Oligophrenia is a form of intellectual disability marked by persistent underdevelopment of cognitive function, caused by organic damage to the central nervous system during the prenatal, perinatal, or early postnatal period.
Modern medical classification recognizes three degrees of oligophrenia, based on the depth of intellectual impairment:
- Moronity (mild) — IQ 50-69
- Imbecility (moderate to severe) — IQ 20-49
- Idiocy (profound) — IQ below 20
The main clinical symptoms include:
- Reduced capacity for abstract thought
- Impaired analytical and synthetic brain function
- A limited vocabulary
- Concrete thinking and difficulty with generalization
- Reduced ability to learn
- Impaired memory and attention
- Inertia of mental processes
- Disturbances of emotion and will
In the phrase "a moron’s certainty came over me," the author metaphorically describes a particular type of confidence characteristic of people with oligophrenia: unshakable and categorical, absent any adequate basis or critical reflection. People with oligophrenia often show a directness of judgment, a black-and-white view of the world, and an oversimplified reading of complex phenomena, paired with an absolute, unquestioning conviction of being right.
By using this expression, the hero likely means he was suddenly seized by a feeling of total, unappealable certainty about something, a certainty that wasn’t the product of critical analysis or logical reasoning, but arose intuitively, beyond question, echoing the simplified, direct, and uncritical perception of reality typical of people with intellectual disability.