Formal Operational Stage as suggested by Piaget : At about the age of twelve Piaget suggested, most children enter the final stage of cognitive development – the stage of formal operations, During this period, major features of adult thought make their appearance. While children in the earlier stage of concrete operations can think logically, they can do so only about concrete events and objects. In contrast, those who have reached the stage of formal operations can think abstractly; they can deal not only with the real or concrete but with possibilities – events or relationships that do not exist, but can be imagined.
Hypothetical thinking : With formal operations, boys and girls moved from the actual world to the hypothetical world. They can still think about the way things are, but they become much more skilled at thinking about how things might be if certain changes took place. Such thinking allows adolescents to judge the ‘reasonableness’ of a purely hypothetical line of reasoning.
Deduction and induction : Hypothetical and abstract thinking make sophisticated deduction and induction possible. Deduction is reasoning from abstract, general principles to specific hypothesis that follow from these principles. Induction thinking is the complementary process of observing a number of specific events or instances and inferring an abstract general principle to explain those instances. The two processes can be seen in the adolescents reasoning about nature, science and even social problems.
Inter-propositional logic : The formal operations involve the ability to judge whether propositions are logically connected to one another, regardless of whether the propositions are true. This is called inter propositional logic.
Reflective thinking : This allows the formal operational person to be his or her own critic, to evaluate a process, idea of solution from the perspective of an outsider and to find errors or weak spots in it. The reflective thinker can then sharpen plans, arguments or points of view-making them more effective, more powerful.