Empiricism

Empiricism is the theory that the origin of all knowledge is sense experience. It emphasizes the role of experience and evidence, especially sensory perception, in the formation of ideas, and argues that the only knowledge humans can have is a posteriori (i.e. based on experience). Most empiricists also discount the notion of innate ideas or innatism (the idea that the mind is born with ideas or knowledge and is not a "blank slate" at birth).

In order to build a more complex body of knowledge from these direct observations, induction or inductive reasoning (making generalizations based on individual instances) must be used. This kind of knowledge is therefore also known as indirect empirical knowledge.

Empiricism is contrasted with Rationalism, the theory that the mind may apprehend some truths directly, without requiring the medium of the senses.

The term "empiricism" has a dual etymology, stemming both from the Greek word for "experience" and from the more specific classical Greek and Roman usage of "empiric", referring to a physician whose skill derives from practical experience as opposed to instruction in theory (this was its first usage).

The term "empirical" (rather than "empiricism") also refers to the method of observation and experiment used in the natural and social sciences. It is a fundamental requirement of the scientific method that all hypotheses and theories must be tested against observations of the natural world, rather than resting solely on a priori reasoning, intuition or revelation. Hence, science is considered to be methodologically empirical in nature.

The concept of a "tabula rasa" (or "clean slate") had been developed as early as the 11th Century by the Persian philosopher Avicenna, who further argued that knowledge is attained through empirical familiarity with objects in this world, from which one abstracts universal concepts, which can then be further developed through a syllogistic method of reasoning. The 12th Century Arabic philosopher Abubacer (or Ibn Tufail: 1105 - 1185) demonstrated the theory of tabula rasa as a thought experiment in which the mind of a feral child develops from a clean slate to that of an adult, in complete isolation from society on a desert island, through experience alone.

Sir Francis Bacon can be considered an early Empiricist, through his popularization of an inductive methodology for scientific inquiry, which has since become known as the scientific method.

In the 17th and 18th Century, the members of the British Empiricism school John Locke, George Berkeley and David Hume were the primary exponents of Empiricism. They vigorously defended Empiricism against the Rationalism of Descartes, Leibniz and Spinoza.

The doctrine of Empiricism was first explicitly formulated by the British philosopher John Locke in the late 17th Century. Locke argued in his "An Essay Concerning Human Understanding" of 1690 that the mind is a tabula rasa on which experiences leave their marks, and therefore denied that humans have innate ideas or that anything is knowable without reference to experience. However, he also held that some knowledge (e.g. knowledge of God's existence) could be arrived at through intuition and reasoning alone.

The Irish philosopher Bishop George Berkeley, concerned that Locke's view opened a door that could lead to eventual Atheism, put forth in his "Treatise Concerning the Principles of Human Knowledge" of 1710 a different, very extreme form of Empiricism in which things only exist either as a result of their being perceived, or by virtue of the fact that they are an entity doing the perceiving. He argued that the continued existence of things results from the perception of God, regardless of whether there are humans around or not, and any order humans may see in nature is effectively just the handwriting of God. Berkeley's approach to Empiricism would later come to be called Subjective Idealism.

The Scottish philosopher David Hume brought to the Empiricist viewpoint an extreme Skepticism. He argued that all of human knowledge can be divided into two categories: relations of ideas (e.g. propositions involving some contingent observation of the world, such as "the sun rises in the East") and matters of fact (e.g. mathematical and logical propositions), and that ideas are derived from our "impressions" or sensations. In the face of this, he argued that even the most basic beliefs about the natural world, or even in the existence of the self, cannot be conclusively established by reason, but we accept them anyway because of their basis in instinct and custom.

John Stuart Mill, in the mid-19th Century, took Hume and Berkeley's reasoning a step further in maintaining that inductive reasoning is necessary for all meaningful knowledge (including mathematics), and that matter is merely the "permanent possibility of sensation" as he put it. This is an extreme form of Empiricism known as Phenomenalism (the view that physical objects, properties and events are completely reducible to mental objects, properties and events).

In the late 19th Century and early 20th Century, several forms of Pragmatism arose, which attempted to integrate the apparently mutually-exclusive insights of Empiricism (experience-based thinking) and Rationalism (concept-based thinking). C. S. Peirce and William James (who coined the term "radical empiricism" to describe an offshoot of his form of Pragmatism) were particularly important in this endeavor.

The next step in the development of Empiricism was Logical Empiricism (or Logical Positivism), an early 20th Century attempt to synthesize the essential ideas of British Empiricism (a strong emphasis on sensory experience as the basis for knowledge) with certain insights from mathematical logic that had been developed by Gottlob Frege, Bertrand Russell and Ludwig Wittgenstein. This resulted in a kind of extreme Empiricism which held that any genuinely synthetic assertion must be reducible to an ultimate assertion (or set of ultimate assertions) which expresses direct observations or perceptions.