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If me turning on the light is a necessary condition for the light being on, then it implies that if I did not turn on the light the light is off. To be pedanti

If me turning on the light is a necessary condition for the light being on, then it implies that if I did not turn on the light the light is off. To be pedantic, it’s not quite that either. The logic theorem states if A => B then !B => !A. The => means that A is sufficient for B, because “false => true” evaluates to “true” but “true => false” evaluates to “false”. If it were “necessary”, those statements would evaluate the opposite way. This means that if me turning on the lights is sufficient for the light being on, then the light being off is sufficient to deduce that I did not turn it on.

cycomanic 5y ago
I don't think you're contradicting my post. You are simply stating that me turning on the light is not a necessary condition, but a sufficient condition (which is a reasonable argument). My argument was that if the statement "if the light is on it was turned on by me" is true (i.e. the me turning on is a necessary condition), then if I did not turn on the light the light is off [edited after mistyping before]. I think this works better with other examples, because as you state, we typically think more of the turning on as a sufficient condition.
- munchbunny 5y ago
  I don't think you're contradicting my post. Yes, it wasn’t my intent to contradict your overall point, just to correct your logic. My argument was that if the statement "if the light is on it was turned on by me" is true (i.e. the me turning on is a necessary condition) then it follows that if the light is off, I have not turned it on. I disagree with you here. The counterfactual, or at least the logic theorem, for the statement [light is on] => [I turned the light on] (me turning it on is necessary for it to be on) is [I did not turn the light on] => [the light is not on] That’s sound, though it’s not a particularly insightful leap of logic. If you translate this to the author’s point, they’re basically saying that !A => !B doesn’t tell you that A => B. And that’s correct as far as Boolean logic goes. I am unclear on whether we disagree on that point.
  - cycomanic 5y ago
    Sorry I edited my post just after posting it, because I realised I wrote it the wrong way around (too many nots and light switches ;). You managed to reply just in between. >I disagree with you here. The counterfactual, or at least the logic theorem, for the statement [light is on] => [I turned the light on] (me turning it on is necessary for it to be on) is [I did not turn the light on] => [the light is not on] Yes you're correct and that's what I corrected my statement to where you managed your reply in between. However my original statement was: >If me turning on the light is a necessary condition for the light being on, then it implies that if I did not turn on the light the light is off. so A=>B therefore !B=>!A. Where A == "light is on", and B == "me turning light on". I agree that it's not particularly insightful. My point was regarding the statement "The whole point of the article is that you can't get causality from things that didn't happen" from the OP I replied to. That's just not true, we can make statements about causality for things that didn't happen, because we can deduce them from logical conditions. >If you translate this to the author’s point, they’re basically saying that !A => !B doesn’t tell you that A => B. And that’s correct as far as Boolean logic goes. I am unclear on whether we disagree on that point. Although we agree in principle I disagree what you say is the authors point. From the article: >They [counterfactuals] express wishful thinking about an alternate history where the bad event didn’t happen. Because they represent “events that didn’t occur” they cannot have caused anything. This is a statement I disagree with. To me that sounds that the author essentially says we can not make statements of the type of !A => B (or !B). To me that is wrong and also not a counterfactual. Counterfactuals, are statements about a hypothetical event, i.e. "If I had not turned the light on it would be off now". To me though the author seems to extend the definition of counterfactuals to mean "events that did not happen", maybe he means the correct thing, but both his words and examples do not reflect the correct meaning IMO

cycomanic 5y ago

I don't think you're contradicting my post. You are simply stating that me turning on the light is not a necessary condition, but a sufficient condition (which is a reasonable argument). My argument was that if the statement "if the light is on it was turned on by me" is true (i.e. the me turning on is a necessary condition), then if I did not turn on the light the light is off [edited after mistyping before]. I think this works better with other examples, because as you state, we typically think more of the turning on as a sufficient condition.

munchbunny 5y ago
I don't think you're contradicting my post. Yes, it wasn’t my intent to contradict your overall point, just to correct your logic. My argument was that if the statement "if the light is on it was turned on by me" is true (i.e. the me turning on is a necessary condition) then it follows that if the light is off, I have not turned it on. I disagree with you here. The counterfactual, or at least the logic theorem, for the statement [light is on] => [I turned the light on] (me turning it on is necessary for it to be on) is [I did not turn the light on] => [the light is not on] That’s sound, though it’s not a particularly insightful leap of logic. If you translate this to the author’s point, they’re basically saying that !A => !B doesn’t tell you that A => B. And that’s correct as far as Boolean logic goes. I am unclear on whether we disagree on that point.
- cycomanic 5y ago
  Sorry I edited my post just after posting it, because I realised I wrote it the wrong way around (too many nots and light switches ;). You managed to reply just in between. >I disagree with you here. The counterfactual, or at least the logic theorem, for the statement [light is on] => [I turned the light on] (me turning it on is necessary for it to be on) is [I did not turn the light on] => [the light is not on] Yes you're correct and that's what I corrected my statement to where you managed your reply in between. However my original statement was: >If me turning on the light is a necessary condition for the light being on, then it implies that if I did not turn on the light the light is off. so A=>B therefore !B=>!A. Where A == "light is on", and B == "me turning light on". I agree that it's not particularly insightful. My point was regarding the statement "The whole point of the article is that you can't get causality from things that didn't happen" from the OP I replied to. That's just not true, we can make statements about causality for things that didn't happen, because we can deduce them from logical conditions. >If you translate this to the author’s point, they’re basically saying that !A => !B doesn’t tell you that A => B. And that’s correct as far as Boolean logic goes. I am unclear on whether we disagree on that point. Although we agree in principle I disagree what you say is the authors point. From the article: >They [counterfactuals] express wishful thinking about an alternate history where the bad event didn’t happen. Because they represent “events that didn’t occur” they cannot have caused anything. This is a statement I disagree with. To me that sounds that the author essentially says we can not make statements of the type of !A => B (or !B). To me that is wrong and also not a counterfactual. Counterfactuals, are statements about a hypothetical event, i.e. "If I had not turned the light on it would be off now". To me though the author seems to extend the definition of counterfactuals to mean "events that did not happen", maybe he means the correct thing, but both his words and examples do not reflect the correct meaning IMO