question
Can we distinguish between dream and reality? What defines reality?
evidence
When we are dreaming, we can’t tell that we are dreaming. Hence, how can we know that reality is “real”?
All composed things are like a dream,
a phantom, a drop of dew, a flash of lightning.
That is how to meditate on them,
that is how to observe them. — The Diamond Sutra
conclusion
- Reality cannot be clearly distinguished from dreams through sensory perceptions alone
Wikipedia excerpt
The dream argument came to feature prominently in Mahayana and Tibetan Buddhist philosophy. Some schools of thought (e.g., Dzogchen) consider perceived reality to be literally unreal. As Chögyal Namkhai Norbu puts it: “In a real sense, all the visions that we see in our lifetime are like a big dream … .”
The dream argument is the postulation that the act of dreaming provides preliminary evidence that the senses we trust to distinguish reality from illusion should not be fully trusted, and therefore, any state that is dependent on our senses should at the very least be carefully examined and rigorously tested to determine whether it is in fact reality.