A belief system is a set of mutually supportive beliefs. The beliefs may be religious, philosophical, ideological or a combination of these. Philosopher Jonathan Glover says that beliefs are always a part of a belief system, and that belief systems are difficult to completely revise.

The British philosopher Stephen Law has described some belief systems (including belief in homeopathy, psychic powers and alien abduction) as "claptrap" and said that they "draw people in and hold them captive so they become willing slaves ... if you get sucked in, it can be extremely difficult to think your way clear again".

Jonathan Glover believes that he and other philosophers ought to play some role in starting dialogues between people with deeply held, opposing belief, especially if there is risk of violence. Glover also believes that philosophy can offer insights about beliefs that would be relevant to such dialogue.

Glover suggests that beliefs have to be considered holistically, and that no belief exists in isolation in the mind of the believer. They always implicate and relate to other beliefs.Glover provides the example of a patient with an illness who returns to a doctor, but the doctor says that the prescribed medicine is not working. At that point, the patient has a great deal of flexibility in choosing what beliefs to keep or reject; the patient could believe that the doctor is incompetent, that the doctor's assistants made a mistake, that the patient's own body is unique in some unexpected way, that western medicine is ineffective, or even that western science is entirely unable to discover truths about ailments.

Anthony "Tony" Robbins (born February 29, 1960) is an American self-help author and motivational speaker. He became well known through his infomercials and self-help books, Unlimited Power: The New Science Of Personal Achievement and Awaken The Giant Within. Robbins writes about subjects such as health and energy, overcoming fears, persuasive communication, and enhancing relationships. Robbins began his career learning from many different motivational speakers, and promoted seminars for his personal mentor, Jim Rohn. He is deeply influenced by neuro-linguistic programming and a variety of philosophies.

Robbins's work has been featured in major media including Time, Newsweek, Fortune, Forbes, Life, GQ, Vanity Fair, Business Week, Tycoon and Success magazines, the CBS Evening News, NBC News, ABC's Prime Time Live, Fox News, CNN and A&E as well as newspapers, radio programs, and Internet media worldwide. Robbins has been mentioned or featured in 15 major motion pictures, including a cameo role a romantic comedy film Shallow Hal, starring Gwyneth Paltrow, Jack Black, and Jason Alexander. In 2007, he was named to Forbes magazine's "Celebrity 100" list.