From a cognitive science perspective, '1 + 1 = 2' represents a fundamental human capacity for 'numerosity' – the ability to perceive and manipulate quantities. Research shows that even animals possess a basic number sense, but humans develop sophisticated symbolic systems to represent these quantities. The acquisition of '1 + 1 = 2' in children typically moves from concrete experiences (e.g., combining two toys) to abstract understanding. This journey highlights the interplay between innate cognitive modules for number and the cultural transmission of symbolic mathematical language, demonstrating how our brains map physical reality onto abstract mathematical concepts.