All swans are white.
If we think this is a falsehood then this depends on how we define the swan. Once, swans were defined as large, white birds with long, S-shaped necks. Their whiteness was a defining feature of the swan, and if the bird wasn’t white then it wasn’t a swan.
Later, fashions for defining swans changed. We became more interested in their musculoskeletal characteristics then their plumage. If we encountered a bird with the S-shaped neck and the musculoskeletal characteristics then we started calling it a swan, even if the bird was black.
In the future, when the genotype of the swan is mapped we might, for reasons of heredity, find ourselves calling a bird a swan, even if it doesn’t have the S-shaped neck and comes in all manner of colours.
So, which is the better, truer definition of the swan? The plumage-based definition, the musculoskeletal definition, or the genetic definition? Or indeed any of the infinite ways in which we might define a swan? Call? Colour of eye or bill? Etc?
This is important to know because unless we know the best way to define a swan our opening statement ‘all swans are white’ is in a terrible logical limbo:
To the plumage-definer the statement is true; to the musculoskeletal-definer it is false.
This means that the statement is both true and false, depending on your perspective of what a swan is. In other words, all swans seem to be both P and not-P.
To resolve this intolerable contradiction it is necessary for us to explain what a swan really is – what is the definition of the true swan? How do you know?
If you can manage this then you may, with justification, go on to resolve the contradiction. If you cannot manage this then we are not logically permitted to step beyond the contradiction:
So, ‘swans are both P and not-P’ becomes the most illogical, and at the same time, logical viewpoint to hold.
I wonder where this leaves logic?
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Aristotle distinguished between essential characteristics and accidental characteristics.
ReplyDeleteAn accidental characteristic does not enter into the definition of a species.
In our case the colour seems to be an accidental characteristic.
Another example: a raven which is an albino is still a raven, isn´t he ?
Yes, the point I'm making in Aristotelian terms is that there is no way of determining what are the essential and what are the accidental characteristics. There is no reason why feather colour could not be essential, in which case an albino 'raven' would not be a raven if the raven is defined as having black feathers.
ReplyDeleteA good example of this is the black panther. This was considered to be a different animal to the leopard in the days when fur colour was an essential characteristic.
Now, after a change in fashion, fur colour is considered an accidental characteristic - thus the black panther is viewed as a mere colour variant of the leopard (Panthera pardus).
Is there really no way of determining what are the essential and what are the accidental characteristics ?
ReplyDeleteI can think of at least one criterium, which our biology teacher offered at school : those who can procreate with each other belong to the same species and therefore the differences between them are only accidental.
If the black panther can procreate with the white panther or the pink panther they belong to the same species and the colour is an accidental characteristic.
A horse can procreate with a donkey, but the mule cannot procreate with anyone, so horse and donkey belong to different species and the diffrences between them are essential.
"Is there really no way of determining what are the essential and what are the accidental characteristics ? "
ReplyDeleteThere are a million different ways of making a distinction between accidental and essential - but the decision itself will always be arbitrary. There is no higher perspective from which we can distinguish what should be essential and what should be accidental.
When we apply logical arguments to the real world, (and this is real the subject of this post), we must 'freeze' the definitions of our concepts for the argument to remain true to its premises. But this act of 'freezing', which is forming the belief that some traits really are essential, is arbitrary, and, therefore quite illogical.
Trying to make some order in a chaos is not a bad thing.
ReplyDeleteOne can improve on the way.
But you seem to dismiss all effort of ordering things just because some minor imperfections.
Chaos and anarchy is not a better option than provisory order which leaves room for improvement.
Logos, the language is a tool on the way to creating order in the chaos.
You seem to say: if swan is not possible to define, because of colour variations. let´s throw away the word "swan".
All other words too then ?