Which of the following theorists proposed that children’s thinking is…

Concept: Piaget's theory of cognitive development holds that children's thinking is not simply a smaller-scale or less-informed version of adult thinking; children pass through a fixed sequence of stages (sensorimotor, preoperational, concrete operational, formal operational), and reasoning at each stage is governed by a distinct underlying logical structure rather than by degree alone.

Application: The question asks which theorist proposed exactly this claim — that children's thinking is qualitatively different from that of adults. This is the defining feature of Piaget's stage model: for example, a preoperational-stage child judges quantity by appearance and lacks reversible operations, reasoning in a way an adult in the formal-operational stage does not use at all, not merely 'less well.' This structural shift across stages is what makes the difference qualitative rather than quantitative.

Cross-check: Comparing each theorist's own emphasis against the stem confirms the match and rules out the other options:

• Lev Vygotsky's sociocultural theory explains development through social interaction, language, and cultural tools within a Zone of Proximal Development, not through a universal sequence of qualitatively distinct stages.

• Howard Gardner's theory of multiple intelligences classifies several relatively independent types of ability (linguistic, logical-mathematical, spatial, and others), not a progression in how thinking itself changes with age.

• Lawrence Kohlberg's stage theory concerns the development of moral reasoning (pre-conventional, conventional, post-conventional), not general cognitive thinking.