One important question that the emergence of philosophical or rational Kalam has raised is what rationalism in the so-called Kalami (theological) schools actually means. This paper investigates the answers to the aforementioned question in Shi’a Kalam. Also, we have a comparative look at the philosophical Kalam and the rational one, concluding the identity of Shi’a Kalam with Shi’a philosophy. In this work, we have referred to three types of rationalism: personal, Vahmi (imaginal), and Hikmi (philosophical) rationalism. In short, our answer to the above question would be that, Shi’a Kalam – specially in Khaje Nasir’s works – is based on Hikmah (philosophy), and so, rationalism in this school does not refer but to this approach. This type of rationalism is in contrast to the personal or Vahmi rationalism. As a matter of fact, Those Mutakalims (theologians), who use Hikmi rationalism, don’t try to criticize philosophy or elicit from it; they just try to employ the principles, foundations, and results of Hikmah to explain, justify, and defend their religious beliefs.