What is Meant by Proof

Proof is a word associated with science that is commonly misapplied by non-scientists. For example, although media reports might say that scientists have proof of the relationships between birds and dinosaurs, a reporter actually would be more accurate in saying scientists have documented yet more convincing evidence supporting the relationships between birds and dinosaurs (Chapters 8, 9, and 15). Scientific methods do not deal with absolute proof of a hypothesis or even a theory; "proof" is a completely accepted premise that is often erroneously syn-onymized with "truth," although the latter is closer in meaning to the previously-defined term "fact." Proof implies unchangeable conclusions in idealized situations, such as those offered in mathematical proofs of geometric relationships. In other words, mathematicians seek to prove their ideas, whereas scientists attempt to test and disprove them.

What scientific methods can do is disprove (falsify) hypotheses or theories. Thus, proof does not enter scientific discussion because scientists do not expect to find a perfect explanation for what they have observed. Nevertheless, they hope in the future to approach a more correct explanation than what they have now. This attitude requires typically more observations (data collection), analysis, testing, and peer review. Consequently, a scientist's job is never done because science, by its very nature, is always changing, self-correcting, and being continually refined by new discoveries, never achieving proof. Paleontology is a wonderful example of this type of change. As poor as the fossil record might seem in comparison to all of the life that has lived on the Earth during its 4.6-billion-year existence, it improves every day as yet more new fossils are found, described, and interpreted. In fact, as more fossils are found, they provide a framework whereby paleontologists become increasingly less surprised by new fossil finds.

An example of how the concept of proof can be superseded by scientific methods is seen in the practice of law. If a trial results in a guilty verdict, the jury is making this decision on the basis of asking themselves if the defendant is guilty "beyond a reasonable doubt." This ruling is typically made on the basis of the evidence presented in the trial, so it approximates a scientific methodology and may involve the testimony of expert witnesses, some of whom might be professional scientists. The now-common application of DNA testing to people convicted of crimes, however, sometimes years after they were convicted, has the potential to show with 99% probability that another person committed the crime. Thus, the new results exonerate (falsify) the jury verdict, and the prosecuting attorney's proof is rendered invalid.

So a challenge to all readers of this book, in their applications of scientific methods, is to ask:

1 which statements about dinosaurs presented in this book are based on hypotheses, and

2 which are based on opinions.

A suggested procedure for this line of inquiry is to ask the following questions:

■ What factual evidence supports the statement?

■ Is the statement testable?

■ Is the testing repeatable and independently verifiable?

■ Did the idea expressed in the statement undergo peer review in the scientific literature or other scientific forums?

■ Can the statement be used to make predictions?

■ Can the statement be proved false?

A cautionary note in this respect is to beware of people who claim to be scientists and say such things as "But I have proof!" This person is most likely not a scientist because most scientists are very careful, after years of experience and conditioning by their mentors and peers, to use this word sparingly in their scientific vocabulary. Much of science consists of mostly friendly argumentation prompted by curiosity that rarely ends with the final acceptance of a hypothesis, because hypotheses are, by definition, conditional. Even a well-supported hypothesis or theory should provoke more questions, rather than a single, definite answer.

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