Science often treats concepts and practices from spirituality and alternative medicine with great skepticism, often referring to them as 'quackery' or 'pseudo-science'.
Modern science treats the human body essentially as a Newtonian machine, with localised causal-effect dynamics that can be separated in different components and analysed individually. Modern medicine often fails to explore the holistic functioning of the body and mind as a whole, and in particular the effect of the mind on the body, as well as the variety of intricate effects that one localised action can have on the whole. These effects are usually merely discarded as placebo and as side effects, in spite of their significance, and no more concerned is given them. This is a bit of a restrictive approach, as both these comprise a significant factor in the state of patients. Yet the choice of ignoring the placebo effect in particular is maintained in the way that every and each experiment is tailored precisely to exclude it, rather than to study or understand it it, using standard blind and double blind study procedures.
The placebo effect however has been shown to have very significant effects on the physical and mental state of patients, in some cases even more significant than any medical intervention (https://www.youtube.com/watch?v=LWQfe__fNbs). Side effects can also be very significant and can create a variety of unwanted symptoms in patients who take medication.
Spirituality and alternative medicine, in my view, are nothing more than attempts to understand and use these effects in spite of the lack of scientific interest in them. Spirituality is nothing more than the study of the way the mind affects the body as well as itself and the external reality, through direct observation of consciousness (emotions, feelings, states of mind, in other words experience). As there is no yet defined scientific language or method available to describe such effects, and as people who dwell into these areas of study often do not have a strong scientific background, a particular terminology is usually adopted in these practices.
It is my opinion from my personal experience and studies that we need both modern medicine as well as an understanding and way to use the placebo effect, as they are both effective in treating a person, in different, complementary ways. They should be integrated as relevant and complementary healing practices.
But before I go on, let me give a few examples to showcase what I mean when I claim that spirituality is the study of how the mind affects the body and itself.
Let's take, for instance, the case of colour therapy, a well known case of 'pseudo-science' by the scientific community. If you tap into your personal and general experience, you can easily recall various connections between certain colours and certain emotions or states. Red, for instance, is usually associated with feelings of passion and love, whereas blue is associated with feelings of peace. Where do these associations stem from? If these associations didn't exist, marketing specialists and artists would not bother using different colours to deliver various types of (subconscious) emotional messages to their audience. So if science does not have an explanation for these associations, where do they stem from? Are they purely random?
The perception of different colours activates slightly different areas of the brain depending on the specific colour. Suppose that because of the way the brain is wired and structured physically, the areas of the brain that are activated by the colour red are slightly closer or more connected to the parts in the brain that are activated by emotions of passion, whereas those activated by the colour blue are closer or more connected to circuitry in the brain activated by emotions of tranquillity. Then it would be deducible, that while we are exposed to the red colour, our passionate emotional states are more easily triggered than the more tranquil ones, and vice-versa if we are exposed to the blue colour. Of course this is pure speculation: I don't actually know which colour activated areas of the brain are closer or more connected to which emotionally activated areas, however this is a very plausible and in fact reasonable explanation for our perceived association between different colours and emotions.
That our brain associates different, often unrelated things is certainly not a new concept at all. It is well known fact in neurology that synaptic connections between neural clusters are strengthened with repeated stimulation, indeed that is how most learning occurs (G. Edelman). The very famous Pavlov's dog's experiment is just a small example of such formed connection between completely unrelated things - the ring of a bell and food. People whose brain lack certain commonly present divisions are even able to experience sounds as colours and vice-versa (https://en.wikipedia.org/wiki/Synesthesia). This shows that there are certain structural connections and arrangements between various ideas in our brain that are not always obviously related.
Another way we can see how colours can have an effect on our mind is simply by virtue of our preference of certain colours over others. If colours were purely objective states with no effect whatsoever on our mind other than the perception of the colour itself, it would make no sense to prefer a colour over another. What would you prefer about it? Indeed there must be some kind of experience of greater pleasantness associated with certain colours than others. This experience can come from the above mentioned - more universal and structural - kinds of associations in the brain, or it can derive from very personal associations. For instance the experience of a particular dreadful teacher we had in our childhood who always wore purple suits might make us slightly repelled by that colour. Or the experience of our childhood home being painted green might make us feel more attracted to the colour green. All sorts of associations are possible here. The point is that colours do have an effect on our state of mind and experience, and this effect can be used to our advantage, weather science is interested in studying it or not.
Let's take another, more complex example. Many of you I'm sure have heard of tarot cards. Many fortune tellers claim the ability to use those cards to tell us things about ourselves or our future. Although these claims might seem to be delusional at best, there is actually a validity behind them that I will explain here. It is a well established discovery in psychology that only a small part of our mental processes are consciously experienced, the majority is unconscious. For instance the functionality of all our organs happens entirely under our conscious awareness, so does the sleeping system and in general the sympathetic system in our body. We certainly do not need to be aware of breathing in order to do so, nor to digest food. Further than that, all learned behaviours are for the most part unconscious. You don't need to consciously make an effort to stay in equilibrium while you walk, nor do you need to be consciously aware of the way your tongue is placed in your mouth to produce different sounds and words: your subconscious mind does that for you. You only needed to be conscious during the process of learning to walk or talk, but once the behaviour has been internalized, it is underneath your level of consciousness. The same goes when riding a bicycle or playing the piano. If you really want to understand the degree to which this behaviour has been internalized by your subconscious mind, try for once to ride a reverse bicycle (http://engineering.unl.edu/backwards-bike-helps-engineering-students-learn-new-ways-thinking/): you will fail miserably. To be able to do so you'll have to tap into your subconscious bicycle-riding programs and rewire them again. Once you have learned to ride such a bicycle, again you'll encounter the same difficulty if you want to re-learn to ride a normal bicycle and so on. Another layer of our mind that is unconscious are learned belief systems, prejudices, fears and all sorts of associations. For instance, growing up in a racist country we might have learned to subconsciously associate a black person with fear. Now, given the amount of information that is stored in our brain and that we are unaware of, it is obvious that it would come to our advantage to be able to tap into some of that information and in particular change the associations that are detrimental (such as the race one mentioned above). How do we do that?
That's where tarot cards come in. What happens when we pick cards from a deck of a colourful, variety of shapes and figures and observe them? What sort of reactions do we experience as a result of observing a particular card? That will depend, again, largely on the universal subconscious associations in our brain as well as our subconscious personal associations. I'll give you a very specific example from my personal experience to illustrate. Suppose you grew up with a wealthy father who used the power given by his money to control and manipulate people. Growing up you might have internalized the association between wealthy people and something negative. Now, let's say that you pick a card and it so happens to illustrate a wealthy king sitting on a throne with an air of austerity (this actually happened to me in real life). This card might immediately provoke a negative reaction from you as you are repelled by the look of superiority in the wealthy king in the card. Let's say that Mary, on the other hand, grew up in poverty, and as a child often received aid from wealthier people. She therefore learned to associate wealth as something very desirable. Her reaction to that card might be very different, she might feel a sensation of attraction towards the figure of the wealthy king.
Thus, our reactions to certain figures and cards, can be used to trace back certain associations that are present in our subconscious mind, to understand them and perhaps to change them. This is essentially what tarot cards are used for, when used appropriately.
Let's take another example: the chakras. According to spiritual philosophies, the chakras are different points in our bodies associated with certain emotions, physical states and states of energy and wellbeing in general. For instance the solar sacral chakra is associated with sexuality and lower abdomen, as well as with creativity and the colour orange. Again, these concepts may seem unrelated, yet many people experience a connection between their sexuality and their creativity, as well as the associated parts in the body. Some of these connections are physical (sexual organs and sexuality), and some may again stem from the brain's structure as explained above. Understanding these connections and working with them can be very useful. One could imagine designing experiments to test these connections as well, for instance by monitoring various indicators of sexual satisfaction and creativity in a group of individuals. Or perhaps using MRI scans to see which parts of the brain are active during sexual activity, creative activity and while perceiving the colour orange. Although science has not yet explored these connections and possible explanations, they remain a useful tool for healing and understanding oneself.
Another great example are meditation techniques. I say it is a great example because these practices involve solely a mental activity and nothing else, thus functioning as a perfect showcase for the way the mind affects the body and itself. Although many meditation practices have been used for thousands of years already by spiritual schools, science is only now starting to explore and validate their significant effects on the body and mind (http://news.harvard.edu/gazette/story/2012/11/meditations-positive-residual-effects/, https://www.washingtonpost.com/news/inspired-life/wp/2015/05/26/harvard-neuroscientist-meditation-not-only-reduces-stress-it-literally-changes-your-brain/?utm_term=.c48919221a3b).
There are many other examples, but the point I want to make is that there is a practical usefulness to these practices that explore the way our mind affects our body, our experience and our interaction with reality, even though these effects are in the realm of what science - for a lack of a deeper understanding of this phenomenon - simply classifies with the general term 'placebo'. It would be great if science dedicated more effort into studying these phenomena in depth, rather than discarding them a priori. Perhaps there isn't enough research in these areas due to the lack of monetary gain from this kind of knowledge. Indeed what good would it do the pharmaceutical industry if a person learns to heal themselves through their thinking? It would also be great if spiritual people learned enough science to be able to use a terminology that is less confusing and more scientifically understandable when describing such phenomena. For instance, instead of "Prana", "Universe", "Manifesting", we could talk about "helpful outside stimulation", and "the subconscious mind with its external interaction", "the effect of thoughts on our subconscious actions" to be clearer. I cringe every time I hear a spiritual person using words stolen from quantum physics to describe spiritual phenomena, thus blatantly displaying their utter ignorance on the subject. Of course, as in every realm, some people do take advantage of these weaknesses and confusions to practice 'pure quackery', just as there exist scientists who abuse the statistical method and publication system to select which results they want to publish, resulting in false science. However dismissing these methods simply because we still don't understand them fully is a declaration of chosen ignorance and nothing more.