Radical behaviorism was pioneered by B. F. Skinner and is his 'philosophy of the science of behavior.' It refers to the philosophy behind behavior analysis, and is to be distinguished from methodological behaviorism—which has an intense emphasis on observable behaviors—by its inclusion of thinking, feeling, and other private events in the analysis of human and animal psychology. The research in behavior analysis is called the experimental analysis of behavior and the application of this field is called applied behavior analysis (ABA), which was originally termed 'behavior modification.' Radical behaviorism was pioneered by B. F. Skinner and is his 'philosophy of the science of behavior.' It refers to the philosophy behind behavior analysis, and is to be distinguished from methodological behaviorism—which has an intense emphasis on observable behaviors—by its inclusion of thinking, feeling, and other private events in the analysis of human and animal psychology. The research in behavior analysis is called the experimental analysis of behavior and the application of this field is called applied behavior analysis (ABA), which was originally termed 'behavior modification.' Radical behaviorism inherits from behaviorism the position that the science of behavior is a natural science, a belief that animal behavior can be studied profitably and compared with human behavior, a strong emphasis on the environment as cause of behavior, and an emphasis on the operations involved in the modification of behavior. Radical behaviorism does not claim that organisms are tabula rasa whose behavior is unaffected by biological or genetic endowment. Rather, it asserts that experiential factors play a major role in determining the behavior of many complex organisms, and that the study of these matters is a major field of research in its own right. The most precise way to describe radical behaviorism as 'radical' is to understand that instances such as evolution and cell division are occurrences that just happen. There is no third party that assists in this transformation; they can, however, be explained by other naturally occurring events. They should not try to be explained through objects that are not tangible, e.g., ghosts or inner entities. Radical behaviorists therefore conclude that naturally occurring events may be examined in relation to our past and present environments through the effect they have on human beings. Although there are many criticisms of Skinner's work, many textbooks and theorists like Noam Chomsky label Skinnerian or radical behaviorism as S–R (stimulus–response, or to use Skinner's term, 'respondent'), or Pavlovian psychology, and argue that this limits the approach. Although contemporary psychology rejects many of Skinner's conclusions, his work into operant conditioning which emphasizes the importance of consequences in modifying discriminative responses is useful when combined with current understandings about the uniqueness of evolved human thought over other animals. Many textbooks argue that radical behaviorism maintains the position that animals (including humans) are passive receivers of conditioning, failing to take into account that: Radical behaviorism is often dismissed as logical positivism. Skinnerians maintain that Skinner was not a logical positivist and recognized the importance of thinking as behavior. This position is made quite clear in About Behaviorism. A clearer position for radical behaviorism seems to be the movement known philosophically as American pragmatism. For a review and summary of Skinner's book Verbal Behavior see the article Verbal Behavior.