How many times when I ask patients about their depressive or manic symptoms, they always tell me: “Yes, but I am depressed because of the …… factor” or “I am only depressed when I am really interested in something mania”. There have been many times when I have seen psychiatrists downplay the diagnosis of a mood disorder, believing that the illness is related to psychological stress. Some critics against psychiatry, especially sociologists and psychologists, stand in a seemingly erudite position and say that psychiatry simply makes diagnoses for patients, such as depression, while ignoring the causes in life that lead to these disorders. How many times have we heard the criticism that psychiatry has labeled all everyday behavior as medical. This criticism is true but only half true. We do make some overdiagnoses that predate contemporary biological psychiatric reductionism: for a century, psychoanalysts have overly attributed pathological states even when only biological simplifications are required. The problem with these criticisms and perceptions is that they reflect a very deep misunderstanding of psychology and psychiatry, much deeper even than the misunderstandings about biology and genetics that I have explored. There is nothing worse for psychology and psychiatry than these misconceptions. The issue is obvious and will be raised someday. Most of these psychological judgments are based on common sense. But if common sense can explain everything, then our patients should be able to diagnose themselves, or be diagnosed by family and friends. Once the patient crosses over to the doctor’s office, then that common sense is no longer valid and there is no need to continue using it. A large body of literature on life events and depression shows that the vast majority of depressive episodes precede a life event that “causes” depression. What are the so-called life events? Relationship problems with spouse, boss, children? Or financial problems? Or is it another illness? If it is these life events that cause depression, who has not experienced these troubles? The question we face is not why do these events cause depression, but why don’t they make 90% of people depressed? Most people are the ones who have never experienced a major depressive episode. Obviously, there are other factors that influence the onset of depression. Contrary to what psychologists “hope”, biological factors influence the onset of depression. The ultimate proof of this psychological fallacy is the brain crack test. In the 1970s and 1980s, some patients with severe epilepsy were treated with corpus callosotomy, a procedure that prevents seizures from passing from one hemisphere to the other, thus avoiding generalized convulsions. This procedure has facilitated some interesting neuropsychological studies. By showing a picture, such as a lady on the phone, to the left visual field of a right-handed patient, researchers can detect how the patient describes the image he sees. This is because information cannot be transmitted from one hemisphere of the brain to the other (most people with right-handedness have their language center in the left side of the brain). In this test, the patient would describe a different view than the picture. But if the patient was asked to demonstrate the scene she saw, she would pick up the phone with her left hand. This indicates that she received the information, but could not express it. More importantly, the patient did not simply admit that she could not speak, but made up the scene she “saw”! This fictional process is the work of the human brain. AsGazzaniga, the lead researcher on this topic, said that the brain is a machine that rationalizes what it sees and comes up with an answer for everything. Sometimes we are right, sometimes not, and we don’t know if we are right when faced with a situation. But we can always give coherent and logical explanations based on our past experiences, but this is not true: “Of course we can explain, we can always explain”. But sometimes explanations based on “common sense” are wrong, especially when there are other factors, such as biological factors, or illness. Psychosocial life events can influence the duration of depressive episodes, but in patients with recurrent depression, biological factors are the underlying cause of the ease of recurrent episodes. This is why the same life event can cause depression in 10% of people, but not in the other 90%. This is why we have to be careful with the concept of psychiatry and take into account biological factors, rather than simply generalizing.