Is "If A then B" equal to "B if and only if A"?
Is "If A then B" equal to "B if and only if A"?
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58 comments
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If Nazi, then fascist = true
Fascist, if and only Nazi = not true
If car, then vehicle = true
Vehicle if and only if car = not true
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I used the bananas are fruits analog but your one works well too!
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I just figured with Lemmy’s interest in politics it seemed like an obvious example. I threw in the car because I didn’t want to be that guy who makes everything about nazis…
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Yeah careful with that, the logic example Nazis will be all over you if you don't mix it up some.
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Not everything is about Nazis, Boinkage, geez…
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If car, then vehicle = true
Car if and only if vehicle = true.
Is this correct?
Therefore "If A then B" = "A if and only if B" (or "If B then A" = "B if and only if A")?
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B can still be true when a is false. iff means that b can only be true when a is true.
Also, the equivalent statement is.
vehicle if and only if car.
not
car only if vehicle
since a truck is a vehicle, the statement is false.
Somewhat wrong above:
A B a iff b
T T T
T F F
F T F
F F T
look online for truth tables.
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You’d have to firm up your definition of car and vehicle before you could decide that one. Does a hot wheels car count as a car? Does a vehicle have to be large enough to move people or freight?
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Don't confuse this guy with ontological questions.
This is straight truth table level stuff.
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58 comments