“Perfect ability” the requirement of creation, actuality or non-contingency?

Ability is a general requirement of duty which is sometimes considered due to non-ability to fulfill the duties simultaneously and is known as perfect (legal) ability. The question is at what stage of percept (creation, actuality and non-contingency); non-ability to fulfill two duties simultaneously is effective? In this regard, three main doctrines have developed among Usulis: Akhund and Shahid Sadr maintain that legal ability is a requirement for the creation stage, Naeini believes that legal ability is a requirement for the actuality stage, Imam Khomeini, Sheikh Hassan Helli and Mohaghegh Tehrani are of the opinion that legal ability delimits the non-contingency stage and has no effect on the two previous stages. In this paper, after explaining different opinions concerning the above said three doctrines and the problems related to each opinion, the authors have concluded that: first, the rational ability must be altered at the creation stage and this stage must be restricted; since absolute speech as to incapables does not have the excitation and deterrence titles and leads to burdensome duty and absurdity; second, perfect and legal ability i.e. fulfilling two inconsistent duties, is of significance at the non-contingency stage; since in cases of inconsistency, usages of the wise is to consider themselves liable and attempt to find a way to obey.