 Lewis’s dissatisfaction with his own attempts to deal with the problem of late preemption, as well as his theory’s inability to deal with ‘trumping preemption’ (Schaffer 2000a), led to the development of his 2000 theory. A further problem relating to preemption that arises for chancy causation – which the 2000 theory does not address – is discussed in  §5.4  below.