Contextual Abductive Reasoning with Side-Effects
  The belief bias effect is a phenomenon which occurs when we think that we
judge an argument based on our reasoning, but are actually influenced by our
beliefs and prior knowledge. Evans, Barston and Pollard carried out a
psychological syllogistic reasoning task to prove this effect. Participants
were asked whether they would accept or reject a given syllogism. We discuss
one specific case which is commonly assumed to be believable but which is
actually not logically valid. By introducing abnormalities, abduction and
background knowledge, we adequately model this case under the weak completion
semantics. Our formalization reveals new questions about possible extensions in
abductive reasoning. For instance, observations and their explanations might
include some relevant prior abductive contextual information concerning some
side-effect or leading to a contestable or refutable side-effect. A weaker
notion indicates the support of some relevant consequences by a prior abductive
context. Yet another definition describes jointly supported relevant
consequences, which captures the idea of two observations containing mutually
supportive side-effects. Though motivated with and exemplified by the running
psychology application, the various new general abductive context definitions
are introduced here and given a declarative semantics for the first time, and
have a much wider scope of application. Inspection points, a concept introduced
by Pereira and Pinto, allows us to express these definitions syntactically and
intertwine them into an operational semantics.
