René Descartes wrote in 1641, "I think; therefore I am." Descartes realized that we could never be sure that our perceptions are true - Your memories could be invented. Your room could be a hallucination. - But he knew with certainty that he existed. The fact that he could ask questions meant that he existed.
About a hundred years later, David Hume showed that we could never be sure that our understanding of cause and effect is true.No matter how often something occured in the past, it is impossible to prove that it will happen in the future.
Immanuel Kant built on Descartes' and Hume's ideas and said there is a difference between our perception of something and the thing in itself.I can see a tree, I can touch it and experience it, but I can never know the tree or experience life as the tree experiences life. I can only interpret the tree through my own senses.
All this is a way to show that whatever you believe you know to be true - you don't. Human understanding is too limited. We should then be careful what we choose to accept as true.
For your reading pleasure, here are ten schools of philosophy you should know about. Some of them are commonly misunderstood, and we correct that problem here. The leading philosophy among angsty teens who misunderstand Nietzsche.
Nihilism is the philosophical thought process that argues that all aspects of life lack a specific meaningful quality - the belief that life has no meaning. True nihilism rejects the meaning in more than just life, but also in ideologies, value structures, government, or other institutions, rendering all aspects of life meaningless.
Nihilism originated during 300 B.C.E. where certain discussions by the Buddha related to our actions having no meaning or consequences in this world.
The Greek statesman Demosthenes also contributed to its origins.
The modern understanding of nihilism is associated with Friedrich Nietzsche, who said all aspects of life are subjective, not objective, also adding that this belief will lead to the destruction of all value structures.