The rule of "simple truth" is one of the famous rules that has been highly regarded in the transcendent wisdom of Sadra. And has been used to prove important claims . like proving the objectivity of the essential attributes of God with the essence of God and proving God's knowledge of beings before creating possibilities.
The argument that Sadr al-Muta'allehin makes to prove this rule is that if the simple truth does not have all beings, then her truth is composed of having something and not having and this is against his simplicity.
According to the author, from a mystical point of view, this rule has problems both in terms of the principle of the claim, in terms of its argument, and in terms of the consequences that follow from it because being has no multiplicity and the reason given to prove the claim is violated. And the truth of God has no attribute.
Therefore, in the dispute between philosophers and mystics in this regard, the opinion of mystics is preferable; In the present article, we have dealt with these issues .