Thick, thin, and ultra-thin posits are distinguished. The four epistemic burdens on thick epistemic access, robustness, refinement, monitoring, and grounding, are described. The epistemic burden on thin posits, Quinean rent plus a defeasibility condition, are also described.
Keywords: epistemic burdens, grounding, monitoring, Quinean rent, refinement, robustness, thick posit, thin posit, ultra-thin posit