What is a hallmark of Piaget's formal operations stage?

Piaget's formal operations stage, which typically emerges around the age of 12, is characterized by the development of logical thinking and the ability to use deductive reasoning. In this stage, individuals can think abstractly and hypothetically, allowing them to solve problems using systematic planning and manipulate ideas in their mind without the need for concrete, physical objects. This marks a significant maturation in cognitive capability compared to earlier stages, where thinking was more concrete and tied to direct experiences.

Logical thinking entails the ability to form and manipulate concepts and propositions; for example, individuals can consider theoretical situations that are not concrete in reality. This is crucial for higher-level math and sciences, as well as for philosophical reasoning. Those in the formal operations stage can also evaluate conditions, form hypotheses, and test them systematically. Thus, the hallmark of this developmental stage is indeed logical thinking.