When someone says X is Y “by definition,” the fundamental mistake they are making is thinking that the definition decides what belongs in a particular concept. No, the similarity between the objects relative to those around them (as recognized by our brain) is what decides.
The definition is just a reminder, a mental tool to help us keep the sets separate and organized within the context of our knowledge. Due to this, the definition can change as our knowledge grows, and we have the need to make finer separations. But the set doesn’t change.
(Definitions also serve a role in human communication.)
When someone says X is Y “by definition,” the fundamental mistake they are making is thinking that the definition decides what belongs in a particular concept. No, the similarity between the objects relative to those around them (as recognized by our brain) is what decides.
The definition is just a reminder, a mental tool to help us keep the sets separate and organized within the context of our knowledge. Due to this, the definition can change as our knowledge grows, and we have the need to make finer separations. But the set doesn’t change.
(Definitions also serve a role in human communication.)