It's always good to consider the platypus.
A platypus seems like a curious creature. It's ostensibly a mammal but has a bill. It has a poisonous fingernail. It lays eggs. Like a duck it picks up gravel and uses that as teeth. It can sense electric fields and uses them to hunt prey.
But the curiosity of the platypus says more about us than about it. As observers we come to the platypus with a long history of prejudice. We have a formal categorization scheme that affects how we see. A categorization system built out of millennia of observation about the world. Up until the platypus we'd never considered that a single creature could embody such diverse traits. Our system is "mammals", "reptiles", "birds", "amphibians", "fish". This stems from Aristotle who said that life was classified into vertebrates, including viviparous quadrupeds (mammals), birds, oviparous quadrupeds (reptiles and amphibians), fishes, and whales. And then separately cephalopods (such as the octopus); crustaceans; insects, shelled animals and "zoophytes," or "plant-animals".
In the 1970's people like George Lakoff and Eleanor Rosch looked at how our prejudices were informed by our categorization systems. Topics like semantic categorization, mental representation of concepts and linguistics had some impact on our cognition, how we framed concepts. How we think and store memories. That isn't to say we can't think outside the boundaries of our categorization schemes, but it is harder.
When we find ourselves attempting to categorize a system - such as to build a computer model of that system - it is so important to remember that our categorization schemes are not the reality. That in any new territory we will eventually discover the platypus. Any abstraction only maps to what is known.
If we don't leave room for the new then sometimes our software programs cannot even "see" the platypus, or whatever the new is. It can't see transgendered people, it can't see streets that might be only for walking, it can't see the subtle web of relationships between people in a neighborhood. And in that ignorance it renders everything down to what it knows, making the new impossible. The solution to coming across a platypus isn't to kill the platypus but to change how we see it.
