vity. The next stage in Piaget's cognitive development theory is the pre-operational stage. This takes place from about two to seven years of age. During this stage, the child's language develops. They develop a representational system and use symbols such as words to represent people, places, and events. From about seven to thirteen years of age, Piaget believes children enter the concrete operational stage. They can solve problems logically. They can understand rules and form concepts. Some children become moralistic. The last stage Piaget believes is the formal operational stage. This stage takes place from about twelve years of age through adulthood. Once someone has reached this stage, one should be able to think abstractly, manipulate abstract concepts, use hypothetical reasoning, and use creative language. These three theories on human development each have their own good and bad points. One problem all theories must deal with is paradigmatic assumptions. These are ideas that the theorist has taken for granted as facts. An example is Freud's notion that women suffer from a lack of self-esteem or self worth all their lives because of penis envy. Freud's assumption could have derived merely because of the time when he lived, and it was a time when women were treated as second class citizens. Freud's assumption that sex is the driving force behind everything could also be a product of his times. Sexual feelings were often repressed. The problem with paradigmatic assumptions is that each person grows up in a different culture and some theories don't apply to everyone. The problem with psychology remains that it is not an exact science. It is difficult to develop good paradigmatic assumptions because of that. Erikson assumes a child must learn these virtues or skills in this order. But, what if a child does not? Someone may never have a meaningful relationship, but they may develop wisdom. This would undercut Erikson's assumptions tha...
