God made man in his own image, and one of the noblest features of the divine likeness in man is his capacity to think. (14)
Only man has what the Bible calls “understanding” (cf. Psalm 32.9). (14-15) Scripture assumes this from the beginning of man’s creation. In Genesis 2 and 3, God expects man to discriminate – rationally as well as morally – between what he is permitted to do and the one thing he is prohibited from doing.
This basic rationality of man by creation is everywhere taken for granted. Indeed, Scripture bases upon it the regular argument that since man is different from the animals, he should behave differently (Psalm 32.9). Consequently, man is mocked and rebuked both when his behavior is more bestial than human (Psalm 73.22) and when the behavior of animals is more human than that of some human beings (Prov. 6:6-11; Isaiah 1:3; Jeremiah 8:7). (15)
But animals were created to behave by instinct, human beings, by intelligent choice. So when humans fail to do by their own mind and consent what animals do byy instinct, they are contradicting themselves, contradicting their creation and their distinctive humanity, and they ought to be ashamed of themselves.
-John Stott, Your Mind Matters, 14-16.