Understanding the philosophical foundations of cognitive–behavioural therapy (CBT) is vital to drive theory and research forwards and to effectively conduct therapy using varied methods and techniques from different CBT models that may be rooted in distinct philosophical tenets. In the evolution of CBT as the most empirically validated form of psychotherapy, each of its three waves (behavioural therapy, cognitive therapy and acceptance-based therapies) has brought unique contributions to improve its effectiveness. Although some of the philosophical assumptions underlying the different CBT waves may be considerably dissimilar, in this clinical reflection I review the distinctive and cross-cutting features of such backgrounds, while suggesting a conciliation of epistemological perspectives that is capable of informing the practice of CBT in a consistent manner.

What sorts of things undergird a person's character and what does the answer tell us about the person's relationship to her body, her environment, and the people who surround her? For the purpose of ascribing virtue, vice, and character, what are the boundaries of the person? Traditionally, philosophers have accepted mentalism, the view that only mental features are relevant to character. Even philosophers inclined to say that character is partially constituted by nonmental features would be inclined to accept skindividualism: a person's virtue must involve a disposition that is wholly grounded by features inside the person's skin. Drawing from arguments in the philosophy of mind and data from social psychology, I argue that skindividualism is wrong. Virtues can be extended, in the sense that the grounds for a person's virtues might not be inside that individual's skin. If this is the case, persons are not skindividuals.

Most of what we believe comes to us from the word of others, but we do not always believe what we are told. We often reject thinkers’ reports by attributing biases to them. We may call this debunking. In this essay, I consider how debunking might work and then examine whether, and how often, it can help to preserve rational belief in the face of disagreement.

The major contributions of operationism have been negative, largely because operationists failed to distinguish logical theories of reference from empirical accounts of language. Behaviorism never finished an adequate formulation of verbal reports and therefore could not convincingly embrace subjective terms. But verbal responses to private stimuli can arise as social products through the contingencies of reinforcement arranged by verbal communities.

In analyzing traditional psychological terms, we need to know their stimulus conditions (“finding the referent”), and why each response is controlled by that condition. Consistent reinforcement of verbal responses in the presence of stimuli presupposes stimuli acting upon both the speaker and the reinforcing community, but subjective terms, which apparently are responses to private stimuli, lack this characteristic. Private stimuli are physical, but we cannot account for these verbal responses by pointing to controlling stimuli, and we have not shown how verbal communities can establish and maintain the necessary consistency of reinforcement contingencies.

Verbal responses to private stimuli may be maintained through appropriate reinforcement based on public accompaniments, or through reinforcements accorded responses made to public stimuli, with private cases then occurring by generalization. These contingencies help us understand why private terms have never formed a stable and uniform vocabulary: It is impossible to establish rigorous vocabularies of private stimuli for public use, because differential reinforcement cannot be made contingent upon the property of privacy. The language of private events is anchored in the public practices of the verbal community, which make individuals aware only by differentially reinforcing their verbal responses with respect to their own bodies. The treatment of verbal behavior in terms of such functional relations between verbal responses and stimuli provides a radical behaviorist alternative to the operationism of methodological behaviorists.