Lafari@lemmy.world to No Stupid Questions@lemmy.world · 6 months agoIs "If A then B" equal to "B if and only if A"?message-squaremessage-square74fedilinkarrow-up140arrow-down19
arrow-up131arrow-down1message-squareIs "If A then B" equal to "B if and only if A"?Lafari@lemmy.world to No Stupid Questions@lemmy.world · 6 months agomessage-square74fedilink
minus-squareLafari@lemmy.worldOPlinkfedilinkarrow-up3·6 months agoThanks. Could you possibly elaborate? Why are they not equal?
minus-squareBoinkage@lemmy.worldlinkfedilinkarrow-up7arrow-down1·edit-26 months agoSubstitute common sense terms. If I say “if it is an apple, it is a fruit”, does it then follow that a thing is a fruit if and only if it is an apple? No. Lots of other things are fruit without being an apple.
minus-squareRhynoplaz@lemmy.worldlinkfedilinkarrow-up1·6 months agoBetter read that one again. “If B then A” … “B if and only if A”? If Apple then fruit. Is Apple ONLY if it’s a fruit. This one actually checks out.
Thanks. Could you possibly elaborate? Why are they not equal?
Substitute common sense terms. If I say “if it is an apple, it is a fruit”, does it then follow that a thing is a fruit if and only if it is an apple? No. Lots of other things are fruit without being an apple.
Better read that one again.
If Apple then fruit. Is Apple ONLY if it’s a fruit.
This one actually checks out.