 Some, if not most, of this confusion is a result of a very important but neglected duality in the meaning of “adaptation” (in spite of useful discussions in Brandon 1978, Burian 1983, Krimbas 1984, Sober 1984). Sometimes “adaptation” is taken to signify any trait at all that is a direct result of a selection process at that level. In this view, any trait that arises directly from a selection process is claimed to be, by definition, an adaptation (e.g., Sober 1984; Brandon 1985, 1990; Arnold &amp; Fristrup 1982). Sometimes, on the other hand, the term “adaptation” is reserved for traits that are “good for” their owners, that is, those that provide a “better fit” with the environment, and that intuitively satisfy some notion of “good  engineering.”[8]  These two meanings of adaptation, the selection-product and engineering definitions respectively, are distinct, and in some cases, incompatible.