Abstract

Stem cells are defined as having capacities for both self-renewal and differentiation. Many different entities satisfy this working definition. I show that this general stem cell concept is relative to a cell lineage, temporal duration, and characters of interest. Experiments specify values for these variables. So claims about stem cells must be understood in terms of experimental methods used to identify them. Furthermore, the stem cell concept imposes evidential constraints on interpretation of experimental results. From these constraints, it follows that claims about stem cell capacities are inherently uncertain. This result has important implications for stem cell research