This chapter looks at claims to understanding. It begins by looking at the system I have worked on, the lamprey spinal cord locomotor circuit, and claims that circuit function and behaviour can be understood in terms of the interactions of spinal cord nerve cells. I highlight that the claims to experimental confirmation actually reflect various assumptions and extrapolations and that the claimed understanding is lacking. I then look at the Nobel Prize winning work on the Aplysia gill withdrawal reflex, making the same conclusion as the lamprey, various assumptions and extrapolations are used to claim causal links, and in doing this commit various logical fallacies, including confusing correlation for causation and begging the question. I finish by looking at hippocampal long-term potentiation and claims it is the cellular basis of memory, again highlighting that the claimed links have not been made.