Dzongsar Jamyang Khyentse Rinpoche, author of What Makes You Not a Buddhist provides four criteria to consider. To be a Buddhist, one must believe in all four of these tenets or seals. These are: 1) all compounded things are impermanent, 2) all emotions are pain, 3) all things have no inherent existence, and 4) nirvana is beyond all concepts.
Let's continue with number three: "All things have no inherent existence." What could this possibly mean? Things certainly feel real, don't they? Isn't this just some kind of Buddhist double-talk? Physics may provide a clue. The objects we interact with every moment of our lives, including the bodies we have are mostly made of space. Each atom is mostly space. The appearance of solidity is provided by the energy of the circulating electrons and other particles of each atom. At the quantum, sub-atomic, level things get really weird and unpredictable, yet the world of objects we inhabit follows the laws of physics. Richard Dawkins calls the world we inhabit "middle world." Middle world, however, is not the absolute nature of things but only its relative nature. A physicist at the University of Buffalo once told me that if all the space was taken out of atoms the universe would be the size of a bowling ball. The entire universe! Perhaps this is what the Buddha meant by "all things have no inherent existence" even though he did not have the scientific knowledge to prove it. What are the implications of this lack of inherent existence? For one, I think it means we should not take ourselves or our situations so seriously. The universe is simply made of space! It's all empty. Another implication is this emptiness that I just mentioned. What is emptiness? Beyond the layers and textures of desire lies bare existence. This emptiness is considered to be luminous but lacking any solidity. The implication stemming from the Buddha's teachings is thus generosity. Generosity? When we no longer cling to things as me and mine, we are free to be more generous. When we no longer put vast amounts of energy into protecting things with no inherent existence we are lighter (that is, less self-important as noted above), and more generous. To read further:
To learn more about Dongsar Khyentse Rinpoche, please visit his website Siddhartha's Intent.