As a historian and philosopher of science I have studied many revolutionary scientists, but two particularly stand out because they still generate the most controversy over science and religion today. Welcome Charles Darwin and his recent critic biochemist Michael Behe.
Darwin argued that all life descended from a common ancestor by an unguided process of natural selection (survival of the fittest) acting on random variations that were later identified as DNA mutations. In an 1856 letter Darwin told American botanist Asa Gray: “Either species have been independently created, or they have descended from other species … .” He then confided:
“I assume that species arise like our domestic varieties with much extinction; and then test this hypothesis by comparison with as many general and pretty well-established propositions as I can find made out,—in geographical distribution, geological history, affinities, etc.”
In the struggle to survive (avoid extinction), organisms with the fittest variations tend to live long enough to reproduce and so eventually radically new species arise (assuming there is a source for new beneficial variations that account for major new structures, which is still an unsolved problem). Darwin thought that this process is similar to how humans cultivate new breeds of pigeons and dogs. Breeding dogs is artificial selection (humans guide the process intelligently), but Darwin concluded that new species originate by selection in nature without a guiding intelligence—coining the term “natural selection” for this idea. This revolutionary conception has had a profound effect on science and society.
Darwin’s account of evolution, since updated, is known as neo-Darwinism. It excludes any objectively detectable purpose or intelligent guidance from biological history. Consequently Darwin and his subsequent colleagues have upset many people. This controversy rages today, especially because of a second revolutionary scientist who has upset countless neo-Darwinists. Meet biochemist Michael Behe of Lehigh University.
In his early scientific career Behe saw no problems combining his Catholic faith with neo-Darwinism. In this regard, Behe emulated Darwin’s closest American colleague, Asa Gray (the recipient of Darwin’s letter quoted above), who had promoted what he called “theistic evolution.” Gray attempted harmonizing Darwinian theory with the historic Christianity of the Apostles’ and Nicene Creeds. Later in Behe’s career the scientific shortcomings of neo-Darwinism prompted him to abandon much of his earlier evolutionary perspective.
Here’s the backstory to Behe’s revolutionary discovery. About a half century ago biologists found that some bacteria swim by means of a rotating flagellum, which is a long whip-like propellor connected to a rotary engine that is situated within the cell membrane. About twenty years after this Behe discovered that the bacterial flagellum and many other molecular machines within living cells exhibit a property that he called “irreducible complexity,” and which implied that they could not have originated by an unguided material process like natural selection. Behe sparked a revolution with his book that announced his discovery: “Darwin’s Black Box” (1996), which has sold 300,000 copies.
Regarding the irreducible complexity of the bacterial flagellum Behe has recently said: “If you take away the propeller, if you take away the motor, if you take away the clamps that hold it on to the cell’s membrane, you take away any of a number of different parts, it’s not that the flagellum’s going to spin half as fast as it used to, or a quarter: It’s broken. It doesn’t work at all.” Such a molecular machine is prohibitively unlikely to have evolved by means of a series of accidental mutations that give an organism more and more useful function that is preserved at each step by natural selection.
Behe’s discovery was spurred by Darwin’s challenge in “Origin of Species”: “If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.” Thousands of irreducibly complex molecular machines in living cells seem to break down neo-Darwinism beyond credible belief.
What has become of Behe’s argument in the last few decades? Although some say irreducible complexity has been refuted, here’s a list of essays that show otherwise. In some respects the irreducible complexity argument against neo-Darwinism and for intelligent design is more robust than ever before. Experience this compelling story in the documentary Revolutionary: Michael Behe and the Mystery of Molecular Machines—now available for free.
A prominent intellectual has recently recognized Behe as a revolutionary scientist worthy of respect. The atheist philosopher Thomas Nagel announced in his 2012 book “Mind and Cosmos” that “the materialist neo-Darwinian conception of nature is almost certainly false.” While Nagel is not an advocate of the alternative scientific theory known as intelligent design, Nagel argues that intelligent design theorists such as Behe “do not deserve the scorn with which they are commonly met.” He grants the respectability of Behe’s scientific arguments “against the likelihood that the origin of life and its evolutionary history can be fully explained by physics and chemistry.” Nagel concludes that the “problems that these iconoclasts pose for the orthodox scientific consensus should be taken seriously.” Upsetting the “orthodox scientific consensus” is what scientific revolutionaries do, as Charles Darwin and Michael Behe illustrate so well.
Michael N. Keas is Adjunct Professor of the History and Philosophy of Science at Biola University and a Fellow of the Discovery Institute’s Center for Science & Culture.