Rational is related to Reasonable. Reasonable is related to Valid. 
Find is a type of Reason. Reason is related to Emotion. Willingness is a type of Emotion. Willingness is a synonym of Consent. 
Rational <--RelatedTo--> Reasonable <--RelatedTo--> Valid 
Find --IsA--> Reason <--RelatedTo--> Emotion <--IsA-- Willingness <--Synonym--> Consent 