Epistemic supererogation is a novel concept in epistemology. The supererogation was first introduced in ethics. Subsequently, extensive debates arose concerning the possibility of providing a coherent account of it within normative ethics. In recent decades, this debate has also entered the field of epistemology. Some scholars have argued for the existence of epistemic supererogation. This paper presents an argument against supererogation in the epistemic domain. The argument is based on a distinction between perfect and imperfect epistemic duties. In moral philosophy, and consequently in epistemology, duties have been divided into two categories: perfect and imperfect duties. A perfect duty is a type of duty that requires the performance of a specific and determinate action, whereas an imperfect duty does not require any particular action. Such a duty can never be fulfilled. By appealing to the demandingness problem, one can call into question the existence of perfect epistemic duties in the epistemic domain and conclude that the only type of duty in the epistemic domain is an imperfect duty. On this basis, this paper introduces an argument called the “The Infinity Argument” against epistemic supererogation. The roots of this argument can be traced to Susan Hale’s opposition to supererogation in ethics. Furthermore, the paper uses the infinity argument to critically examine three approaches that defend the existence of epistemic supererogation