A Scientist Thinks Outside the Box: The Null Hypothesis

I am trained as a research scientist, with a doctorate in Biology from Cornell University and a long list of publications in refereed journals in my specialty, the classification of fungi. I do not wave these credentials in order to claim expertise in any or all aspects of science, but rather to establish that I am accustomed to modern Western habits of scientific thought and capable of bringing them to bear in other aspects of human intellectual activity.

A key aspect of any scientific inquiry is the null hypothesis: that is, the mirror image of the model/generalization, the value of which the research scientist is attempting to demonstrate, either through actual experiment or through systematic observation in systems such as the Solar System that do not lend themselves to experimental manipulation. Rigorous scientific proof requires demonstrating that the null hypothesis is extremely unlikely.

A well-designed experiment ought to simultaneously produce evidence concerning a hypothesis and its alternative, and be objective in data collection. Poor science that translates into poor policy decisions results when an investigator selectively collects and considers data likely to support the original hypothesis, ignoring evidence to the contrary. That political ideologies and the corporate bottom line both influence what questions scientists explore, how they conduct research, and how the results are disseminated, is scarcely to be doubted.

Having seen firsthand what goes into the sausage that the media markets to the public as proven scientific fact, I entertain a healthy skepticism when some bit of science becomes the object of evangelical zeal, and its proponents demonize all opposition, ridiculing the null hypothesis as unworthy of a second thought.

This skepticism was recently activated by a post on a social networking site concerning a recent law passed in Tennessee, which states, among other things, “”The state board of education, public elementary and secondary school governing authorities, directors of schools, school system administrators, and public elementary and secondary school principals and administrators shall endeavor to create an environment within public elementary and secondary schools that encourages students to…respond appropriately and respectfully to differences of opinion about controversial issues.” Two issues, specifically alluded to, were the chemical origins of life and global warming, and the reposted feed characterized this as a corporate conspiracy to require the teaching of climate change denial in Tennessee schools.

Climate change is real. That global temperatures have been rising in recent decades is an incontrovertible fact. The correlation between temperature rise and increased concentrations of greenhouse gases, whose principal source is burning fossil fuels, is also not controversial. However, the cry of climate change is being used to sell products and policies that are not necessarily in the public interest and some of the charge of “climate change denial” targets legitimate questions. Recently a political candidate in my home town tried to convince me that because I was concerned about global warming (which I am) I should naturally support not only public transportation (which in general I do) but a specific costly project that no-one has demonstrated will either improve the overall convenience and attractiveness of the local bus system or result in net energy savings.

Failing to respond appropriately and respectfully to differences of opinions about controversial scientific issues is bad pedagogy, and presuming that no legitimate controversy can exist, simply because the preponderance of evidence now at our disposal favors a particular theory, is bad science. How many theories, espoused within the last hundred years with as much fervor as those mentioned in the Tennessee statute, are now wholly or in part discredited? No one would now, for example, presume to teach science from A History of the Warfare of Science with Theology in Christendom by Andrew Dickson White (1898) – though I have seen it quoted as a justification for allowing attacks on religion in school classrooms. White’s fellow faculty member, zoology professor Burt Green Wilder, assembled a collection of over 600 pickled human brains in the belief that investigation of the minutiae of their construction could be correlated with all manner of individual character traits. A fair chunk of what I learned in high school biology in 1962 is now dated and doubted.

Without understanding the essential difference between a theory (however robust and well-demonstrated), which is always open to question, and a well-documented concrete data point, a person is never going to really understand the scientific method. 


Photo Credit

American Phrenology Journal – Public Domain


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