On the face of it subjective idealism appears to have frighteningly little content. To briefly summarize it, what does subjective idealism propose?

Firstly, all that can be known and experienced is a product of one’s own mind.

Secondly, one’s own mind cannot be understood in terms of one or any set of its products.

Thirdly, all the specifics of knowledge and experience are volitional or subjective. (Volitional and subjective are synonyms here. They mean the same thing.)

And that’s about it.

So isn’t this rather thin? This philosophy tells us nothing about the color of the sky, or whether or not there even is such a thing as the sky. It tells us nothing about the shape and the size of any body. It tells us nothing about whether or not music exists and which sort of music is best. It tells us nothing about space and time even! It tells us nothing about the number of sentient beings: is there just one or are there many? Although it does suggest there is at least one sentient being: the reader. It tells us nothing about how best to relate to experience, including when we experience ourselves to be in the presence of what we believe to be other sentient beings.

Even from the POV of aesthetics, subjective idealism is so abstract, that to find beauty in it requires a very particular sense of beauty tending toward maximum parsimony and simplicity. So there is a possibility of someone studying it for its aesthetic beauty, but I want contend it won’t be that for most people who might want to study it.

So what might the utility be?

Hypothetically a subjective idealist can hold any sort of axiomatic commitment(s). A subjective idealist can even hold a commitment to the axioms of physicalism. If so, what is the difference then between a subjective idealist holding a commitment to physicalism and a bona fide physicalist? The difference is that a bona fide physicalist doesn’t feel that the postulates of physicalism are a choice. A physicalist will feel as though the truth of physicalism somehow impresses itself upon the mind whether one likes it or not. So in other words, in the language of subjective idealism, a physicalist is someone who has othered or disowned one’s own commitment to physicalism and is no longer consciously aware of it.

And these sorts of othered commitments can be the strongest ones. These are the commitments that are tacit, unspoken, default, instintinctual. They’re unspoken because they’re so “obvious” that they don’t need to be mentioned. They’re so widely and pervasively assumed in the subjective sphere of one’s own mind that one needn’t discuss or think about them. And there is a lot of power in this. Allowing one’s own commitment to become tacit and implicit to the greatest possible degree makes the experiential consequences of that commitment very stable and densely apparent.

And now we can understand why someone might want to study subjective idealism.

Simply put contemplating subjective idealism returns a sense of personal conscious choice to one’s deepest core commitments. And this in turn opens up the possibility of making a change at the most profound level of one’s relationship to one’s sphere of experience.

This suggests a strong theme of discontentment at the deepest level of one’s phenomenal reality. Why would anyone even think about changing one’s fundamental axioms about phenomenal reality if the person considered them even remotely workable?

And it also suggests that one is considering alternative commitments. So if not physicalism, what then? I suggest that subjective idealism itself is too thin, too abstract, and so I don’t think it can replace physicalism by itself. Becoming consciously aware of one’s commitment to physicalism weakens that commitment, but if we’re not going to contemplate any alternatives, there is no point in weakening one’s perception of physicalism.

Another thing to consider is, do we want to jump to just one long-term alternative? Or do we want to develop a more complex system of relating to one’s experience through the lens of more than one commitment in parallel?

And if more than one, then how many? Two? Three? More?

There are so many possibilities here that I cannot even imagine them all. I just intuitively feel that the choice here is mindblowingly wide open. My own ready imagination is restricted by prior expectations. What I might be able to imagine tomorrow might be different from what I can imagine today. What one can imagine in principle is different from what can readily imagine right now.

One choice that’s obvious to me personally is going for subjective idealism plus a dual combination of physicalism and solipsism. So one way to exercise this is to relate to one’s experience as a physicalist during most typical activity, but to relate to one’s experience as a solipsist during a magickal ritual. There are many possibilities, and this is only one, just as an example. Another possibility is to relate to one’s experience as a physicalist when comfortable, but in times of crisis relate to one’s experience as a solipsist. An obligatory car metaphor is that you use cruise control when the driving is safe, but take manual control of the car when it’s potentially dangerous. So this presupposes being able to shift one’s manner of relating when necessary, and this implies that one has to be aware that even such fundamental and axiomatic commitments as physicalism are voluntary, and this is exactly what studying subjective idealism can accomplish.

Other slightly less obvious possibilities can include: living with the ability to switch on demand between animism and solipsism. Jumping to full-time animism, where subjective idealism is only a realtively brief transitional period necessary to accomplish the jump. One can even live with the ability to switch between physicalism, animism and solipsism. Or one can live with the ability to switch between animism and physicalism under the framework of subjective idealism.

So it seems to me that if one wants to be able to switch rapidly between two or more sets of fundamental axioms regarding how to relate to one’s experience, then subjective idealism is helpful on a long term basis.

And if one wants to just switch from physicalism to animism, then subjective idealism can be helpful as a transitioning phase, after which one can become a bona fide animist.

Another possible reason to study subjective idealism is to gain the ability to update significant details in your otherwise favorite system of core belief. So with the aid of subjective idealism one could shift one’s commitment from physicalism A to physicalism B. As an example, maybe in physicalism A faster than light travel is impossible, and in physicalism B it is possible.

There is another powerful reason to never become bona fide anything other than a subjective idealist. And that is, you may realize that no set of axioms about how to best relate to your subjective experience is going to be desirable forever. Since you anticipate the need to switch at some point when you grow tired of a certain way of life, you may want to keep yourself ready for such change by having never allowed yourself to get to the point where some core metaphysical commitments have become instinctive and unconscious. That way if you realize you may want to live 30 human lifetimes as an animist, you could do that, and then on your 30th lifetime you could switch to say physicalism without any particulalry arduous spiritual effort, provided you kept yourself a subjective idealist with a commitment to animism and never became a bona fide animist.