Definitely a repost, but it fits the season

  • NeatNit@discuss.tchncs.de
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    18 hours ago

    The comment you replied to is my response to this. It’s the only boolean operation that works this way. All the others are straightforward.

    • Klear@quokk.au
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      18 hours ago

      I think the problem is that you’re thinking in terms of boolean algebra, while implication being implication comes from propositional logic.

      • NeatNit@discuss.tchncs.de
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        17 hours ago

        That’s interesting. I’ll have to read up on that. You’re right, I am thinking about boolean algebra.

        In the mean time though, I’ll note that Boolean algebra on Wikipedia also refers to this operation, so I’m not alone:

        Material conditional

        The first operation, x → y, or Cxy, is called material implication. If x is true, then the result of expression x → y is taken to be that of y (e.g. if x is true and y is false, then x → y is also false). But if x is false, then the value of y can be ignored; however, the operation must return some Boolean value and there are only two choices. So by definition, x → y is true when x is false (relevance logic rejects this definition, by viewing an implication with a false premise as something other than either true or false).

        It also uses the second interpretation that I mentioned in my earlier comment (4 above this one), with true being default, rather than the one we’ve been discussing.