Behaviorism

Behaviorism or Behaviourism, also called the learning perspective, is a philosophy of psychology based on the proposition that all things which organisms do — including acting, thinking and feeling—can and should be regarded as behaviors.The school of psychology maintains that behaviors as such can be described scientifically without recourse either to internal physiological events or to hypothetical constructs such as the mind. Behaviorism comprises the position that all theories should have observational correlates but that there are no philosophical differences between publicly observable processes (such as actions) and privately observable processes (such as thinking and feeling).
From early psychology in the 19th century, the behaviorist school of thought ran concurrently and shared commonalities with the psychoanalytic and Gestalt movements in psychology into the 20th century; but also differed from the mental philosophy of the Gestalt psychologists in critical ways.Its main influences were Ivan Pavlov, who investigated classical conditioning, Edward Lee Thorndike, John B. Watson who rejected introspective methods and sought to restrict psychology to experimental methods, and B.F. Skinner who conducted research on operant conditioning.
Versions
There is no classification generally agreed upon, but some titles given to the various branches of behaviorism include:

Classical: The behaviorism of Watson; the objective study of behavior; no mental life, no internal states; thought is covert speech.
Methodological: The objective study of third-person behavior; the data of psychology must be inter-subjectively verifiable; no theoretical prescriptions. It has been absorbed into general experimental and cognitive psychology.
Radical: Skinner's behaviorism; is considered radical since it expands behavioral principles to processes within the organism; in contrast to methodological behaviorism; not mechanistic or reductionist; hypothetical (mentalistic) internal states are not considered causes of behavior, phenomena must be observable at least to the individual experiencing them. Willard Van Orman Quine used many of radical behaviorism's ideas in his study of knowing and language.
Logical: Established by Oxford philosopher Gilbert Ryle in his book The Concept of Mind (1949).
Teleological: Post-Skinnerian, purposive, close to microeconomics.
Theoretical: Post-Skinnerian, accepts observable internal states ("within the skin" once meant "unobservable", but with modern technology we are not so constrained); dynamic, but eclectic in choice of theoretical structures, emphasizes parsimony.
Biological: Post-Skinnerian, centered on perceptual and motor modules of behavior, theory of behavior systems.
Inter behaviorism: Founded by J. R. Kantor before Skinner's writings and currently worked by L. Hayes; E. Ribes; and S. Bijou. centered in the inter behavior of organisms, field theory of behavior; emphasis on human behavior.