 This inferential problem has led some commentators to maintain highly skeptical views concerning our ability to use animals as models for humans in biomedical research. Hugh LaFollette and Niall Shanks argue that animal models cannot be reliably used for extrapolation at all, but at best only heuristically, as sources of hypotheses that have to be tested on humans (LaFollette and Shanks 1997). They introduce two terms to make their argument: causal analogue model (CAM) and hypothetical analogue model (HAM). The former can be used to make reliable predictions about target populations of interest; the latter only heuristically. The main premise in their argument that animal models in biomedical research are at best HAMs but not CAMs is that for a model to be a CAM there cannot be causally relevant disanalogies between model and target—a condition which is rarely if ever met by animal models (again, this is why we study animals in the laboratory in the first place).