Final answer:
Daoist philosophy posits that speaking about the 'dao' can limit its understanding, as the dao transcends verbal expression and is understood through living spontaneously in harmony with its inherent contradictions.
Step-by-step explanation:
The question at hand explores the concept of speaking about 'non-being' as understood in Daoist philosophy. Daoism suggests that the dao is beyond the scope of language and that speaking about it can diminish its essence. The philosophical texts emphasize that true knowledge of the dao comes from a non-verbal understanding and living in harmony with its contradictory nature. Thus, 'speaking what is not' hints at the complications language introduces when discussing abstract concepts like the dao, which are not fully comprehensible within the confines of rational speech.
This is exemplified by the Daoist principle that 'Those who know do not speak; those who speak do not know.' It points to an understanding of reality and morality that is not fixed or easily expressed in words but is better aligned with living in accordance with the spontaneous and flow-like nature of the dao. The performativity of language and the limitations of speech in capturing the breadth of metaphysical realities are important aspects of this philosophical perspective.