Respect for human embryos is often defended on the basis of the potentiality argument: embryos deserve respect because they already possess potentially the features that in adults are fully actualized. Opponents of this argument challenge it by claiming that if embryos should be respected because they are potentially adults, then gametes should be respected because they are potentially embryos. This article rejects this reductio ad absurdum argument by showing that there are two different types of potentiality involved so that the (...) transitivity of potentiality does not hold up in this case. Respect for embryos does not logically entail respect for gametes. (shrink)