On black swans - that old canard!
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?
(Nikolai)
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?
(Nikolai)