Via Tbogg, the great H. Allen Orr has a great article about Bobo’s latest book. Read the whole thing, but this is a good explanation of why I reach for my revolver whenever I hear a non-scientist say “nonlinear”:
Brooks claims repeatedly, for instance, that the unconscious—that most important part of the mind—corresponds to a murky domain of the unpredictable, the irregular, and the nonlinear. Indeed rationality, he announces, can’t acknowledge the importance of the unconscious because “once it dips its foot in that dark and bottomless current, all hope of regularity and predictability is gone.” But none of this follows. A process can be both perfectly unconscious and perfectly predictable. You are not conscious, for example, of how you use visual information from one eye to fill in for the blind spot from the other eye but I can confidently predict that you are doing so now.
Similarly, Brooks’s talk of nonlinearity is a red flag warning of scientific naiveté. “Nonlinear” has a precise mathematical meaning: the relation between two variables when plotted on a graph doesn’t look like a straight line. However, in Brooks’s hands, it means something that’s fuzzy or “cloudlike.” But there’s nothing fuzzy or cloudlike about, say, the change in the frequency of a gene under the action of natural selection; yet the relevant dynamics are nonlinear.
Update. A quote from the book that is highlighted in the article:
Later in their relationship, Rob and Julia would taste each other’s saliva and then collect genetic information.