Life as we know it may simply be an illusion of the mind, a simulated reality. This means that any achievements we make are ultimately meaningless as it is uncertain whether they really happened or matter, and any experiences we have are no more meaningful than dreams or hallucinations. Many skeptic philosophers have given reasons to doubt our existence. Zhuangzi famously spoke of 'The Butterfly Dream': "I dreamt I was a butterfly ... conscious only of my happiness as a butterfly, unaware that I was myself. Soon I awoke, and there I was ... myself again. Now I do not know whether I was then a man dreaming I was a butterfly, or whether I am now a butterfly, dreaming I am a man." Here, Zhuangzi says that if his dream of being a butterfly felt as real as being awake, then the waking world could be as false as a dream. Other skeptical scenarios, such as Bertrand Russell's 'five minute hypothesis' (see proponents), Descartes' 'evil demon problem' in which one may be deliberately misled to believe everything which is false, and the 'brain in a vat' scenario wherein 'reality' is being simulated by a mad scientist, build upon this statement: it is impossible to know whether this life is real, so it is impossible to find true purpose.
Some things, like feelings and thoughts, are definitely real. Descartes famously said, "I think therefore I am", meaning that doubting our own existence proves that we are real - something which does not exist would not be able to doubt or think. Therefore, we cannot conclude that life is purposeless purely for lack of certainty of our own existence, as even thinking proves our own existence. In philosophy, Occam's razor can be used to negate this argument. This is the idea that the argument which requires the least assumptions is most likely the correct one. Believing that everything around us is an illusion requires more assumptions than it does to just assume that this is all real - believing none of this is real requires the disregard of every sensation, thought, and experience we have ever had. Therefore, it is the best and most sane option to live as though our waking life is real, meaning that any of the purposes of life, whether that be happiness, survival, or doing good, can be considered real and valid.
Rejecting the premises