As illustrated by the preceding example, paradigms perform the invaluable service of rendering "the known universe" intelligible. As a result, paradigms also provide a structure within which knowledge can be organized cohesively. Nevertheless, a paradigm's Achilles heel lies in the truism that the parameters of the known universe are constantly in flux: curious humans incessantly generate novel observations about a constantly changing universe. Again, popular as geocentrism once may have been, an overload of anomalous heavenly phenomena (e.g., comets, retrograde motion, Jupiter's moons, etc.) inevitably doomed the paradigm. When paradigms are overwhelmed by a critical mass of anomalies they enter a phase that Kuhn described as a crisis. Roughly speaking, paradigm crisis is the scientific equivalent of a skipper's signal to abandon ship. Having sprung more epistemological leaks than its adherents can hope to plug, a paradigm in crisis forces its supporters to make a fateful choice: either to jump ship or remain aboard the foundering vessel until the bitter end.
Paradigm crisis is a precursor to full scale scientific revolution. According to Kuhn, a scientific revolution comprises a transition through which scientists replace an outmoded paradigm with a new one (e.g., from young-earth creationism, to Darwinian evolution). Generally speaking, the new paradigm has the advantage of being, so to speak, a more seaworthy vessel, i.e., it resolves many of the anomalies that sank its predecessor. Therefore, for a period of time, the new paradigm can confidently go about the process of enlisting recruits and navigating rough scientific seas; that is, until the process inexorably repeats itself and the updated paradigm is beset by its own set of leaks.
Kuhn developed this non-linear view of scientific knowledge accumulation based upon his examination of the history of science. In particular, Kuhn noted that scientific paradigms often incorporate foundational assumptions that are antithetical to the leading assumptions of succeeding paradigms, e.g., one cannot maintain an honest intellectual commitment to creationism and evolutionary theory without suffering from multiple personality disorder. It requires the intervention of an historical revisionist to invent a smooth, linear transition from one scientific paradigm to the next. As such, the fact that successive paradigms tend to be incommensurable suggests that there is no essential consistency (i.e., no inherent "truth") in scientific progress. That is, if scientific truth is linked to the assumptions upon which scientific paradigms are founded and, in turn, if scientific paradigms are disposable, then even in the most rigorous scientific endeavors truth must be only a provisional, transitory standard. In a world of paradigm shifts, truth would appear to be a chimera.
In keeping with this attitude, copious aspersions have been cast on scientific truth (McGettigan, 2011a). Nevertheless, far from indicating an absence of truth, I argue that (r)evolutionary innovations in the structure of scientific knowledge are not an indication of the truth's scarcity. Contrarily, I contend that the process of undergoing paradigm shifts represents the most definitive indication of the scientific commitment to Truth. Incommensurable as emergent scientific paradigms may appear, nevertheless, in every case there remain essential evolutionary linkages between historic, existing and succeeding paradigms. Indeed, the epistemological relationship between distinct scientific paradigms is similar, in a metaphorical sense, to the biological speciation process. Just as biological evolution propagates species that appear to have little or no connection to their predecessors (e.g., marine mammals v. their ancient terrestrial forbears), so too do scientific paradigms spawn new epistemologies that appear to lack clear genetic linkages (e.g., geocentrism vs. the Big Bang). Though one may have to search to find it, a logical (and, in the case of the philosophy of science, a social) connection exists between evolutionarily-distinct constructs. Crucially, for the purposes of understanding the production of truth, it is essential to recognize the manner in which new paradigms, unique as they may be in many respects, generally speciate from within the context and tradition of established paradigms.
In spite of the apparent epistemological discontinuity between paradigms, I assert that the production of scientific truth takes place through a process of redefining reality (McGettigan 1999, 2011). In other words, truth is not contained within any particular paradigm, but rather truth guides and enables the process of transitioning from outmoded to new-and-improved paradigms. Also, truth-making never has been and never will be a linear process. Instead, the production of truth is associated with a process whereby creative human agents, upon encountering an abundance of environmentally disruptive phenomena (i.e., epistemological anomalies), often develop wildly inventive, but nonetheless adaptive solutions to resolve the epistemological anomalies that they encounter (for example, Einstein's legendary modifications to Newton's mechanical universe).
As is the case with evolving organisms, emergent paradigms may appear to be constructs of an entirely new order. Nevertheless, outlandish as they may seem, emergent paradigms maintain demonstrable linkages with their ancestors (e.g., heliocentrism is a very different animal, but still retains obvious affinities with geocentrism). The difference is that emergent paradigms have been modified through a process of redefining reality to transcend the shortcomings of established paradigms and, thereby, achieve a better fit with prevailing environmental conditions (i.e., paradigms evolve through an extensive reimagination process that is intended to reduce anomalies and, thereby, generate a more comprehensive grasp of the ever changing known universe). Thus, I argue that paradigmatic evolution is a process that, while spawning epistemological systems of unique and unusual design, is nevertheless sustained by a consistent standard of truth.