  The simple symbol shift dynamics in  §4.5  had a finite seed, which allowed for chance without randomness. Yet there seem to be physical situations in which a symbol shift dynamics is an accurate way of representing the physical processes at work. One simple example might be a stretch and fold dynamics, of the kind common in chaos theory (Smith 1998: §4.2). The classic example is the baker’s transformation (Earman 1986: 167–8; Ekeland 1988: 50–9). We take a system the state of which at any one time is characterised by a point \((p, q)\) in the real unit square. We specify the evolution of this system over time as follows, letting \(\phi\) be the function governing the discrete evolution of the system over time (i.e., \(s_{t + 1} = \phi(s_t))\):