Consideration of motives brings up the matter of free will. I had better say once, that my project of taking animal comparisons seriously does not in… - Mary Midgley

The point cannot be just survival, nor even survival in numbers. Survival is just as well achieved by much less ambitions creatures which go in for sheer number. (In fact a cost-benefit-conscious gene that really understood its business would, no doubt, have remained on board something like the amoeba; it will probably be amoung the last to go.) Nor is it survival-as-society, since many animals achieve this despite a lot of bickering.

We must face unconsidered possibilities and ask ourselves alarming questions–for instance, must we perhaps let the self-destroyer go if he really wants to? Trying to answer this by collecting information about our own neurones would be no more use than doing it, like the Roman augur, by inspecting the entrails of a goat.

Many people fail to grasp this point, apparently because they think of "scientific" evidence as only that produced in laboratories by controlled experiments. This leads them to treat field studies, however careful, thorough and well-documented, as "anecdotal"--mere preparation for the real thing, therefore properly ignored till it bears fruit entitled to be considered by learned persons. This attitude was much like that of cavalry generals in the First World War, waiting patiently for the infantry to clear the ground so that they could make the dashing charges that alone they thought entitled the name of warfare. Because these creatures are complex, only a tiny fraction of important truths about them can ever be seen in laboratories of expressed in control experiments. The same, of course, is true of the human race.