Conclusion
Defeasible reasoning is a key aspect of legal reasoning and
problem-solving. Therefore, theories and logics of defeasible can
greatly contribute to the study of legal argumentation and legal
justification.
Recognising the strength of the connection between defeasibility and the
law does not require abandoning logical rigour. On the contrary, it
favours adopting logical models that precisely match certain important
structures of legal knowledge, certain frequent patterns of legal
reasoning, and of the dialectics of legal interaction. Argument-based
theories of defeasible reasoning provide the most advantageous approach
to address defeasibility in legal contexts.
I have argued that legal theory should addressed defeasibility using a
shared conceptual framework and focus with the other disciplines — in
particular, logic and computing— which have so far addressing
defeasible reasoning. This does not
exclude that the legal theory can provide useful contribution to the
study of defeasibility. In fact, the law provides a rich set of
structures and patterns for defeasible reasoning. Therefore, the
analysis of patterns of defeasibility in the law can contribute not only
to legal theory and (computable) legal logic, but also to the
development of general theories and logical models of defeasibility.