P- however, one weakness of the the cognitive approach is that it does not explain the origin of irrational thoughts.
E- since most of the research in this area is correlational, psychologists are unable to determine if negative, irrational thoughts cause depression, or whether a person's depression leads to a negative mindset
L- consequently, it is possible that other factors, for example genes and neurotransmitters, are the cause of depression and the negative, irrational thoughts are a symptom of depression