Maybe you should try to be a little less condescending. It is not very becoming nor a good way to represent this community.

Yes, phenomenologically if I think of the Spaghetti Monster, it exists as an object in a different way as the book that I am looking at. Just as the book I am currently looking at exists in a different way than than this other book that I am remembering. Do you deny that the things in my memories exists as objects of my thought? Like I said in my post, thought is composed of Act -> Content -> Object... Always. You cannot have an Act without a Content, nor a Content without and Act, nor a Content without an Object.

In phenomenology we speak of conscious relationships with objects, different objects have different types of relationships, or in phenomenological jargon, different ways of intending.

Phenomenologically, that unicorn you speak of exists as an object of your conscious thought and is thereby known to you. It's known and exists in a different way than, say, this book next to me, but it does exists.

If all conscious thought is composed of an Act, a Content, and an Identical Object in a relationship, then the conscious relationship You have with said unicorn is also composed of an Act, Content, and Identical Object. It seems to me that the content is known to you, an thus the unicorn's existence is known to you.

Question should be :

Can we know that something exist but actuality it doesn't exist?

Answer: you and 6 billion humans with beliefs(do not exist).

When beliefs do not exist then anything you manifest do not exist as well. Hue-man thinks hue-man exist , but he does not know he does not exist.

If we know there are no unicorns, then we know there are no unicorns in some different galaxy.

All knowledge is also belief. We cannot know something unless we also believe it. But knowledge is not only a matter of belief, it is a matter of true belief, and it is a matter of justified belief. Why wouldn't you think that we have true justified belief that there are no unicorns?

Let me add that although I know there are no unicorns, it might turn out that I only believed I know there are no unicorns, but I was wrong. Of course, that goes without saying, since I am a fallible human being.

Hi, Ken. It seems to me that the sentence, "knowledge is not only a matter of belief, it is a matter of true belief, and it is a matter of justified belief," drastically conflicts with your sentence, "although I know there are no unicorns, it might turn out that I only believed I know there are no unicorns." According to the first sentence, it is impossible for you to be wrong if you know there are no unicorns.

Aristotle wrote that you cannot have a science (knowledge) of non-being.

Can we ever be positively (not absolutely) certain that any particular thing doesn't exist?

we know that in the Universe absolute nothing does not exist

In order for everything to be possible, the world would have to be in dynamic flux because in order for everything to be possible, no stable identities would be tolerable.

Well, the point I made was that no two copies of the exact same thing can exist, and similarly (because of the role of structure as previously described), it's impossible for a concept to be the exact same thing as an object. Therefore, nothing we imagine actually exists, but rather only approximations thereof.

Regarding your statement, I'm not quite saying that nothing is possible, but instead, that no pure identities can be isolated. This is because, one, everything is always changing, and two, structure has a role in observation nevermind interaction and how observation always has the potential to be a form of interaction. For example, the double slit experiment and it's counterpart, the delayed choice experiment. As such, everything is possible, but what's impossible is the ability to identify an exact replication of what's imagined.

Yes, I think we're largely talking about different things. The actual is not possible - it is actual. The possible is not actual - it is possible. Perhaps "potential" would bring out the meaning more. Your post encouraged me to think along these lines.

To me nothing cannot not exist, as if you think of it, then it MUST exist because of the existence of the thought creates the existence of it inside of your mind, prima facie everything exists that you can think of.

To view this topic from a bit different view..

Isn't this excatly why most philosophy/philosophers in general are so little used in buisness, politics ..etc, because they endulge themselfs in utterly useless topics?

Amateur online "philosophers" often do such things, and the bad ones among the famous tend to be useless.

However, your test is not a good one. Most businesses do not use theoretical physicists or those in very advanced realms of mathematics, either, so something not being used much in business does not mean that something has no value. And often these things give birth to other ideas later on that do show up in businesses at a later time. When Leucippus theorized that the world is made up of atoms, it was a useless idea. But it has proved extremely useful much later on.

To view this topic from a bit different view..

Isn't this excatly why most philosophy/philosophers in general are so little used in buisness, politics ..etc, because they endulge themselfs in utterly useless topics?