We can never compare model with reality (Chapter 9). In a crux, though, we may compare models, and switch from one to another. Thomas Kuhn emphasizes this point with reference to the history of science:
… once it has achieved the status of a paradigm, a scientific theory is declared invalid only if an alternate candidate is available to take its place. No process yet disclosed by the historical study of scientific development at all resembles the methodological stereotype of falsification by direct comparison with nature.… The decision to reject one paradigm is always simultaneously the decision to accept another, and the judgment leading to that decision involves the comparison of both paradigms with nature and with each other.
— Kuhn (1969, 77)
A paradigm or theory can be ‘compared with nature’ only in the sense that the success of its applications can be repeatedly assessed by inductive reasoning based on many observations. Such a ‘comparison’ is indirect, while the comparison of paradigms with each other can be made directly when they are represented iconically.
Likewise, on the individual level, we cannot compare the memory of an event with the event’s occurrence in real time.
… memory is a system property reflecting the effects of context and the associations of the various degenerate circuits capable of yielding a similar output. Thus, each event of memory is dynamic and context-sensitive—it yields a repetition of a mental or physical act that is similar but not identical to previous acts. It is recategorical: it does not replicate an original experience exactly. There is no reason to assume that such a memory is representational in the sense that it stores a static registered code for some act. Instead, it is more fruitfully looked on as a property of degenerate nonlinear interactions in a multidimensional network of neuronal groups. Such interactions allow a non-identical ‘reliving’ of a set of prior acts and events, yet there is often the illusion that one is recalling an event exactly as it happened.
— Edelman (2004, 52)
But such a memory is representational in the semiotic sense; it is even a paradigm of semiosis, as Peirce said: ‘The type of a sign is memory, which takes up the deliverance of past memory and delivers a portion of it to future memory.’