Logical implication

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Logical implication (also known as implies, or If ... then) is a logical operation. It takes two arguments. It returns false, only if the first term is true, and the second term is false.

This may be problematic, because it means that from a false proposition, anyithing can follow.

[edit] Examples

The following shows a (valid) implication

  1. All humans are mortal (they die).
  2. Aristotle is human
  3. Therefore Aristotle is mortal


Now look at If I am healthy, I will come to class. There are four possibilities

  1. I am healthy, and I come to class. I have kept my promise.
  2. I am healthy, and I do not come to class. I have not kept my promise
  3. I am not healthy, and I do come to class. I have kept my promise.
  4. I am not healthy,and I do not come to claaa. I have kept my promise.
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