 Menzies and Price recognize that, once the notion of causation has been tied in this way to our “personal experience of doing one thing and hence achieving another” (1993: 194), a problem arises concerning unmanipulable causes. To use their own example, what can it mean to say that “the 1989 San Francisco earthquake was caused by friction between continental plates” (1993: 195) if no one has (or given the present state of human capabilities could have) the direct personal experience of bringing about an earthquake by manipulating these plates? Their response to this difficulty is complex, but the central idea is captured in the following passages