Hi, thanks for the question. I am using the term ‘counterfactual’ (admittedly somewhat loosely) to describe facts that refer to whether things are possible or impossible, regardless of whether they actually happen.
In the first post, I claimed that it is only meaningful to say that the lamp transmits information if it is possible for the lamp to be a in a different state. Conversely, if the lamp was broken, then it is impossible for the lamp to be in a different state, and information does not get transmitted. If you just describe the system in terms of what actually happens (ie. ‘the lamp is on’), you miss out on this fact. In the first post, I called statements about what actually happens in the system ‘factual statements’, and statements about what is possible/impossible ‘counterfactual statements’.
Similarly, in the case of the perpetual motion machine, you can make a factual statement about what actually happens (ie, some gears turn around and eventually the machine stops moving, failing to achieve perpetual motion), or you can make a counterfactual statement (that it is impossible to make perpetual motion machine, regardless of the specifications of that machine). In this post, I again claimed that just making the factual statement misses out on the important counterfactual claim.
Of course, in the first post, when the lamp is broken, and we say it is ‘impossible’ to send another signal, this is specified by the parameters of the thought experiment, rather than the laws of physics (in practice, the laws of physics might not prevent you from fixing the lamp, for example). Whereas in the this this post, when we say it is ‘impossible’ to build a perpetual motion machine, the restriction does come from the laws of physics.
I think that it is the best word to use. When used as an adjective Collins defines ‘counterfactual’ as ‘expressing what has not happened but could, would, or might under differing conditions ‘. I think that this fits the way I was talking about it (eg. when referring to ‘counterfactual laws’). In the first post, I talk about whether the lamp ‘could would, or might’ have been in a different state. In this post, we talk about whether a perpetual motion machine ‘could would, or might’ work if it was made using a different configuration. (maybe some of the confusion comes from using ‘counterfactual’ as both an adjective and a noun?)
Though if you have any suggestions on other words that might be clearer, let me know.
I’m bothered by something else now: the great variety of things that would fit in your category of counterfactual laws (as I understand it). The form of a counterfactual law (“your perpetual motion machine won’t work even if you make that screw longer or do anything else different”) seems to be “A, no matter which parameter you change”. But isn’t that equivalent to “A”, in which case what makes it a counterfactual law instead of just a law? Don’t all things we consider laws of physics fit that set? F=ma even if the frictionless sphere is blue? E=mc^2 even if it’s near a black hole that used to be Gouda cheese?
The form of a counterfactual law (“your perpetual motion machine won’t work even if you make that screw longer or do anything else different”) seems to be “A, no matter which parameter you change”.
I don’t think this is right. As I am using it, ‘counterfactual’ refers to a statement about whether something is possible or impossible. Statements of the form “A, no matter which parameter you change” are not always like this. For example if A=’this ball has a mass of 10kg’. This is not a statement about what is possible or impossible. You could frame it as ‘it is impossible for this ball to have a mass other than 10kg, no matter which parameter you change’, but doesn’t give us any new information compared to the original statement.
Another important feature is that the impossibility/possibility is not restricted to specific dynamical laws. In your example ‘F=ma, even if the frictionless sphere is blue’, this statement is only true when Newton’s laws apply. But the statement ‘it is impossible to build a perpetual motion machine’ refers, in principle, to all dynamical laws-even ones we haven’t discovered yet-which is why principles like this may help guide our search for new laws.
Hi, thanks for the question. I am using the term ‘counterfactual’ (admittedly somewhat loosely) to describe facts that refer to whether things are possible or impossible, regardless of whether they actually happen
Standardly, a counterfactual didn’t happen.
The term that means “whether things are possible or impossible, regardless of whether they actually happen” is “modal”.
I didn’t use ‘modal’ because that is used to refer to logical possibility/impossibility, whereas I am interested in referring to physical possibility/impossibility. Depending on your philosophical views, those two things may or may not be the same.
Hi, thanks for the question. I am using the term ‘counterfactual’ (admittedly somewhat loosely) to describe facts that refer to whether things are possible or impossible, regardless of whether they actually happen.
In the first post, I claimed that it is only meaningful to say that the lamp transmits information if it is possible for the lamp to be a in a different state. Conversely, if the lamp was broken, then it is impossible for the lamp to be in a different state, and information does not get transmitted. If you just describe the system in terms of what actually happens (ie. ‘the lamp is on’), you miss out on this fact. In the first post, I called statements about what actually happens in the system ‘factual statements’, and statements about what is possible/impossible ‘counterfactual statements’.
Similarly, in the case of the perpetual motion machine, you can make a factual statement about what actually happens (ie, some gears turn around and eventually the machine stops moving, failing to achieve perpetual motion), or you can make a counterfactual statement (that it is impossible to make perpetual motion machine, regardless of the specifications of that machine). In this post, I again claimed that just making the factual statement misses out on the important counterfactual claim.
Of course, in the first post, when the lamp is broken, and we say it is ‘impossible’ to send another signal, this is specified by the parameters of the thought experiment, rather than the laws of physics (in practice, the laws of physics might not prevent you from fixing the lamp, for example). Whereas in the this this post, when we say it is ‘impossible’ to build a perpetual motion machine, the restriction does come from the laws of physics.
Hope this helps clear things up!
Confusion removed; you were using “counterfactual” in a way I had never seen here or anywhere else. (Is that the best word, though?)
Glad that confusion is removed!
I think that it is the best word to use. When used as an adjective Collins defines ‘counterfactual’ as ‘expressing what has not happened but could, would, or might under differing conditions ‘. I think that this fits the way I was talking about it (eg. when referring to ‘counterfactual laws’). In the first post, I talk about whether the lamp ‘could would, or might’ have been in a different state. In this post, we talk about whether a perpetual motion machine ‘could would, or might’ work if it was made using a different configuration. (maybe some of the confusion comes from using ‘counterfactual’ as both an adjective and a noun?)
Though if you have any suggestions on other words that might be clearer, let me know.
I’m bothered by something else now: the great variety of things that would fit in your category of counterfactual laws (as I understand it). The form of a counterfactual law (“your perpetual motion machine won’t work even if you make that screw longer or do anything else different”) seems to be “A, no matter which parameter you change”. But isn’t that equivalent to “A”, in which case what makes it a counterfactual law instead of just a law? Don’t all things we consider laws of physics fit that set? F=ma even if the frictionless sphere is blue? E=mc^2 even if it’s near a black hole that used to be Gouda cheese?
I don’t think this is right. As I am using it, ‘counterfactual’ refers to a statement about whether something is possible or impossible. Statements of the form “A, no matter which parameter you change” are not always like this. For example if A=’this ball has a mass of 10kg’. This is not a statement about what is possible or impossible. You could frame it as ‘it is impossible for this ball to have a mass other than 10kg, no matter which parameter you change’, but doesn’t give us any new information compared to the original statement.
Another important feature is that the impossibility/possibility is not restricted to specific dynamical laws. In your example ‘F=ma, even if the frictionless sphere is blue’, this statement is only true when Newton’s laws apply. But the statement ‘it is impossible to build a perpetual motion machine’ refers, in principle, to all dynamical laws-even ones we haven’t discovered yet-which is why principles like this may help guide our search for new laws.
Standardly, a counterfactual didn’t happen.
The term that means “whether things are possible or impossible, regardless of whether they actually happen” is “modal”.
https://plato.stanford.edu/entries/logic-modal/
I didn’t use ‘modal’ because that is used to refer to logical possibility/impossibility, whereas I am interested in referring to physical possibility/impossibility. Depending on your philosophical views, those two things may or may not be the same.