Rational emotive behaviour therapy ('REBT') views human beings as 'responsibly hedonistic' in the sense that they strive to remain alive and to achieve some degree of happiness. However, it also holds that humans are prone to adopting irrational beliefs and behaviours which stand in the way of their achieving their goals and purposes. Often, these irrational attitudes or philosophies take the form of extreme or dogmatic 'musts', 'shoulds', or 'oughts'; they contrast with rational and flexible desires, wishes, preferences and wants. The presence of extreme philosophies can make all the difference between healthy negative emotions (such as sadness or regret or concern) and unhealthy negative emotions (such as depression or guilt or anxiety). For example, one person's philosophy after experiencing a loss might take the form: "It is unfortunate that this loss has occurred, although there is no actual reason why it should not have occurred. It is sad that it has happened, but it is not awful, and I can continue to function." Another's might take the form: "This absolutely should not have happened, and it is horrific that it did. These circumstances are now intolerable, and I cannot continue to function." The first person's response is apt to lead to sadness, while the second person may be well on their way to depression. Most importantly of all, REBT maintains that individuals have it within their power to change their beliefs and philosophies profoundly, and thereby to change radically their state of psychological health.

REBT employs three primary insights:
While external events are of undoubted influence, psychological disturbance is largely a matter of personal choice in the sense that individuals consciously or unconsciously select both rational beliefs and irrational beliefs at (B) when negative events occur at (A)
Past history and present life conditions strongly affect the person, but they do not, in and of themselves, disturb the person; rather, it is the individual's responses which disturb them, and it is again a matter of individual choice whether to maintain the philosophies at (B) which cause disturbance.
Modifying the philosophies at (B) requires persistence and hard work, but it can be done.

Throughout, the counsellor may take a very directive role, actively disputing the client's irrational beliefs, agreeing homework assignments which help the client to overcome their irrational beliefs, and in general 'pushing' the client to challenge themselves and to accept the discomfort which may accompany the change process.