All conditioned phenomena are characterised by impermanence, unsatisfactoriness, and non-self.
Anicca, impermanence
All conditioned things are impermanent, subject to change, alterable - and therefore unreliable as a source of sustainable happiness.
Dukkha, unsatisfactoriness
All conditioned things are unsatisfactory, and therefore pursuing them and expecting satisfaction is deluded and unreliable.
Anattā, non-self
All conditioned things are not-self, including the thing we think is our self.
In his chapter on ‘the doctrine of no-soul’ (anatta), Rahula refutes a variety of scholastic attempts to argue that Buddha did not deny the existence of a capital-S Self or soul, even though he may have denied the reality of the relative or mundane self, small-s self. These arguments might[^5] be a good starting point for anyone questioning the Buddha’s claim about the non-existence of a permanent or absolute ‘true self’. They also might not - I found them a bit murky.
A good starting point for me is recognising I may need to unpack how my faith is impacted by considerations of whether there is more to the self than Buddha understood. Maybe modern science or neuroscience has discovered or made a convincing case that there is an essential soul or aspect of our being that is unchanging> So I checked, and actually neuroscience has confirmed Buddha’s insight more than challenged it, supporting the understanding that the self is a process not a thing. [citations]
Still there is the concern of whether practising dhamma works at the level of personality, and if not, which modalities do I need to complement the practice? What sort of psychological technology might amount to a complementary medicine to the Buddha’s dhamma? I am exploring this more in 01. The Nature of Doubt, in the section about whether Buddhism is sufficiently holistic.