Philosophy of Science: Baconian and Cartesian Approaches

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Philosophy of Science: Baconian and Cartesian Approaches

Overview

The Renaissance and Scientific Revolution encompassed the transformation of art, science, medicine, and philosophy, as well as the social, economic, and political life of Europe. Ancient concepts were challenged by new ideas and facts generated by the exploration of the world, the heavens, and the human body. Natural philosophers, physicians, and surgeons were confronted with plants, animals, and diseases unknown to the ancient authorities. Although Francis Bacon (1561-1639) and René Descartes (1596-1650) developed different methodologies, these two seventeenth century philosophers helped to guide and systematize the new sciences and define the modern scientific method.

Background

Although he made no direct contributions to scientific knowledge, Francis Bacon is remembered as Britain's major seventeenth-century British philosopher of science. A keen observer of the great events of his time, Bacon said that of all the products of human ingenuity the three most significant were the compass, gunpowder, and printing. Through their combined effects, Bacon argued, these inventions had "changed the appearance and state of the whole world." Bacon himself became the guiding spirit of the new experimental science and the scientific societies that nurtured it. His impact on the sciences came about through his emphasis on defining the methodology of science, suggesting means of insuring its application, and providing encouragement and direction for the new scientific enterprises he predicted. Bacon planned an encyclopedia of the crafts and experimental facts, a review of all branches of human knowledge, and new scientific institutions that would improve human welfare, comfort, and prosperity. Ultimately, according to Bacon, science would increase human knowledge, power, and control over nature. Bacon rejected the scholasticism of the universities and launched open attacks on Aristotle and Plato. He insisted that fact gathering and experiment must replace the sterile burden of deductive logic so that naturalists could produce new scientific knowledge.

Bacon's Advancement of Learning (1605) proposed a new science of observation and experiment to replace traditional Aristotelian science. The Baconian method, also known as the inductive method, involves the exhaustive collection of particular instances or facts and the elimination of factors, which do not accompany the phenomenon under investigation. Generally suspicious of mathematics, deductive logic, and intuitive thinking, Bacon believed that valid hypotheses should be derived from the assembly and analysis of "Tables and Arrangements of Instances." Rather than passively collecting facts, the scientist must be actively involved in putting questions to nature. Scientists would analyze experience "as if by a machine" to arrive at true conclusions by proceeding from less to more general propositions. The result of applying this scientific method, Bacon assured his readers, would be a great new synthesis of all human knowledge, a true and lawful marriage between the empirical and the rational faculty. Nevertheless, Bacon apparently appreciated the significance of what is now known as the falsifiability principle, which is usually associated with the twentieth-century philosopher Karl Popper (1902-1994). Despite his enthusiasm for the collection of facts, Bacon realized that it is impossible to provide absolute proof of inductive generalizations based on a finite number of observations. Because a few "negative instances" have the power to falsify an induction, experimental results that contradict a general theory may reveal more about nature than another bit of data that appears to support the theory.

Like Bacon, the French philosopher René Descartes believed that a new science would lead to knowledge and inventions that would promote human welfare. Unlike Bacon, Descartes was a gifted mathematician, honored as the inventor of analytic geometry, and the advocate of a deductive, mathematical approach to the sciences. Descartes believed that his approach to science would allow human beings to master and possess nature's abundance and establish a new medical science capable of eliminating disease and extending the human life span. Unlike Bacon, whose work he had studied and criticized, Descartes placed a priori principles first and subordinated his observations and experimental findings to them. Nevertheless, he too had a grand scheme and task for natural philosophy. An examination of method was a primary part of his plan to use the mathematical method in developing a general mechanical model of the workings of nature. Although experimentation had a role in Descartes's system, it was a subordinate one. He believed that experiments should serve as illustrations of ideas that had been deduced from primary principles or should help decide between alternative possibilities when the consequences of intuitive deduction were ambiguous.

Following Bacon's example, Descartes also opposed scholastic Aristotelianism and called for new approaches to science and philosophical inquiry. Applying his methods to science, philosophy, or any other rational inquiry, Descartes asserted, would not only resolve problems but would lead to the discovery of useful philosophical knowledge. Descartes began by methodically doubting knowledge based on authority, the senses, and reason. Ultimately, he found certainty in the intuitive knowledge that he was thinking, and, therefore, he must exist. He expressed this insight in his famous declaration: "I think, therefore I am." Descartes developed a dualistic system that separated mind, the essence of which is thinking, from matter, the essence of which is extension in three dimensions.

Descartes's metaphysical system is intuitionist, derived by reason from innate ideas, but his physics and physiology, based on sensory knowledge, are mechanistic and empiricist. The mechanistic philosophy asserts that all life phenomena can be completely explained in terms of the physical-chemical laws that govern the inanimate world. Vitalist philosophy claims that the real entity of life is the soul or vital force and that the body exists for and through the soul, which is incomprehensible in strictly scientific terms. The writings of Descartes provided the most influential philosophical framework for a mechanistic approach to physiology. Descartes's own physiological experiments and texts provided his followers with a complete and satisfying mechanistic system, embedded in a general system of philosophy. The fundamental platform of Descartes's mechanical philosophy was that all natural phenomena could be explained solely by matter and motion. In his Treatise of Man, Descartes extended his concept of the universe as a machine to the explanation of human beings as machines working in accordance with physical laws.

Impact

Cartesian doctrine essentially treated animals as machines whose activities were explained in purely mechanical terms as the motions of material corpuscles and the heat generated by the heart. Descartes systematized the mechanical philosophy and provided a rationale for describing the human body as a machine. Even human beings could be investigated as earthly machines that differed from animals only because they possessed a rational soul that governed their actions. Serving as the agent of thought, will, conscious perception, memory, imagination, and reason, the rational soul was the only entity exempted from a purely mechanical explanation. Except for thought processes, all physiological functions of the human body were as mechanical as the workings of a clock.

Descartes challenged scientists to treat the physical and mental aspects of human beings in the same manner as all other scientific problems. According to Descartes, a human being is a union of mind and body, two dissimilar substances that interact only in the pineal gland. He reasoned that the pineal gland must be the uniting point because it is the only nondouble organ in the brain, and double reports, as from two eyes, must have one place to merge. He argued that each action on a person's sense organs causes subtle matter to move through tubular nerves to the pineal gland, causing it to vibrate distinctively. These vibrations give rise to emotions and passions and cause the body to act. Bodily action is thus the outcome of a reflex arc that begins with external stimuli and involves first an internal response, as, for example, when a soldier sees the enemy, feels fear, and flees. The mind cannot change bodily reactions directly—for example, it cannot will the body to fight—but it can change the pineal vibrations from those that cause fear and fleeing to those that cause courage and fighting.

Even though the nervous system carried out the commands of the rational soul, Descartes provided a mechanical explanation for the nervous system. Direct interaction between the rational soul and the earthly machine occurred in the pineal gland, an unpaired organ that was erroneously thought to be present only in humans. Through conduits in the brain, the animal spirits were able to enter the nerves, which were hollow tubes that incorporated hypothetical valves governing the flow of nervous fluid. Delicate threads along the length of the interior of the nerves connected the brain to the sense organs. The tiniest motion along the thread tugged at the site of the brain where the thread originated and opened pores that allowed the animal spirits to flow into the muscles. Bodily action was, therefore, the result of a reflex arc that began with external stimuli and involved an internal response. Movement of the subtle fluid through the nerves in response to stimulation of the sense organs caused the pineal gland to vibrate, resulting in changes in the emotions and passions. Although the mind could not change bodily reactions to external stimuli directly, it could affect the distinctive pineal vibrations. Thus, external stimuli could cause fear, but the mind could determine whether the reaction would be flight or fight.

Descartes's work was widely read, imitated, and honored. He challenged scientists to treat the physical and mental aspects of human beings in the same manner as all other scientific problems. His disciples saw him as the first philosopher to dare to explain all the functions of human beings, even the brain, in a purely mechanical manner. Guided by Descartes, many seventeenth century physiologists tried to force all vital phenomena to fit mechanical analogies. Such physiologists were known as iatromechanists, because they believed that all functions of the living body could be explained on physical and mathematical principles. In contrast, iatrochemists attempted to explain vital phenomena as chemical events. The mechanical philosophy allowed naturalists to investigate nature without relying on the vitalistic "soul" and "spirits" that had characterized ancient and Renaissance science. Only the rational soul of human beings remained.

Descartes's influence on philosophy, literature, and French culture was both profound and subtle. Eventually, however, it was the "Baconian method" that became virtually synonymous with the "scientific method." Nevertheless, neither Descartes nor Bacon alone could have served as a complete guide for the development of experimental and theoretical science. Even some of their contemporaries recognized the deficiencies of the pure Baconian system and the pure Cartesian system. The great mathematician and physicist Christiaan Huygens (1629-1687) recognized this when he remarked that Descartes had ignored the role of experimentation, while Bacon had failed to appreciate the role of mathematics in scientific method. A synthesis of the two approaches was needed, or the admission that there is no one scientific method sufficient for posing and solving all possible problems. Mechanical fact-finding, daydreams, and flashes of intuition have played a role in science, no matter what formal doctrine or method scientists professed to follow.

LOIS N. MAGNER