Dualism is a traditional belief that we are all made up of a physical body and a spiritual body. We believe that the spirit inhabits the body until death.
Teachers routinely use the analogy about a hand in a glove:
Explain that in this example the glove represents the physical body and the hand represents the spirit. When the spirit enters the body, the body can live, work, and act.
This analogy implies that the spirit is responsible for controlling the movements of the body. But nobody really has a good explanation for how the spirit interacts with the physical body. In order to affect physical muscles or even physical neurons, physical energy must be applied. And if physical energy is present, then it can be measured by scientific instruments just like any other physical events. But we usually think of the spirit as something that can’t be measured. In fact, any part of the spirit that can be observed physically should not be considered to be spiritual, by definition.
There is a different analogy that I like better, of a masterpiece painting. The painting is physically made up of oils and a canvas. But people looking at the painting can feel something deeper in it. The painting can have a spiritual presence. I think you could say that the painting wouldn’t be alive without that spirit. As another example, we recognize sacred places by the spiritual qualities attached to them.
Likewise, I think that it is our spirits that give our lives deeper meaning. Our physical bodies are just the machines, where pain is sensed and muscles are flexed. Our spirits inhabit the machinery, without interfering with it. Nothing from the spiritual realm ever enters the physical realm, nor does it need to. Even our power to make decisions is seated solely in our physical brains. This belief is called epiphenomenalism, an unpopular version of dualism.
One criticism of this belief is that it implies that spirits are not capable of appearing in the physical world or performing physical miracles. Many people would assume that this makes spirits inconsequential. As long as we have faith, though, the spiritual realm remains just as relevant as ever. The purpose of well grounded spiritual beliefs is to discover life’s deeper meaning, not to solicit physical miracles.
Many people already believe that God conforms to the laws of nature when performing miracles. For example, when Moses parted the Red Sea, God summoned a strong wind to hold the waters back. According to epiphenomenalism, physical miracles are always realized by such natural means. Epiphenomenalism gives people less reason to sensationalize physical miracles, because a rational explanation is presumed to exist. Instead, people have reason to seek out a spiritual meaning for the miracles.
As a thought experiment, imagine that a camera had been set up on the Mount of Transfiguration. Consider what it would have recorded when Moses and Elias appeared. Joseph Smith said that we cannot behold spiritual matter with our physical eyes. A camera is all physical, so it would be completely blind to the heavenly visitors. The angels were spiritually present, but not physically visible. As we know from the scriptures, that did not detract from the magnificence of the vision because the disciples exercised their faith and used their spiritual eyes. (Also compare Moses 1:11 and 2 Nephi 2:4 and the dramatic account of the invisible chariots of fire protecting Elisha).
Therefore, every spiritual manifestation is a trial of faith. One who has faith can see spiritual miracles. One without faith can see only physical events, and all those could be explained rationally. Without faith, the entire universe looks materialistic and the presence of God cannot be detected. With faith, the same physical universe is clothed in divine purpose.