The first of Descartes’ meditations posit an argument which suggests no objective way to confirm whether we are awake, or actually dreaming. However, Descartes’ did not actually think the world could be a dream; his dreaming argument was ‘designed’ to break the readers’ belief/acceptance of sensory experience, at least casting doubt on its capacity to provide ‘truth’.
Descartes’ was embarking on a sceptical project to clear away the rubble of what he thought were false ideas. This project was essentially against all metaphysics of his day, which was generally Aristotelian. To begin his destruction of sense experience as a giver of truth, he needs to cast doubt on them.
His dreaming argument does this; he begins by noticing how strong and vivid his experience is. Sitting by the fire, warm from the heat, writing by the glow of the fire. Then he begins to doubt, claiming that he has often had dreams which were so vivid that he has thought he was sitting by the fire, when in fact he was asleep in bed. He aims to show that we have no sure way of knowing the difference between dreaming and reality. Our senses do not always give us correct information about the world.
Part of this project was to prepare the reader meditating with him for his theories of mind and ideas. With this dreaming argument, along with his ‘evil demon’ argument which follows (to cast doubt on mathematical knowledge), he aims to lead the reader down a path of acceptance in innate ideas, particularly of an incorporeal self, and of god.
After inducing this doubt, and proving the existence of a soul, and god, Descartes will return the use of sensory experience in defined limits. So Descartes certainly does not wish to suggest that the world could be a dream; he simply wants to induce doubt on the senses, and prepare the reader for his ‘new’ theory of mind, and the necessity of a god.