Counterfactual theories of knowledge and the notion of actuality

Abstract

The central question of this article is how to combine counterfactual theories of knowledge with the notion of actuality. It is argued that the straightforward combination of these two elements leads to problems, viz. the problem of collapsing knowledge and the problem of missing knowledge. In other words, there is overgeneration of knowledge and there is undergeneration of knowledge. The combination of these problems cannot be solved by appealing to methods by which beliefs are formed. An alternative solution is put forward. The key is to rethink the closeness relation that is at the heart of counterfactual theories of knowledge.

Anti-Realism and Modal-Epistemic Collapse: Reply to Marton

“…11 The simplified versions can be found in: Heylen (2016Heylen ( , 2020a. One of the simplification is the following: Rabinowicz and Segerberg (1994) define V as a function from sentence letters and pair of worlds to truth values, whereas here V is defined as a function from sentence letters and worlds to truth values.…”

Factive knowability and the problem of possible omniscience

“…De nition 6 (Two-dimensional frames). A two-dimensional frame is a tuple W , R E , R M , with 4 These de nitions are epistemic variations on the de nitions for belief and actuality models in (Heylen, 2016(Heylen, , pp. 1654(Heylen, -1655, which are essentially the models in (Rabinowicz and Segerberg, 1994) with one exception.…”

“…See(Heylen, 2016, p. 1655).6 In(Rabinowicz and Segerberg, 1994, Section 3) the following condition for the weak validity of ϕ → KAϕ is put forward: for every w ∈ W and every proposition π ∈ Π (see 4), if w, w ∈ π , then there exists some ∈ W , such that wR M and, for every w , ∈ W , if , w E , w , then w , w ∈ π . This condition is more general than is needed for the (weak) validity of the scheme ϕ → KAϕ, since there can be propositions that are not expressed by formulas, although every formula expresses a proposition (see footnote 4).…”