In an age where the existence of magical forces is no longer taken for granted, believers in magic are likely to be asked, "How does magic work?".

These are various hypothesis trying to explain what basically cannot be explained (or it would not be called magic anymore).

Natural forces that cannot be detected by science at present, and in fact may not be detectable at all. These magical forces are said to exist in addition to and alongside the four fundamental forces of nature: gravity, electromagnetism, the strong nuclear force and the weak nuclear force.

A mystical power, such as mana, that exists in all things and connects and binds every being in the cosmos. This power is often said to be dangerous to people.

In the mid-19th century Baron Carl von Reichenbach, an accomplished chemist (known for his analysis of creosote, waxy paraffin, and phenol) gave the name Odic force (also called Od [õd] and Odyle) to a hypothetical vital energy or life force. Proponents of the concept suggest that Odic force permeates all living plants, animals, and humans. It took its place in the 19th century as one of many proto-scientific ideas leading towards a unified theory of vitalism. Von Reichenbach coined the name from that of the Old Norse god Odin.

Believers in Odic force state that it resembles the eastern mystical concepts ch'i and prana. However, they regard the Od, not as associated with breath (like ch'i), but mainly with claimed electromagnetic properties.

Intervention of spirits/deities similar to these hypothetical natural forces, but with their own consciousness and intelligence. Believers in spirits will often see a whole cosmos of beings of many different kinds, sometimes organized into a hierarchy.

Manipulation of symbols. Adherents of magical thinking believe that symbols can be used for more than representation: they can magically take on a physical quality of the phenomenon or object that they represent. By manipulating symbols (as well as sigils), one is said to be able to manipulate the reality that this symbol represents.

The principles of sympathetic magic of Sir James George Frazer, explicated in his The Golden Bough (third edition, 1911-1915). These principles include the "law of similarity" and the "law of contact" or "contagion." These are systematized versions of the manipulation of symbols. Frazer defined them this way:

If we analyse the principles of thought on which magic is based, they will probably be found to resolve themselves into two: first, that like produces like, or that an effect resembles its cause; and, second, that things which have once been in contact with each other continue to act on each other at a distance after the physical contact has been severed. The former principle may be called the Law of Similarity, the latter the Law of Contact or Contagion. From the first of these principles, namely the Law of Similarity, the magician infers that he can produce any effect he desires merely by imitating it: from the second he infers that whatever he does to a material object will affect equally the person with whom the object was once in contact, whether it formed part of his body or not.

Concentration or meditation. A certain amount of restricting the mind to some imagined object (or will), according to Aleister Crowley, produces mystical attainment or "an occurrence in the brain characterized essentially by the uniting of subject and object." (Book Four, Part 1: Mysticism) Magick, as defined previously, seeks to aid concentration by constantly recalling the attention to the chosen object (or Will), thereby producing said attainment. For example, if one wishes to concentrate on a God, one might memorize a system of correspondences (perhaps chosen arbitrarily, as this would not affect its usefulness for mystical purposes) and then make every object that one sees "correspond" to said God.

Aleister Crowley wrote that ". . . the exaltation of the mind by means of magical practices leads (as one may say, in spite of itself) to the same results as occur in straightforward Yoga." Crowley's magick thus becomes a form of mental, mystical, or spiritual discipline, designed to train the mind to achieve greater concentration. Crowley also made claims for the paranormal effects of magick, suggesting a connection with the first principle in this list. However, he defined any attempt to use this power for a purpose other than aiding mental or mystical attainment as "black magic".

The magical power of the subconscious mind. To believers who think they need to convince their subconscious mind to make the changes they want, all spirits and energies are projections and symbols that make sense to the subconscious. A variant of this belief is that the subconscious is capable of contacting spirits, who in turn can work magic.

It is very likely, that power comes mainly by suggestion and the focusing of attention. It can be characterized as assertion of the will. Working of magic is often dependent upon being part of a social group which supports the belief. A survey of writings by believers in magic shows that adherents believe that it may work by one or more of these basic principles.

Many more theories exist. Practitioners will often mix these concepts, and sometimes even invent some themselves. In the contemporary current of chaos magic in particular, it is not unusual to believe any concept of magic works.