@John K
Would Anomalous's claim that maths is subjective indicate sympathies with an intuitionistic conception of math?
What do you make of intuitionism?
Intuitionism as far as I understand it says that maths is a human construct that has no existence in the world other than as this. So bye-bye all those Platonic and Pythagorean idealisations. It’s not something I’ve thought very deeply about but it’s an intriguing issue. Maths would then be subjective in the same way as any other symbolic representation of meaning is within
@Anomalous 's thinking.
Given my previous comments in this thread let’s make it clear that in this one I'm taking it that the external, objective world exists and our minds have got access to it through our senses and the inferences we build on them, but we experience it consciously only through a model that our minds create of it in approximate real-time.
It seems to me that there is nothing conclusive that can be said, but there are indications that support the idea maths is representative of something that exists outside human minds. The evidence is:
- It can be used to predict the behaviour of many things in the external world with amazing accuracy.
- It does this consistently for anyone who has grasped the rules and applied them to the right data in the right way.
- It throws up surprises that show that some maths applicable in one physical context turns out to be applicable in completely different ones too.
- etc
I think that it is parallelling something about the intrinsics of certain aspects of reality with very great precision. That's not to say necessarily that we are discovering maths but it certainly feels like we are inventing a simulation language that has the potential to mirror those aspects of reality with arbitrarily close precision. How close depends on things that lie outside the realm of maths - the discoveries of science and our ability to express tham well in mathematical terms. That spills over into questions about how real are the laws of physics, etc.
Now on the other hand, pure mathematics is simply a game of logic looking inwards on itself. I think it may be arguable that because it is a logically closed system with constructed axioms and rules then there is a sort of artificial objectivity about that sort of maths, regardless of whether applied maths is completely subjective or not. Because there always has to be an axiomatic starting point though, it could be argued that these are of necessity expressed in language that itself is subjective.
My gut feeling is that in maths we are dealing with something that is a human construct but which is eerily echoing the way reality behaves. But maybe that's true of all our mental relationshipo with the world?
From the brief glance I've had at intuitionist maths, there are some intriguing aspects that I haven't yet connected to the main premise of subjectivity. The most in-you-face is it's replacement of classical mathematical logic with an alternative set of rules. The idea that ~~A = A is fundamental to traditional maths, but this is denied in intuitionism - in the sense that it isn't necessarily true. That means you cannot prove something is true by falsifying it's opposite, but have to use constructive methods instead. I don't really know much about the history of this, but it probably comes from the melt-down in set theory in the late 19th century, together with the problems of dealing with Cantor's 'sets' of different sorts of infinity.