This is not a sentence
Does "a practice not unlike the ‘artful trick’ of declaring: ‘This is not a sentence’" mean a way of self-denial as easy as saying that this sentence that you are reading is not actually a sentence? Does "artful trick" have an ironic sense?

Context:

So, whilst situationism veiled itself in ambiguity, resisting a systematic categorisation of any kind to the point of denying its existence altogether – a practice not unlike the ‘artful trick’ of declaring: ‘This is not a sentence’ – there is a distinct situationist impulse that persists and is of particular use to anyone weighing the increasingly significant relationship of art and the city

Question

This is not a sentence
Does "a practice not unlike the ‘artful trick’ of declaring: ‘This is not a sentence’" mean a way of self-denial as easy as saying that this sentence that you are reading is not actually a sentence?  Does "artful trick" have an ironic sense?

Context:

So, whilst situationism veiled itself in ambiguity, resisting a systematic categorisation of any kind to the point of denying its existence altogether – a practice not unlike the ‘artful trick’ of declaring: ‘This is not a sentence’ – there is a distinct situationist impulse that persists and is of particular use to anyone weighing the increasingly significant relationship of art and the city

Answer

The artful trick here refers to the deliberate self-referential paradox represented by the famous proposition "This is not a sentence", or perhaps more generally, something that can be considered in two ways, each contradicting the other. In the case of "This is not a sentence", it clearly *is* a sentence according to its structure, but it is *not* a sentence according to its meaning.  There are other examples of this - including perhaps the "practice" being refered to in the text, and yes these might well be considered artful or prevocative tricks, intended to challenge and confuse.