> I don't know what ^ means here Logical conjugation ("and"). I should have used ¬ instead of ! to have been more conventional. > Is it [flawed to deduce (abn

> I don't know what ^ means here Logical conjugation ("and"). I should have used ¬ instead of ! to have been more conventional. > Is it [flawed to deduce (abnormal brain -> psychopath) from (psychopath -> abnormal brain)]? Yes. That they show the group has a brain anomaly, and hypothesise a mechanism which links it to the behaviour is not enough. It's plausible that people who possess this brain abnormality within the rest of the population commonly are not psychopaths. You aren't going to find that within "22 healthy non-offenders", the sample is too small. > So they found a link, causal or not, between abnormalities and psychopathy I don't dispute this. > There seem to have been other studies too, from wikipedia "Blair, R. J. R. (2003). "Neurobiological basis of psychopathy". They aren't making the conclusion that the brain anomaly implies psychopathy, they only theorise a biological basis for it being foundational. Furthermore their article they states: "However, all of these studies, with the exception of one by (Raine et al, 2000), have been with violent offenders rather than individuals with psychopathy. [...] Indeed, neuropsychological work with individuals with psychopathy, unlike work with individuals who are violent, has repeatedly found frontal functioning to be intact (Kandel & Freed, 1989)." This gives more weight to the argument that it is flawed to make deductions primarily by studying incarcerated offenders. Neuropsychological studies are often compromising. Scanning brains is expensive. I don't believe that these researchers are stupid, as you asked, but it would be silly to say that scientists never theorise without concrete proof. Neurobiology is still highly hypothetical, and experiments are often very limited by practical and ethical concerns. > why did you mention serial killers? From the Smithsonian article: "neuroscientist James Fallon was looking at brain scans of serial killers."