Occasionalism is a concept that attempts to relate the idea of causation to the relationship of the body and the mind. When approached from a theological point of view, occasionalism has to do with the interaction between the physical body and the spirit, which is understood to inhabit the body. Occasionalism presupposes that without some type of force initiating the interaction between the body and the mind, the interaction would never take place and the resulting actions would never come to pass.
As a philosophical and theological theory, occasionalism has been around since at least the 9th century AD. While each approach agrees that some type of force initiates the initial engagement of mind and body, various schools of thought branch off from this common point. For some, not only is the initial force that causes the interaction known as God, but also that all subsequent actions that result from that union of mind and body are caused by God.
To the occasionalist who approaches the theory from a theological standpoint, the actions of God become the source for all outcomes. Thus, if fire is placed in close proximity to paper, the paper is burned by God, not by the fire. This means that all actions are within the perfect will of God, since Deity is the source of all action or cause. Opponents of occasionalism tend to note this approach to the interaction between mind and body negates the principle of free will or agency, which supposes that among the gifts of God to humanity is the privilege of making individual choices and being responsible for the outcomes.
Within the broad scope of occasionalism, the initiating force is not in any way inhibited by humanity. However, the force may be governed by either laws that are unknown to humankind or by laws that are self-imposed by the force itself. There is also a companion theory known as occasional causation, even allows for the entry of a third element of causation into the mix, thus further distancing cause and effect as understood by many persons in the modern world.