Implication (logic)

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Implication (also known as implies, or If ... then) is a logical operation. It takes two arguments. It returns false, if and 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, anything can follow.

Examples[change | change source]

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 promise 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. (However, grammar is unclear about this)
  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 class. I have kept my promise.

Related pages[change | change source]