Rolfe
Adult human female
This is simplistic, but here goes. Imagine an orchard with just two types of tree - or just two trees, if you like. Apple and pear. It's autumn, and harvest time. The orchard is stripped of all fruit, from both types of tree. How do you go about separating the apples from the pears?
Most of the time this will be perfectly simple. We all know what an apple looks like, and a pear. Get on with it. But there will be some fruit that are difficult to categorise due to miss-shapes or pest damage or whatever. Most of those can probably be categorised on closer inspection too, but there may still remain some doubful ones. It would be possible to go as deep into this as you had to, to decide whether any individual fruit was an apple or a pear. Microscopic examination, DNA sequencing, whatever. Because each one is in fact either an apple or a pear. No matter how mis-shapen or discoloured. Each fruit grew on one of the two trees. Not both, and not neither. There is no such thing as a pepple.
There will be spectra of all sorts of characteristics, such as weight and colour and peel thickness and length/circumference ratio. But the reality of whether each fruit is an apple or a pear is binary. One or the other, not both, not neither, and none of them are oranges either.
Most of the time this will be perfectly simple. We all know what an apple looks like, and a pear. Get on with it. But there will be some fruit that are difficult to categorise due to miss-shapes or pest damage or whatever. Most of those can probably be categorised on closer inspection too, but there may still remain some doubful ones. It would be possible to go as deep into this as you had to, to decide whether any individual fruit was an apple or a pear. Microscopic examination, DNA sequencing, whatever. Because each one is in fact either an apple or a pear. No matter how mis-shapen or discoloured. Each fruit grew on one of the two trees. Not both, and not neither. There is no such thing as a pepple.
There will be spectra of all sorts of characteristics, such as weight and colour and peel thickness and length/circumference ratio. But the reality of whether each fruit is an apple or a pear is binary. One or the other, not both, not neither, and none of them are oranges either.