Chiropractic's early philosophy was rooted in vitalism, spiritual inspiration and rationalism. A philosophy based on deduction from irrefutable doctrine helped distinguish chiropractic from medicine, provided it with legal and political defenses against claims of practicing medicine without a license, and allowed chiropractors to establish themselves as an autonomous profession.

This "straight" philosophy, taught to generations of chiropractors, rejects the inferential reasoning of the scientific method, and relies on deductions from vitalistic first principles rather than on the materialism of science. However, most practitioners currently accept the importance of scientific research into chiropractic, and most practitioners are "mixers" who attempt to combine the materialistic reductionism of science with the metaphysics of their predecessors and with the holistic paradigm of wellness; a 2008 commentary proposed that chiropractic actively divorce itself from the straight philosophy as part of a campaign to eliminate untestable dogma and engage in critical thinking and evidence-based research.

Although a wide diversity of ideas currently exists among chiropractors, they share the belief that the spine and health are related in a fundamental way, and that this relationship is mediated through the nervous system. Chiropractors study the biomechanics, structure and function of the spine, along with what they say are its effects on the musculoskeletal and nervous systems and its role in health and disease.

Chiropractic philosophy includes the following perspectives:

* Holism assumes that health is affected by everything in an individual's environment; some sources also include a spiritual or existential dimension. In contrast, reductionism in chiropractic reduces causes and cures of health problems to a single factor, vertebral subluxation.

* Conservatism considers the risks of clinical interventions when balancing them against their benefits. It emphasizes noninvasive treatment to minimize risk, and avoids surgery and medication.

* Homeostasis emphasizes the body's inherent self-healing abilities. Chiropractic's early notion of innate intelligence can be thought of as a metaphor for homeostasis.

* Straights tend to use an approach that focuses on the chiropractor's perspective and the treatment model, whereas mixers tend to focus on the patient and the patient's situation.

Straights and mixers

Chiropractic is often described as two professions masquerading as one. Unlike the distinction between podiatry (a science-based profession for foot disorders) and foot reflexology (an unscientific philosophy which posits that many disorders arise from the feet), in chiropractic the two professions attempt to live under one roof.

Straight chiropractors adhere to the philosophical principles set forth by D.D. and B.J. Palmer, and retain metaphysical definitions and vitalistic qualities. Straight chiropractors believe that vertebral subluxation leads to interference with an "Innate Intelligence" exerted via the human nervous system and is a primary underlying risk factor for many diseases. Straights view the medical diagnosis of patient complaints (which they consider to be the "secondary effects" of subluxations) to be unnecessary for chiropractic treatment. Thus, straight chiropractors are concerned primarily with the detection and correction of vertebral subluxation via adjustment and do not "mix" other types of therapies. Their philosophy and explanations are metaphysical in nature and prefer to use traditional chiropractic lexicon (i.e. perform spinal analysis, detect subluxation, correct with adjustment, etc.). They prefer to remain separate and distinct from mainstream health care.

Mixer chiropractors "mix" diagnostic and treatment approaches from osteopathic, medical, and chiropractic viewpoints. Unlike straight chiropractors, mixers believe subluxation is one of many causes of disease, and they incorporate mainstream medical diagnostics and employ many treatments including conventional techniques of physical therapy such as exercise, massage, ice packs, and moist heat, along with nutritional supplements, acupuncture, homeopathy, herbal remedies, and biofeedback. Mixers tend to be open to mainstream medicine and are the majority group.