Jean Piaget proposed four stages of cognitive development known as genetic epistemology: 1) The sensorimotor stage from birth to age 2 where infants learn about the world through senses and physical interaction. 2) The preoperational stage from ages 2 to 7 where symbolic thought and language develops but logical thought is still limited. 3) The concrete operational stage from ages 7 to 11 where logical thought emerges and children can think about concrete events. 4) The formal operational stage from age 11 onward where abstract and logical thought allows for hypothetical deductive reasoning.