“Solipsism (i/ˈsɒlɨpsɪzəm/; from Latin solus, meaning "alone", and ipse, meaning "self")[1] is the philosophical idea that only one's own mind is sure to exist. As an epistemological position, solipsism holds that knowledge of anything outside one's own mind is unsure; the external world and other minds cannot be known, and might not exist outside the mind. As a metaphysical position, solipsism goes further to the conclusion that the world and other minds do not exist” Wikipedia

Solipsism is a theory of Philosophy that believes nothing outside the mind exists, and if it does, we can never know it. Gorgias of Leontini who is said to be the theorist of solipsism poses these questions:

1. Nothing exists
2. Even if something exists, nothing can be known about it
3. Even if something can be known about it, knowledge about it can't be communicated to others
4. Even if it can be communicated, it cannot be understood

Since we all have our own memories and views of the world, no two are the same. So
Leontini argues that no-one can ever know reality. He claims that nothing exists outside
of our individual consciousness.

We can only ever know what we know and no-one else can know the same as us. Of
course we can have knowledge of something the same, however the method, associations and meaning are individual.

Can you remember having dreams that seemed so real that you felt like they really
happened? In some cases people can find it difficult to differentiate between what really happened in their life, and what was a dream.

A Course In Miracles believes that life is all a dream and we are the dreamer of it. It goes on to say that when we become aware of our true nature, we have no need of the dream anymore and awaken to “reality”.

Theories about us living in a holographic universe are based on the premise that everything we see is a projection from our mind. Theorists claim that nothing in the universe is real, everything when magnified down small enough is just empty space, and more like a thought than anything solid.

We can only take in so much information at any time and depending on our processes, beliefs and the relevance of information available, the mind deletes what it thinks is unnecessary. Information that is unnecessary to one, may be very necessary to another. How is it possible to know anything fully?

Many find solipsism stupid since we can all validate that we are here and the things we see are real. However we are always validating ourselves through means that are unreliable and depend on another person to agree with us.