RobbBB comments on Request for Steelman: Non-correspondence concepts of truth - Less Wrong

13 Post author: PeerGynt 24 March 2015 03:11AM

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Comment author: RobbBB 25 March 2015 07:09:58AM 2 points [-]

Can you be more specific? Is '2+2=4' true in virtue of literal mathematical objects like '2' and '4'? If so, how do those objects causally relate to my assertion that 2 and 2 makes 4, or to the evidence underlying that assertion?

Comment author: seer 26 March 2015 03:44:51AM 6 points [-]

If so, how do those objects causally relate to my assertion that 2 and 2 makes 4,

Because they cause there to four apples in a box if you put two apples in, and then put two more apples in.

If both you and a sentient alien in another galaxy write out addition tables, the two tables will be highly correlated with each other (in fact they'll correspond). Which means that either one caused the other, or both have a common cause. What's the common cause, the laws of mathematics.

Comment author: TheAncientGeek 27 March 2015 09:16:43AM 0 points [-]

So maths is physics.

But I can write an equation for an inverse cube law of gravity, which doesn't apply to this universe. What does it correspond to?

Comment author: seer 28 March 2015 02:50:36AM 6 points [-]

So maths is physics.

Not quite, although I agree the approach I describe also applies to establish that the laws of physics exist.

But I can write an equation for an inverse cube law of gravity, which doesn't apply to this universe.

Yes, and if you and the alien both write down a cube law and predict what orbits would be like in a universe where it were true, you would reach the same conclusions.

Comment author: TheAncientGeek 28 March 2015 11:09:34AM 0 points [-]

That doesn't establish that mathematics is true by correspondence,.

Comment author: seer 28 March 2015 07:04:33PM 6 points [-]

So what would you describe as the cause of the correlation in the orbits calculated by myself and the alien?

Comment author: TheAncientGeek 29 March 2015 09:05:01AM 0 points [-]

Running off the same axioms and references rules).

In a sense that means the same laws, but the laws are not independently existing entities that mathematical truths correspond to.

Comment author: seer 29 March 2015 05:50:44PM 6 points [-]

In the Philip K. Dick sense they are.

Comment author: TheAncientGeek 30 March 2015 09:05:59AM 0 points [-]

In the PKD sense, they are not, because finitists and constructivists adopt different axioms able get different results,

Comment author: dxu 28 March 2015 04:37:18AM *  0 points [-]

But I can write an equation for an inverse cube law of gravity, which doesn't apply to this universe.

No, you can write out an equation using suggestively named variables like "G" and "m" and "r". The second the equation stops modeling the strength of the gravitational force, however, it ceases to be a "law of gravity", regardless of what letters you used for the variables. It's just some random equation.

Comment author: TheAncientGeek 28 March 2015 11:03:09AM 0 points [-]

That amounts to saying that what isnt physically true isnt physically true . The point, however, is that what is not physically true can be mathematically true, so mathematical truth cannot consist of correspondence to the physical world,