Solipsism is the philosophical attitude according to which the thinking subject cannot affirm that his own individual existence insofar as every other reality is resolved in his thought. Radical solipsism preaches that everything I can know about the world is inside my head. For the subject, all that he can know about an external object is the sensation that this object gives him and the mental image that derives from it: from the sensations ideas will be generated and from the ideas images will be produced.
According to Descartes we cannot know with certainty, if we rely only on the senses, that external reality really exists.
So the idea of solipsism is that we cannot prove that external things exist and that consequently the only reality we can claim to know is that of our ideas.
According to J. Locke, however, if our sensations are passive, that is, we receive them from the outside and therefore we are not creating them with our mind, it means that necessarily there must be something outside that is giving me those sensations.
The concordance between subjects who see the same object, albeit with slight differences, could prove the existence of external matter.
There are elements of quantum physics that we cannot see due to Heisenberg's uncertainty principle:
if I were the inventor of everything I perceive, it would be difficult to explain the unpredictability of observing quantum physics.
This would be enough to undermine solipsism, even if on a philosophical level it would continue to be very difficult to prove that the external world exists.
Having the eyes of the philosopher, therefore, means seeing things outside the prejudices that society imposes on us, to see how much complicated beauty there is under the alleged simplicity of this world.
As expressed by a good part of Eastern mysticism, the truth can only reside within us and never outside.
Solipsism, in its most positive sense, gives us new eyes, those of the solitary being, useful for looking for the hidden (often lost) treasures within us.
