamans all observe, repeat, and measure—but they do not practice science. Clearly, what distinguishes science is the way in which observations are interpreted, tested, and used.
The Testable Hypothesis
The defining characteristic of science is the concept of the testable hypothesis.
A testable hypothesis must make predictions that can be validated by independent observers.
By "testable," we mean the predictions must include examples of what should be observed if the hypothesis is true and of what should not be observed if the hypothesis is true.
"Testability" is not an either-or concept; some hypotheses are more testable than others. Contrary to some anti-evolutionist claims, not all hypotheses are equally valid scientific "interpretations" of the evidence.
Based on the scientific method, a hypothesis that simply and elegantly explains the observed facts, that predicts many previously unobserved phenomena, and that withstands many potential falsifications is considered a valid and useful hypothesis.
What may sound surprising, and that bears some thought, is that a hypothesis that can explain all possible observations is not testable and so is not scientific.
Creationists and the believers in "intelligent design" fail scientifically because they explain all observations as an act of God, but they cannot test these theories nor can they make specific predictions.
Scientific theories or hypotheses lead to predictions.
For instance, the belief that the entire universe is actually an elaborate figment of your imagination is not a scientific hypothesis. No further observations could conflict with the idea, since all observations may always be explained away as simply another detailed creation of your imagination.
Many other extreme examples can be thought of, such as the hypothesis that the universe suddenly came into existence in toto five minutes ago, with even our memories of "earlier" events created five minutes ago, as well.
Degrees of Testability: Hypotheses, Theories, Facts
"Testability" is not an either-or concept; some hypotheses are more testable than others. Contrary to some anti-evolutionist claims, not all hypotheses are equally valid scientific "interpretations" of the evidence.
In scientific practice, a superior and well-supported hypothesis will be regarded as a theory. A theory that has withstood the test of time and the collection of new data is about as close as we can get to a scientific fact.
An example is the notion of a heliocentric solar system (in which the planets revolve around the Sun). At one time it was a mere hypothesis. Although it is still formally just a well-supported theory, validated by many independent lines of evidence, it is now widely regarded as scientific "fact."
Nobody has ever directly observed an electron, radiowaves, or the earth circling the Sun, yet these are all scientific facts. As Stephen J. Gould has said, a scientific fact is not "absolute certainty," but simply a theory that has been "confirmed to such a degree that it would be perverse to withhold provisional consent."
Testing Involves a Totality of Evidence and Statistics
The validity of a hypothesis does not stand or fall based on just a few confirmations or contradictions, but on the totality of the evidence. Often, data that initially may seem to be inconsistent with a theory will in fact lead to new important predictions. The history of Newtonian physics gives a clear example.
The observation of the anomalous (that is, contrary to expectation, or what we might call "strange") movement of the planet Uranus was initially considered a potential falsification of Newton's new theory of gravity. However, by claiming the existence of an unseen planet, the anomaly could be explained within Newton's theory.
Claiming the existence of a new, unseen planet might be considered hedging if there were no independent way to detect if a new planet actually existed. Nevertheless, when technology in the field of astronomy had advanced enough to reliably test the new prediction, the previously unseen and unknown planet Neptune was found. And its motion was completely explicable (predictable) through the application of Newton's Law of gravitation.
The lesson to be learned is that alternate explanations for "anomalies" should be treated like any other hypotheses: they should be weighed, tested, and either ruled out or confirmed. But a hypothesis should not be considered falsified until thorough testing has produced multiple lines of positive evidence indicating that the hypothesis is truly inconsistent with the empirical data.
One of the most famous examples of the conflict between science and faith is the trial of John Scopes in 1925 (often referred to as The Monkey Trial). We’ll leave that for the next posting.
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