The Aronsonian re-interpretation of cognitive dissonance as caused by ideas in conflict with self-image forestalled some obvious applications to philosophical issues lying at the border with psychology. As the action-oriented approach suggests, when Festinger's theory is deepened to pertain to the relations between far-mode and near-mode representations, the similarity between cognitive dissonance and theoretical plausibility becomes almost obvious. Implausibility has the same properties and role as cognitive dissonance. It is an aversive state that that can motivate a change in far-mode beliefs, and the change is toward a form of coherence among beliefs. Rival theories can be rated on a single dimension of plausibility in the same way that they evoke different degrees of dissonance.
The reduction of implausibility to cognitive dissonance bears significant philosophical weight. It denies both Bayesian and coherentist theories of knowledge. The fashionable Bayesian interpretation of implausibility is in terms of degrees of rational belief. A theory is implausible according to the Bayesian School when it possesses a low a priori probability. But we don't thereby scale our beliefs for rationality if we scale beliefs by how much dissonance they cause,. Moreover, to scale them by rationality would require that we have some independent reason for thinking, apart from the comparative cognitive dissonance they arouse, that one theory is more rational than is the other. Scaling our beliefs by the cognitive dissonance they arouse cannot itself be justified on a priori grounds, since dissonance reduction often takes us systematically away from the truth, as in fact is the case in most experimental studies of dissonance. (This helps explain why the identity of dissonance and implausibility hasn't previously been noted.)
Regarding the other negative implication of the dissonance account of implausibility - coherentist theories of knowledge haven't arrived at a clear meaning of "coherence," but coherentist theories emphasize logical and explanatory relations among far-mode ideas (although recent versions have included the role of ideas derived directly from perception). The dissonance theory of implausibility holds that dissonance is aroused by pragmatic incompatibility between near-mode and far-mode cognition. However, we don't seem to be immune to conflicts between our far-mode ideas, although the extent to which we are - the extent of the immunity to far-mode hypocrisy - tends to surprise many of us. The resolution of this problem is that the logical analysis of the relations between far-mode ideas is itself a near-mode activity. (Consider that the practice of mathematics is near-mode, as much as its content is abstract.) We are sensitive to inconsistencies in far-mode ideas only to the extent that we draw upon them in our analytical practices - and to the extent that our own activity involves such practices. Those involved in expounding a doctrine or acting in its terms will be subject to dissonance to the extent that far-mode ideas pragmatically conflict with the performance of their analytical performances.
The dissonance theory of plausibility also bears no the mystery of the conjuring up of theoretical terms. We know that scientific theories go beyond the empirical evidence, as in principle there are infinitely many theories consistent with any set of empirical facts. On the dissonance account of plausibility, theory creation and acceptance is driven by dissonance reduction. Far-more theories promote scientific practices by energizing them. They do this by providing the framework in which scientists work. If work is to be systematic, a framework is necessary, but are the declarative propositions the framework expresses true? Do they have a probability of truth?
Scientific Realist philosophers of science have argued convincingly that theoretical propositions in science often purport to be true, but nobody has come close to providing an account of what it means for an abstract theory to be probable, such that we can inquire regarding the epistemic probability that Newtonian physics was true? The notion that we have rational degrees of belief in theories does accord with some intuitions. Plausibility must allow at least ordinal ranking, since dissonance involves choice between different cognitive states according to their plausibility. This in turn means that the laws of probability apply to ordinal relations. For example, the plausibility of Theory A and Theory B will never be greater than the plausibility of Theory A. But let me suggest that even this is a product of dissonance as shaped by theoretical development, as is shown in studies showing that in many situations we empirically find the conjunction fallacy compelling - that is, plausible.
Sometimes the search for dissonance reduction leads to truth, and sometimes it leads away from truth. Rationality is a limiting case of dissonance reduction, but it's one impossible to specify except from within a psyche subject to the laws of cognitive dissonance. Then this problem: how do we even express the expectation that scientific theories get closer to the truth and religious theories do not? We can say that scientific theories depend on experimental and observational practices and therefore have at least the possibility of resting on actual evidence. We can say scientific theories have greater plausibility than religious theories, these both being judgments that are a product of the law of dissonance. But, counter-intuitively (at least for me), we can't say that scientific theories are more probable than religious theories. It isn't, it's important to notice, that we don't know which is more probable. Rather, the whole notion of probability as applied to theories is misbegotten. That a theory is implausible or plausible is a far-mode conclusion, and far-mode doesn't deal in the relative frequencies modeled by the probability calculus.
A simple example might be clarifying in showing the limits of the concept of probability and its closeness to near-mode experience. During the last presidential election, pollsters arrived at estimates of the probability of winning for each candidate. Pollsters use mainly near-mode reasoning to engineer the best predictive formulas. The pollsters substantially agreed, as you would expect when they each applied similar methodologies, all based on simple extrapolation of the near-mode process of sampling and generalizing to a defined population.
The accuracy of these conclusions, however, depended on certain far-mode assumptions, such as that people taking polls respond honestly. What if this assumption didn't hold? Well, it didn't; Trump won and the main reason the polls got it wrong was (or might have been, if you prefer) that voters polled weren't honest about their preferences. We might ask, what should have been the true probability estimate, given that the pollsters didn't take into account the probability that their model was based on false assumptions. How should they have taken this into account? Probability estimates result from the near-mode operation of fitting observation to a relative frequency model. We can complicate the model to take account of more information, but what we can't do is adjust the probability estimate to take account of the model's own fallibility. (At a deeper level, Bayesian estimates can’t adjust for the probability that the Bayesian methodology itself is invalid—as I contend it is in fact.) If it makes sense to assign a probability to a theory being true, how much belief should be accorded in some idealized rational world, then it should be possible to approximate that probability. Someone can adjust it "intuitively," but my point is that there is nothing appropriate for an intuition to be about. Theoretical plausibility is not probability.
At this point arises a skeptical temptation, for not only is our knowledge not absolute, it isn't even probable. Plausibility can systematically take us away from knowledge. We seem to long for a rationale for doing the rational thing, and such a rationale is supplied when knowledge and rational conduct is represented by Bayesian and decision-theoretic formulas. We see ourselves as free and availed of (mentally) unlimited choice. We are rational because we choose to be, and that entails that the choice itself be rational. But our possibilities aren't unlimited, freely chosen. Our ideas will evolve in accordance with the demands of cognitive dissonance or else moved by receptivity to suggestion. There's no "free will" to seize the initiative, and no direct access to rationality to guide us.