Halpern and Pearl (2005) offer a complex set of conditions that aim to capture the intuition that one should only invoke contingencies "that do not interfere with active causal processes".
An important alternative approach, "pluralism", invokes historical contingency and developmental and genetic constraints, in addition to natural selection, as important causes of the evolution of a trait.
If, for example, the Coalition invoked the Civil Contingencies Act and shut down the main exchanges, some mobile broadband operators would still be able to operate.
Gould noted (1986) that we make this "easy slide" because "we want answers that invoke general laws of nature rather than particular contingencies of history" (Gould 1989) which are not nearly as satisfying to us.
Why is that? A. I'm afraid I'll have to invoke Stephen Jay Gould here, and say there is a strong component of contingency in sexual selection, much more so than in natural selection.
In those countries that have had official racial classifications, individuals' struggles to be re-classified (almost always as a member of a more privileged racial group) are often invoked to highlight the contingency of race, especially at the borders of its categories.
The conservatives invoke freedom of choice.
He didn't even invoke God.
Politicians invoke him as a near-deity.
Yet even he can invoke unity.
Many of the poems invoke religious belief.
