Dynamics of Opinion

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Sections

• Persuasion
• The Question of Rationality
• Motivated Inference
• Cognitive Dissonance

Summary

• In the context of the decision-theoretic model, there are many different kinds of change in attitude that could cause a change of opinion. Each of these can be thought of as a process by which someone might be persuaded of a particular opinion, although there is no reason to think that real-world processes divide up in exactly the way suggested by the model.

   

• Among these processes, there is one that is clearly rational in the scientific sense and there are others which are clearly scientifically irrational. The clearest example of the latter is that of persuading someone that H by increasing the value bias that they attach to the opinion that H until it overrides whatever other values are operative in that choice of opinion.

   

• For agents cooperating with others in a social environment, there can be expected to be a pressure to have opinions which are coherent over time and which are coherent with one's actions. This pressure counts as a value bias because once a commitment has been made to an opinion, the motivation attaches to subsequent opinions purely in virtue of their content's coherence or incoherence with that original opinion, not because of their epistemic merits.

   

• These considerations point to two processes of inference acting in parallel. One of these works at the level of belief. This would include, for example, belief change that is directly due to perception. The other works at the level of value and action, and works by motivating opinions or actions as a defensive strategy, to make other opinions and actions seem reasonable.

   

• Cognitive dissonance, a much-studied process in which opinions and behaviours change to maintain coherence with each other and with the subject's self-image, shows that motivated inference is a real phenomenon.