Preface



    Classical reasoning is not flexible enough when directly applied to the formalization
of certain nuances of human quotidian decision making. These involve different kinds of
reasoning such as reasoning with uncertainty, exceptions, similarity, vagueness, incomplete
or contradictory information and many others.
   It turns out that everyday reasoning usually shows the two intertwined aspects below:
Ampliative aspect: augmenting the underlying reasoning by allowing more conclusions.
In practical contexts, this amounts to the ability to make inferences that venture beyond
the scope of the premises, somehow in an unsound but justifiable way. Prominent examples
are (i) default reasoning: jumping to conclusions deemed as plausible ‘by default’, i.e., in
the absence of information to the contrary, like applying negation as failure or adopting
the closed-world assumption, and (ii) inductive and abductive reasoning: taking chances
in drawing conclusions that implicitly call for further scrutiny or tests by empirical ob-
servations, like in making inductive hypothesis in scientific theories or finding abductive
explanations in forensics.
Defeasible aspect: curtailing the underlying reasoning by either disregarding or disallow-
ing some conclusions that somehow ought not to be sanctioned. In practice, this amounts
to the ability to backtrack one’s conclusions or to admit exceptions in reasoning. Some
examples of this are (i) retractive reasoning: withdrawing conclusions that have already
been derived, like in belief contraction or in negotiation, and (ii) preemptive reasoning:
preventing or blocking the inference of some conclusions by disallowing their derivation in
the first place, like in dealing with exceptional cases in multiple inheritance networks and
in regulatory systems.
    Several efforts have been put into the study and definition of formalisms within which
the aforementioned aspects of everyday reasoning could adequately be captured at differ-
ent levels. Despite the progress that has been achieved, a large avenue remains open for
exploration. Indeed, the literature on nonmonotonic reasoning has focused almost exclu-
sively on defeasibility of argument forms; belief revision paradigms are restricted to an
underlying classical (Tarskian) consequence relation, and even if some of the issues related
to uncertainty in reasoning have been studied using probabilistic approaches and statisti-
cal methods, their integration with qualitative frameworks remain a challenge. Moreover,
well-established approaches are largely based on propositional languages or haunted by the
undecidability of full first-order logic. Modern applications require formalisms with a good
balance between expressive power and computational complexity.
     DARe aims at bringing together researchers and practitioners from core areas of ar-
tificial intelligence, cognitive sciences, philosophy and related disciplines to discuss the
defeasible and ampliative aspects of reasoning in a multi-disciplinary forum. The goal of
the workshop is to present latest research developments, to discuss current directions in
the field, and to collect first-hand feedback from the community.
    Submissions to DARe 2014 were peer-reviewed by at least two members of the Program
Committee. The accepted papers, bound in these Workshop Notes were carefully selected
based on their quality, relevance to the workshop topic, and their potential to bring forward
interesting ideas to be discussed at the workshop.
    Thanks to the invaluable and much appreciated contributions of the authors and the
Programme Committee, DARe 2014 provides participants with an opportunity to position
their contributions with respect to one another. Hopefully, this will encourage further cross-
pollination and set out the constitution of a truly interdisciplinary research-community
around the different aspects and approaches to defeasible and ampliative reasoning.



                         (Luxembourg, Pretoria, Rio de Janeiro, Toulouse – August 2014)
      Richard Booth, Giovanni Casini, Szymon Klarman, Gilles Richard, Ivan Varzinczak