In the process, we learned to demonstrate the validity or invalidity of arguments with truth tables. We also learned to demonstrate the validity of arguments with proofs. Unfortunately, not all intuitively valid arguments can be represented as valid in statement logic. All oaks are plants.
All plants are trees.
Therefore, all oaks are trees. Therefore, T. But this argument form clearly leads to invalid arguments. Therefore, unicorns exist. Hence, the argument form is invalid . But we know the original argument to be valid .