Our first mental endowment was instinct. Then came thought, and later language. Thanks to language, thought then proceeded to flourish. Such was our phylogeny. Ontogeny, then, true to form, recapitulates the sequence in the development of each child. By instinct a child a few days old will show anxiety when an object moving steadily to a screen and behind it fails to emerge on schedule at the far edge. Also new-borns are said to respond emotionally to emotional facial expressions and even to imitate them.
W. V. Quine is Emeritus Professor of Philosophy at Harvard University