An event was unexpected for both parties means that both of them did not believe at the contract making that the event is possible. To demonstrate this, the court needs to reconstruct what parties believed at the time of making contract. Formally, it means that two argumentation modules representing respectively belief bases of two parties at contract making need to be constructed.

In general, argumentation modules that need to be constructed for reasoning with a legal doctrine constitute the context under the doctrine. The context under the doctrine of impossibility consists of :

1. •ε : an unexpected event
   

1. •BO, BE:  argumentation modules representing the beliefs of contractor CO (or seller, provider)and contractee CE (or buyer, customer) at contract making,
   

1. •KO, KE: argumentation modules representing the professional (or expertise) knowledge of CO and contractee CE  are expected to know at contract making.
   

1. •CK: an argumentation module representing the common knowledge.
   

1. •Cost: a function specifying the cost of possible actions the contract parties could carry out to prevent ε, or mitigate its consequences
   

A main module representing the doctrine itself should then combine these modules to construct legal arguments. Legal arguments following the doctrine of impossibility are graphically depicted below.  Note that we make use of two argumentation semantics, namely credulous and skeptical, respectively represented two consequence relations ⊢cr and ⊢sk, to model the risk attitudes of contract parties. Intuitive, a relationship BX ⊢cr  ε between the belief base BX of a party CX and an future event ε says that CX believes that ε is possible. In contrast, BX ⊢sk  ε says that CX fully believes in ε.

For the purpose of automatically generating arguments, MoDiSo represents both legal doctrines and modules of contexts by assumption-based argumentation frameworks. Readers are referred to our publications for details.

Rescind(CO,  Γ)

Impossibility(Γ)

¬ RiskAllocatedTo(CO, Γ)

ViolateBA(Γ)

UnExpected(ε)

neither  BO ⊢cr  ε

nor        BE ⊢cr  ε

CK ⊢sk E ⊏ ε

CK ∪ {ε}   ⊢sk  ¬m

CK ∪ {¬m}   ⊢sk  ¬τ

RiskAllocatedTo(CO, Γ)

Taylor v Caldwell

Click here to view the doctrine applied to Taylor v Caldwell

FDA v GIS

Click here to view the doctrine applied to FDA  v GIS

PreOrMiti(CO, ε)

KO ⊢cr    ε

CK ⊢sk ReasonableAction(CO, α)

KO ∪ {α}   ⊢cr  ¬ ε

or

KO ∪ {α, ε}   ⊢cr  m

Contractor CO

Contractee CE

Expected(ε)

BO ⊢cr ε

Expected(ε)

BE ⊢cr ε

Contractee CE

Doctrine of Impossibility<1,2,3,4>