The problem of consciousness has been an issue in philosophy of mind for decades, and in recent years panpsychism and panprotopsychism have gained attention among philosophers who are still dedicated to finding a complete explanation of consciousness. In this dissertation, I criticize panpsychism and panprotopsychism by examining their metaphysical plausibility and their epistemic prospects. Concerning the metaphysical plausibility of panpsychism and panprotopsychism, I explain the “combination problem” of panpsychism and criticize several major accounts of panpsychism and panprotopsychism that aim at solving this problem, including Seager’s panpsychist infusionism, Goff’s phenomenal bonding proposal, and Coleman’s panqualityism. I also examine the proposal of motivating panpsychism and panprotopsychism by drawing support from the integrated information theory (IIT) of consciousness. I argue that this proposal to merge panpsychism or panprotopsychism with IIT does not work. Concerning the epistemic prospect of panpsychism and panprotopsychism, I raise concerns about whether panpsychism and panprotopsychism can guide a fruitful research program about the nature of consciousness. First, I argue that a theory based on Russellian Monism would not have a promising epistemic prospect. I compare Russellian Monism to Thomistic Hylomorphism and argue that Russellian Monism faces similar epistemic challenges that plagued Thomistic Hylomorphism. Since most theories of contemporary panpsychism and panprotopsychism rely on the metaphysical framework of Russellian Monism, the challenges to Russellian Monism also undermine the epistemic prospects of panpsychism and panprotopsychism. Second, I challenge the epistemic prospects of panpsychism and panprotopsychism by examining if there can be a viable method to study the consciousness of micro-level entities. After revisiting the reasoning process that guided the study of atoms, I argue that studying micro-level facts requires “analogies” that compare micro-level facts with macro-level models. Then I argue that an analogy that fits the need of panpsychism or panprotopsychism is hard to achieve, because we have no macro-level models to be compared to the hypothesized systems of micro-level consciousness.