The Lines of Development from Philosophy

Although the five trends from science left their impress on later psychology, the contributions of philosophy to the emerging independent discipline of psychology were no less marked. Indeed, in the first third of the 20th century, psychology was still typically taught in departments of philosophy. Although the trends from science largely concern a collection of facts and discoveries, with empirical investigation, mathematical thinking, and a set of popular research areas dominating the Zeitgeist, those from philosophy are more a series of significant fundamental problems, with various different answers and occasional reformulations of the problems proposed by successive philosophers. Each of the three trends— critical empiricism, associationism, and scientific materialism—had a profound influence on psychology, so each one will be considered briefly here in turn.

Critical Empiricism

Before critical empiricism could flourish, there had to be a change in attitude from the one that prevailed in the Middle Ages, when writers derived their knowledge from authorities such as Aristotle and the Church Fathers. The acceptance of the idea that one should find out for oneself, the break with authority in science, occurred primarily in the 16th century—during the Reformation, when the priests’ dicta began to be questioned. If one wanted to know how many teeth a horse has, maybe one should look not in a book but in a horse’s mouth, even at the risk of getting one’s finger of cherished authoritarian prejudice bitten in the process.The Zeitgeist changed with the discovery of America and the rediscovery of old Latin and Greek texts, and there were major political events, such as the fall of Constantinople marking the end of the Byzantine Empire, which demonstrated that the order of things to which people were accustomed was not necessarily permanent or the best.

Early Empiricists

Among the influential thinkers who carried the new spirit of freedom of inquiry into scientific matters were Nicolaus Copernicus, who dared to differ with authority in opposing Ptolemy’s geocentric system by proposing that the sun, not the earth, is the center of the universe, and Johann Kepler, who mathematized

Copernicus’s formulations using his own and Tycho Brahes measurements of the movements of the heavenly bodies. In the conceptions of these astronomers, human beings and the earth are not at the center of everything, the earth is not flat but spherical, and the motions of the heavenly bodies are not perfectly circular but elliptical.

Empirical measurement overrode authority and disturbed deeply entrenched beliefs, traditions, and social mores. In 1600 William Gilbert employed a strictly experimental method in the study of magnetism, holding certain variables constant while varying others systematically. About the same time Galileo Galilei was developing an empirical and quantitative approach to mechanics and physics, examining natural phenomena rather than Aristotle or Aquinas to achieve an understanding of the physical environment. Sir Francis Bacon extolled the virtues of an inductive, observational approach to knowledge in his Novum Organum (1620) and proposed that the sciences are related in a hierarchy and should be used as a guide to reform society'. The British physiologist William Harvey published his work on the circulation of blood, heralding the new era of an empirical approach to biology. The application of measurement to physical phenomena was extended to the study' of light and gravitation by Isaac Newton. The break with authority' pervaded the Zeitgeist.

Many' questions central to the concern of the critical empiricists had, however, already' been asked by the Greeks. They were curious about what the world is made of and how it is possible for a mere human to obtain knowledge of it. Critical empiricism tries to answer both of these questions, but primarily the second one. It was in response to the first question that the sciences of physics, chemistry, and biology arose, and methods for reliable observation were developed. But in response to the second, the critical empiricists asked: What do we contribute to the knowledge we experience? What is the nature of our experience? How does the world of experience relate to the world of physical objects?

One of the most important forms of this question was the nativism—empirism issue: namely, are we born with certain ideas, or do all the contents of our mind enter it through experience? From Plato down through René Descartes, it was believed that we are born with at least some ideas, such as the axioms of geometry; many' later philosophers tended more to the empirism of Aristotle, holding that we are born without knowledge of specific ideas and that all of our thoughts develop in some way' or another from our experience of the world about us.

The philosophical underpinnings of knowledge were a central concern of all empiricists. Consider briefly' the thought of two early modern philosophers, Descartes and Hobbes; the contrasting views of Spinoza, Locke, and Leibniz; the influential doctrines of British empiricists Berkeley' and Hume; followed by' the German philosopher Kant’s disagreement with much of the empiricist tradition.