Verificationism has been a hallmark of logical empiricism. According to this principle, a sentence is insignificant in a certain sense if its truth value cannot be determined. Although logical empiricists strove for decades to develop an adequate principle of verification, they failed to resolve its problems. This led to a general abandonment of the verificationist project in the early 1960s. In the last 50 years, this view has received tremendously bad press. Today it is mostly regarded as an outdated historical (...) concept. Theories that have evolved since the abandonment of verificationism can, however, help overcome some of its key problems. More specifically, an adequate criterion of significance can be derived from a combination of modern theories of justification and belief revision, along with a formal semantics for counterfactuals. In view of these potential improvements, the abandonment of verificationism appears premature. Half a century following its decline, it might be about time to revisit this disreputable view. The author argues in favor of a weak form of verificationism. This approach could be referred to as minimal verificationism, as it involves a weakening of traditional verificationist principles in various respects while maintaining their core idea. (shrink)

The AGM success postulates for belief expansions and revisions have been widely criticized. This has resulted in the development of a number of non-prioritized belief change theories that violate these postulates. It is shown that we must also discard the monotony postulate for belief expansions if we abandon the success postulates. Non-prioritized belief change theories should instead fulfill a weaker postulate, which we call Conditional Monotony.

Belief revision theories aim to model the dynamics of epistemic states. Besides beliefs, epistemic states comprise most importantly justificational structures. Typically, belief revision theories, however, model the dynamics of beliefs while neglecting justificational structures over and above logical relations. Despite some awareness that this approach is problematic, how devastating the consequences of this neglect are has not yet been fully grasped. In this paper, I argue that taking justificational structures into account could solve four well-known problems of belief revision.

Although the AGM theory established a paradigm for the theory of belief revision, which is generally regarded as a kind of standard in the field, it is also frequently criticized as inadequate because it neglects justificational structures. Other theories of belief revision are similarly remiss in this regard. So far, little has been done to address this shortcoming. This paper aims to fill this gap. Following a critical analysis of the AGM theory, a justification operator is introduced as a formal (...) means to incorporate justificational structures into a belief revision theory. An AGM style belief revision theory is proposed that is based on such a justification operator. The theory is presented in an axiomatic form. Representation theorems link the axioms with constructive belief change mechanisms. The proposed theory addresses the problems of the AGM theory and similar approaches that neglect justificational structures. (shrink)