This paper aims to review the definition by hadd and consequent difficulties. The author maintains that defining by h as it’s discussed in philosophy and logic, does not solve any problem. Among Muslim philosophers, Sohrevardi believes that defining by h i.e. defining by genus and defferentia (jins wa fasl) is impossible. Thus he considers the Perpatetic (massha) method to be wrong. He proposes that in order to have knowledge of something one should use a set of particular concomitants of that.
)