Yes. I found them very useful for understanding myself. They confronted me with many unpleasant (and pleasant) but important parts of my life and feelings that I was in denial of or just couldn't experience in ordinary consciousness. They helped me gain a lot of insight in to myself and in to the world.
Another benefit was shaking my certainties about what the world was really like. Up to my first psychedelic experience, I felt pretty comfortable in the world (not that I had a pleasant childhood or life or anything, but I did feel I knew what the world was like, and how to get around in it). Psychedelics radically changed that. Even though I'd read a lot about them before I tried them, and was intellectually prepared for what I experienced, actually experiencing it was a different matter entirely. It's like reading about sex vs actually having sex. Reading about being in love vs actually being in love. There's no comparison.
Likewise, on psychedelics, suddenly I was not in Kansas anymore (metaphorically speaking). I learned that reality could be very different from what I take it to be in ordinary consciousness. And, while in an altered state of consciousness, what I experience could feel "even more real than real". This made me interested in finding out what reality was really like (if that's possible), and led me to become interested in and study philosophy, psychology, and religion.
My psychedelic experiences made me much more laid back, less dogmatic, and more accepting of other people and other views of the world. It also helped a lot with empathy. During a psychedelic experience, I became much more sensitive to my own body, my own feelings, the feelings of people around me, even the feelings of animals and even inanimate objects, which could become animate or even a part of me. I experienced the feeling of being one with everything.
After coming back to ordinary consciousness, those feelings subsided or disappeared entirely. Objects certainly became inanimate again. Still, the thought of the possibility that they were actually animate, and especially the possibility that things like trees might have feelings -- or at the least that I should respect them more than I do, or that they may "know" or "understand" more than I usually give them credit for, or be able to act in ways that I'm not normally aware of remained. And I think I am generally more sensitive towards the feelings of other people now, especially if they are in some sort of distress.
I came to be open to the possibility that there is a god or gods, or at least some sort of sacred reality beyond the one I had access to in ordinary consciousness. I did have experiences where I communicated with various entities and gods. Whether this was real or imaginary I can't say. But I am now more open to the possibility that something like that could be real, and I am more understanding of those people who have had profound mystical experiences or experiences of meeting or talking to God/gods.
Now, I can't give exclusive credit to psychedelics to changing my views on all of these things. Transitioning to my present views on these subjects took a long time, and my psychedelic experiences took place a very long time ago. But they opened the door and showed me the way on many of these things. How "practical" these insights and attitudinal changes have been would depend on what you mean by "practical". They certainly have been profound and important to me. But I can't say I came up with a new invention (as some people have) on psychedelics. Nor did I solve a math problem using them. They didn't make me a better coder. But they were very valuable.
Some studies have actually been done on using psychedelics to enhance creativity. If you are interested, I recommend reading James Fadiman's "The Psychedelic Explorer's Guide", and Oscar Janiger's "LSD, Spirituality, and the Creative Process".
On a humbler note, meditation has helped me to achieve calm (at least while I'm meditating and for some hours afterwards). I view that as a very practical effect.
"I would also like to suggest substituting the word "altered" with "disturbed". Would you mind telling me your thoughts on this (whether in connection with the above question, or not)?"
I don't like using the word "disturbed" for these states. Certainly, sometimes when in these states one can be confronted with visions or feelings that one finds disturbing. Aldous Huxley titled a book of his about psychedelics "Heaven and Hell", and that is sometimes quite an appropriate description of some of the more extreme experiences that one can have on psychedelics or in other non-ordinary states of consciousness. However, they are not always hellish, nor always heavenly. They can be quite unpredictable (especially when used in a haphazard, uninformed, or destructive way). I would agree that those states are non-ordinary -- in that they differ from the ordinary state of consciousness most of us inhabit during our waking lives. But to paint them all indiscriminately with the pejorative term "disturbed" is to misunderstand their nature.
It's also a bit arrogant to put ordinary consciousness up on a pedestal as if it was the ultimate and best form of consciousness and the rest were lacking, wrong, or immoral in some way. Many Buddhists and Hindus would certainly disagree with anyone who tried to claim that the enlightened state of consciousness was "disturbed". From their perspective, it is the ordinary state of consciousness which is "disturbed", and the enlightened state of consciousness that is healthy. Who are we to insist otherwise?
While I don't want to categorically disparage having different experiences, even those that are drug induced... the notion that inanimate objects and even trees have feelings is fundamentally unsound.
If that is a result of your drug-use experience, then I might argue that you have reduced your brain's ability to align itself with experimental reality.
Just like a dieter on fen-phen can lose weight but damage his heart; please don't disregard the possibility that you can have an interesting experience but damage your mind.
It may seem unsound from the perspective of ordinary waking consciousness, and certain materialistic, physicalist, or naturalistic philosophies.
But it seems quite sound from the perspective of many non-ordinary states of consciousness, animism, panpsychism, pantheism, panentheism, various types of shamanism and religions which hold animistic, pantheistic, or panentheistic beliefs.
Now, you may argue that there isn't any or enough evidence to support animistic beliefs. But then the question becomes one of what evidence do you accept. Do you accept the evidence of your own senses while in a non-ordinary state of consciousness? If not, why not? Do you accept as evidence the communication you or others may have had with what you or they consider spirits of other worlds? Do you accept the evidence of sacred writings? Etc..
Perhaps you don't. But is there an empirical reason for not counting this as evidence? It's not like you can "scientifically measure" which criteria are "better". Even if you could, there's the question of whether something that's "scientific" should be chosen over something that isn't. And whatever you chose, others would be free to disagree with you.
So, "sound" or "unsound"? It all depends on your point of view.
Anyway, I'm not saying I'm convinced in ordinary waking consciousness that trees or inanimate objects have feelings. I'm just open to the possibility. Anything is possible, and I'm ok with that. I didn't use to be. I used to be quite dogmatic in clinging to what I considered to be a "scientific" and materialistic world view.
Having psychedelic experiences and learning more about philosophy helped me to question these strongly held beliefs. I don't know if I've found any answers, but I am more open to the possibility that reality is not necessarily the way it appears or the way I think it to be. It could be some other way. I could be wrong. What I think "sound" could be "unsound", and what I think "unsound" may in fact be "sound". Or maybe there's no way it is at all. Who knows? Who is to say? I'm certainly no authority.
 - https://en.wikipedia.org/wiki/Materialism
 - https://en.wikipedia.org/wiki/Physicalism
 - https://en.wikipedia.org/wiki/Naturalism_(philosophy)
 - https://en.wikipedia.org/wiki/Animism
 - https://en.wikipedia.org/wiki/Panpsychism
 - https://en.wikipedia.org/wiki/Pantheism
 - https://en.wikipedia.org/wiki/Panentheism
 - https://en.wikipedia.org/wiki/Shamanism
Excellent, doctrines do tend to be self-contained. IF X, THEN Y. In the mean time, I bring up an important fact: we have always depended decisively on how well we coordinated our ideas with reality, for the purpose of achieving technological efficacy. In this light, the doctrines you enumerated are undesirable. Judging by the rate of success, the former, scientific doctrines you enumerated are more workable and, as such, preferable for the purpose of adjustment to the conditions of empirical life.
> Do you accept the evidence of your own senses while in a non-ordinary state of consciousness? If not, why not?
We accept evidence that is reproducible. I will stop here and not answer the other questions that you followed with, out of politeness.
> So, "sound" or "unsound"? It all depends on your point of view.
> I'm just open to the possibility. Anything is possible, and I'm ok with that. I didn't use to be. I used to be quite dogmatic in clinging to what I considered to be a "scientific" and materialistic world view. [...] Who knows? Who is to say? I'm certainly no authority.
Take much care to ensure that you are not merely being open, like a scientist is to new evidence and a better "map" for the "territory"; but rather that you are doubting everything. And as someone once eloquently put it, there are two ways to glide easily through life: to believe everything, and to doubt everything – both ways save us from thinking. (There's also another less polite quote about being open minded)
That aside, I think you have gathered an extraordinary amount of very interesting knowledge in your pursuits, and I think that in itself was as incredibly useful affair.
Take much care to ensure that you are not doubting everything, instead of being merely open, like a scientist is to new evidence and a better "map" for the "territory". As someone once eloquently put it, there are two ways to glide easily through life:
...if you say so :)
> But to paint them all indiscriminately with the pejorative term "disturbed" is to misunderstand their nature.
I meant the following definition for "disturbed":
interfere with the normal arrangement or functioning of
Sorry, I suppose I should have made it clear. I can see now why I need to be careful using this word. So to return, I connected to the fact that drugs are an intoxicant, perturbing the natural functioning of the nervous system. Using them to achieve a desirable result is... well, let us be polite: it won't become an acceptable form of "treatment". Their unpredictable nature that you mentioned is essentially the strongest argument in this debate.
> It's also a bit arrogant to put ordinary consciousness up on a pedestal as if it was the ultimate and best form of consciousness and the rest were lacking, wrong, or immoral in some way.
No, it's just logically self-contradictory to expect that by perturbing a system you may improve its behaviour. Any argument you may formulate in those terms should and will be discarded. As for other possible arguments in favour of drug use... well we only have what we have so far.
> From their perspective, it is the ordinary state of consciousness which is "disturbed", and the enlightened state of consciousness that is healthy. Who are we to insist otherwise?
We are hackers :p