“All models are wrong, some are useful.”
This aphorism is generally attributed to the statisticianGeorge E. P. Box but is one I believe applies to all aspects of life, far beyond statistics.
For me, it is ultimately talking about ontology, what things exist and how to categorise them. All categories are wrong; they all break with enough testing. It is impossible to come up with a description of a chair that includes all chairs and excludes everything that is not a chair. The category of chair is useful in many scenarios, but we should understand its limitations and recognise when chair/not chair isn't a useful model of the world for the question we are trying to answer.