Mar 11, 2022 07:23 PM
https://aeon.co/essays/natural-laws-cant...be-defined
INTRO (Marc Lange): In our science classes, we all learned some examples of what scientists currently believe (or once believed) to be laws of nature. Some of these putative laws are named after famous scientists (such as Robert Boyle and Isaac Newton). Some are generally called ‘laws’ (such as the laws of motion and gravity), while others are typically called ‘principles’ (such as Archimedes’ principle and Bernoulli’s principle), ‘rules’ (such as Born’s rule and Hund’s rule), ‘axioms’ (such as the axioms of quantum mechanics), or ‘equations’ (such as Maxwell’s equations).
Laws of nature differ from one another in many respects. Some laws concern the general structure of spacetime, while others concern some specific inhabitant of spacetime (such as the law that gold doesn’t rust). Some laws relate causes to their effects (as Coulomb’s law relates electric charges to the electric forces they cause). But other laws (such as the law of energy conservation or the spacetime symmetry principles) do not specify the effects of any particular sort of cause. Some laws involve probabilities (such as the law specifying the half-life of some radioactive isotope). And some laws are currently undiscovered – though I can’t give you an example of one of those! (By ‘laws of nature’, I will mean the genuine laws of nature that science aims to discover, not whatever scientists currently believe to be laws of nature.)
What all of the various laws have in common, despite their diversity, is that it is necessary that everything obey them. It is impossible for them to be broken. An object must obey the laws of nature. In this respect, a law of nature differs from the fact that all gold cubes are smaller than a cubic mile, the fact that all the apples currently hanging on my apple tree are ripe, and other so-called ‘accidents’. Although this fact about gold cubes is as universal, general and exceptionless as any law, it is not necessary. It could have been false. It is not inevitable or unavoidable that all gold cubes are smaller than a cubic mile. It just turns out that way.
But although all these truisms about the laws of nature sound plausible and familiar, they are also imprecise and metaphorical. The natural laws obviously do not ‘govern’ the Universe in the way that the rules of chess govern a game of chess. Chess players know the rules and so deliberately conform to them, whereas inanimate objects do not know the laws of nature and have no intentions.
For 4 to be a prime number would require more than merely a violation of the laws of nature
Furthermore, there are lots of things that we would describe appropriately (in a given conversational context) as ‘impossible’ but that do not violate the laws of nature. It is impossible for me to wish you ‘Good morning’ in Finnish because I do not speak Finnish, to borrow an example from the philosopher David Lewis (1941-2001). But my doing so would not violate a law of nature: I could learn Finnish. My car cannot accelerate from 0 to 60 mph in less than 5 seconds, but that impossibility is not the same as the kind of impossibility involved in my car accelerating from 0 to beyond the speed of light. Now we are using the laws of nature to help us understand the kind of impossibility that is supposed to distinguish the laws of nature. We have gone around in a tight circle rather than put our finger on what makes a fact qualify as a law rather than an accident.
Moreover, although accidents lack the kind of necessity that laws of nature possess, there are other facts that possess the kind of necessity that laws possess but are not laws – or, more accurately, they are not merely laws. While accidents are too weak to be laws because it would have been too easy to make them false, certain other facts are too strong to be merely laws because they are harder to break than even the laws themselves. For instance, the fact that all objects either contain some gold or do not contain any gold is a fact that has even more necessity than a law of nature does. It is still a fact even in the Star Trek universe, where the laws of nature are different (since starships routinely accelerate beyond the speed of light). For 4 to be a prime number is likewise impossible even in the Star Trek universe. It would require more than merely a violation of the laws of nature.
The laws of nature, then, fall somewhere between the accidental facts (which lack the laws’ necessity) and the facts that possess a stronger variety of necessity than the laws do. The laws are distinguished by having the variety of necessity that distinguishes the laws. But we must do better than that if we are to understand what a law of nature is.
Philosophers do not aim to discover the laws of nature. That’s a job for scientists. What philosophers aim to do is to figure out what sort of thing scientists are discovering when they discover the laws of nature. The philosopher’s aim is not to help scientists do their job. Instead, the philosopher’s aim is to better understand the job that scientists are doing. For instance, when scientists explain why something happens by appealing to a law of nature that they have discovered, what makes a law able to answer such a ‘Why?’ question? To understand scientific understanding is a job for the philosophy of science.
Of course, it can be difficult to reach this philosophical understanding, and I will ask you to bear with me as I guide you – step by step – towards understanding what a law of nature is. I hope that as a useful byproduct, you will also enjoy seeing how a philosopher utilises a few bits of logic (paging Mr Spock!) to grapple with the question ‘What is a law of nature?’ Hold on: I hope you will find the final result to be elegant and illuminating... (MORE - details)
INTRO (Marc Lange): In our science classes, we all learned some examples of what scientists currently believe (or once believed) to be laws of nature. Some of these putative laws are named after famous scientists (such as Robert Boyle and Isaac Newton). Some are generally called ‘laws’ (such as the laws of motion and gravity), while others are typically called ‘principles’ (such as Archimedes’ principle and Bernoulli’s principle), ‘rules’ (such as Born’s rule and Hund’s rule), ‘axioms’ (such as the axioms of quantum mechanics), or ‘equations’ (such as Maxwell’s equations).
Laws of nature differ from one another in many respects. Some laws concern the general structure of spacetime, while others concern some specific inhabitant of spacetime (such as the law that gold doesn’t rust). Some laws relate causes to their effects (as Coulomb’s law relates electric charges to the electric forces they cause). But other laws (such as the law of energy conservation or the spacetime symmetry principles) do not specify the effects of any particular sort of cause. Some laws involve probabilities (such as the law specifying the half-life of some radioactive isotope). And some laws are currently undiscovered – though I can’t give you an example of one of those! (By ‘laws of nature’, I will mean the genuine laws of nature that science aims to discover, not whatever scientists currently believe to be laws of nature.)
What all of the various laws have in common, despite their diversity, is that it is necessary that everything obey them. It is impossible for them to be broken. An object must obey the laws of nature. In this respect, a law of nature differs from the fact that all gold cubes are smaller than a cubic mile, the fact that all the apples currently hanging on my apple tree are ripe, and other so-called ‘accidents’. Although this fact about gold cubes is as universal, general and exceptionless as any law, it is not necessary. It could have been false. It is not inevitable or unavoidable that all gold cubes are smaller than a cubic mile. It just turns out that way.
But although all these truisms about the laws of nature sound plausible and familiar, they are also imprecise and metaphorical. The natural laws obviously do not ‘govern’ the Universe in the way that the rules of chess govern a game of chess. Chess players know the rules and so deliberately conform to them, whereas inanimate objects do not know the laws of nature and have no intentions.
For 4 to be a prime number would require more than merely a violation of the laws of nature
Furthermore, there are lots of things that we would describe appropriately (in a given conversational context) as ‘impossible’ but that do not violate the laws of nature. It is impossible for me to wish you ‘Good morning’ in Finnish because I do not speak Finnish, to borrow an example from the philosopher David Lewis (1941-2001). But my doing so would not violate a law of nature: I could learn Finnish. My car cannot accelerate from 0 to 60 mph in less than 5 seconds, but that impossibility is not the same as the kind of impossibility involved in my car accelerating from 0 to beyond the speed of light. Now we are using the laws of nature to help us understand the kind of impossibility that is supposed to distinguish the laws of nature. We have gone around in a tight circle rather than put our finger on what makes a fact qualify as a law rather than an accident.
Moreover, although accidents lack the kind of necessity that laws of nature possess, there are other facts that possess the kind of necessity that laws possess but are not laws – or, more accurately, they are not merely laws. While accidents are too weak to be laws because it would have been too easy to make them false, certain other facts are too strong to be merely laws because they are harder to break than even the laws themselves. For instance, the fact that all objects either contain some gold or do not contain any gold is a fact that has even more necessity than a law of nature does. It is still a fact even in the Star Trek universe, where the laws of nature are different (since starships routinely accelerate beyond the speed of light). For 4 to be a prime number is likewise impossible even in the Star Trek universe. It would require more than merely a violation of the laws of nature.
The laws of nature, then, fall somewhere between the accidental facts (which lack the laws’ necessity) and the facts that possess a stronger variety of necessity than the laws do. The laws are distinguished by having the variety of necessity that distinguishes the laws. But we must do better than that if we are to understand what a law of nature is.
Philosophers do not aim to discover the laws of nature. That’s a job for scientists. What philosophers aim to do is to figure out what sort of thing scientists are discovering when they discover the laws of nature. The philosopher’s aim is not to help scientists do their job. Instead, the philosopher’s aim is to better understand the job that scientists are doing. For instance, when scientists explain why something happens by appealing to a law of nature that they have discovered, what makes a law able to answer such a ‘Why?’ question? To understand scientific understanding is a job for the philosophy of science.
Of course, it can be difficult to reach this philosophical understanding, and I will ask you to bear with me as I guide you – step by step – towards understanding what a law of nature is. I hope that as a useful byproduct, you will also enjoy seeing how a philosopher utilises a few bits of logic (paging Mr Spock!) to grapple with the question ‘What is a law of nature?’ Hold on: I hope you will find the final result to be elegant and illuminating... (MORE - details)