Individuals, Populations, and Races
Experience shows that every person we meet is different from any met before. Individual differences exist also among animals and plants, and for that matter no two material objects are completely identical. Yet human language forces the infinite variety of experience into categories symbolized by words--man, horse, dog, pine, etc. It is easy to mistake words for actual objects, and to conclude that each word refers to some metaphysical entity or "idea." Plato, the greatest philosopher of antiquity, actually taught that individual men, horses, pine trees, etc., are imperfect and temporary expressions of the eternal and unchangeable ideal Man, Horse, and Pine.
Although few modern philosophers and still fewer scientists take Plato's "ideas" literally, his way of thinking is deeply rooted in many minds. It is common to hear people speak glibly of a "typical Frenchman," or "real American," or "ideal horse." Such expressions are legitimate only so long as the speaker realizes that the "type" or "ideal" is a composite image which he endows with properties commonly met with in actual individuals or considered desirable or pleasing. The trouble is that people are frequently tempted to think of these abstractions as though they were real entities. This "typological" thinking may even be carried to the point when the imaginary Man or the imaginary American is substituted for real men and for living persons who compose a nation as objects of sympathy and affection.
Types and Classifications . The typological approach is convenient in the branches of biology which deal with description and classification of animals and plants. Just as a large library must be systematized and catalogued to be usable, so living organisms have been divided into phyla, classes, orders, families, genera, species, and sub