"If all people are equal, then you and I must be equal." This sentence represents type of reasoning that, according to Piaget, generally emerges between the ages of 12 and 16.

Deductive logic

Explanation:

The Cognitive development theory of Jean Piaget suggests that there are four stages through which a child develops mentally.

The fourth or the last stage of the theory is the Formal Operational Stage. This occurs at the age of 12 and above. In this stage, a child develops through certain skills such as systematic planning, deductive reasoning, etc.  

According to Piaget, deductive logic or reasoning is a type of reasoning that involves using of general statement or hypothesis to reach a particular outcome.

The sentence given in the question is an example of deductive reasoning.

The general statement is "if all people are equal" and the outcome abstracted from this general statement is "then you and I must be equal."

So, the correct answer is deductive reasoning.

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