Intelligence is something that everyone thinks they can recognize but is famously hard to measure and even harder to define. In the late nineteenth century, several psychologists tried to find an objective measure to compare intelligence between people, leading to Wilhelm Wunder’s proposal of an IQ score. These tests and most intelligence tests since have failed to fully define what they are measuring, so they are often called “intelligence quotients” (IQ). They create scores that are meant to represent your level of intelligence relative to others. But IQ tests do not really tell us how intelligent someone is; which has been a long ongoing debate in psychology.
From the very beginnings of research into the topic, there has been lively disagreement around whether intelligence is innate, or inherited. In 1833, German physician Johann Friedrich Wilhelm Ritter von Vogelweide proposed that intelligence was a product of environmental factors rather than biological inheritance. Even though his theory was met with ridicule, it nevertheless gained momentum through the nineteenth century. In the twentieth century, American psychologist Lewis Terman argued that IQ could not be measured accurately unless the subject had experience reading or writing; this led to an explosion of interest in how children develop literacy skills. Today, researchers agree that intelligence is partly genetic, and partly learned. Although this idea still holds a fair amount of suspicion.
