As described earlier, there are many different schools of Buddhism, which provide different presentations of the Buddha's teaching. Different schools appeal to different personalities, and no one school claims to be 'right'.
So what is it that all forms of Buddhism have in common, and what differentiates Buddhism from other religions and philosophies?
The defining features of Buddhism are THE FOUR SEALS OF THE DHARMA - four statements about the world which form the basis of all Buddhist teachings. The four seals aren't 'revealed truths' which we have to take on trust from some self-proclaimed 'prophet' who claims to have heard the voice of God, they are philosophical statements derived from logic and experience.
(1) LACK OF INHERENT EXISTENCE
All functioning phenomena and persons are composite and ultimately 'empty' or ‘unfindable’ upon analysis. They lack 'inherent existence' and their existence in fact depends upon three factors external to themselves:
(ii) structural relationships with other phenomena, and
(iii) mental labelling
Since functioning phenomena are composite, and exist dependently upon changing causes and changeable structural relationships, they are necessarily impermanent.
All functioning phenomena are subject to change, growth, dissolution and decay. Even the sun, planets and galaxies are changing and will one day cease to exist.
An entity that was not composite, or capable of becoming composite, could not function. Things can only interact with one another by giving and receiving parts of themselves as matter/energy. A non-composite entity could never undergo any internal rearrangements or changes of state. It would remain in eternal, undetectable isolation.
In fact, to say that something 'exists' is an arbitrary statement. All we are saying is that its rate of disintegration is negligible on the timescale of our lifetime. In reality, all functioning phenomena are impermanent - it's just that some are more impermanent than others.
All 'things' are impermanent, and so all things are in reality processes. Things do not stay the same from one millisecond to the next. Anything composed of atoms is composed of parts in a constant state of flux. 'Existence' is merely impermanence viewed in slow-motion.
(3) UNSATISFACTORINESS (DUKKHA)
All emotions based on the three mental poisons of attachment, aversion and ignorance are ultimately painful. You can never have enough worldly possessions, and even if you did you'd worry about losing them since they are all impermanent. And you've got to lose the lot eventually when you shuffle off your coil, because you yourself are impermanent.
All materialistic cravings eventually lead to disappointment and worse. This is known as dukkha. The root cause of dukkha is grasping for inherent existence. The mind regards phenomena and persons as being permanently and inherently pleasant or unpleasant, and develops aversion and attachment towards the things or persons ‘in themselves’. All emotions which are contaminated by aversion and attachment are ultimately aspects of suffering.
(4) THE TRUE NATURE OF THE MIND IS PEACE A mind that has fully realised the lack of inherent existence of all phenomena will be totally free from suffering. The sky-like clarity of the mind is obscured by the thunder clouds of anger, attachment and ignorance. The true nature of the mind is Nirvana - which is NOT nothingness, but the non-conceptual peace 'which passeth all understanding'.
Diagnosis and Treatment
If we regard the Buddha as a doctor, then the Four Seals are his diagnosis of our deluded state of mind, and the treatment he prescribes is Dharma Practice.
- Sean Robsville
Buddhism versus Materialism
Dukkha, Dawkins, Darwinism and the Selfish Gene
Buddhism, Rationalism and Empiricism - The Kalama Challenge
Consciousness and mind are not emergent phenomena
Essentialism in Physics, Chemistry and Biology
Existence, Impermanence and Emptiness in Buddhism
Inherent Existence in Buddhist Philosophy
Sunyata - the emptiness of all things