If you were to ask someone to give an example of Buddhist doctrine, the example given may well be ‘the Buddhist doctrine of no-self’.
But actually that isn’t true, in two senses.
Firstly, at no point in the sutras or anywhere else did the Buddha either deny the self or affirm the self.
He just pointed out that our ideas of what the self is are incoherent and contradictory, and whether or not the self existed, we couldn’t find it in any of the familiar places.
And he did this because thinking in terms of self and world is obviously dualistic; but likewise thinking in terms of no self and world is dualistic too.
It is as if one sketched out an outline of a person, filled it up with imaginary karma, and called the whole thing ‘self’. And you then took that content away, simply leaving the outline again, and this time filled up the space with imaginary enlightenment. What is the difference, really?
And this is the second sense. There isn’t ‘Buddhist doctrine’ in the normal sense, because the heart of Buddhism isn’t within the conceptual realm.
If our understanding is theoretical then our liberation will also be theoretical.