Your friend says, "Of course elephants are smarter than dolphins: they have much bigger brains." Why is your friend's reasoning incorrect? What factors is he not taking into account to explain differences in brain size?

Your friend's reasoning is incorrect because brain size alone does not determine intelligence. While it is true that elephants have larger brains than dolphins, the size of the brain does not necessarily correlate with cognitive abilities.

Your friend is not taking into account the concept of encephalization quotient, which is a measure of brain size relative to body size. Dolphins actually have a higher encephalization quotient than elephants, indicating that their brains are more developed in relation to their body size.

Additionally, the structure and organization of the brain, as well as the number of neurons and connections within the brain, are also important factors in determining intelligence. Dolphins have complex social structures, communication abilities, problem-solving skills, and self-awareness, all of which are indicative of high intelligence.

Therefore, it is not accurate to claim that elephants are smarter than dolphins simply based on brain size. Intelligence is a complex trait that is influenced by various factors, and cannot be determined solely by the size of the brain.