Strong and Valid Arguments

Epstein says “an argument is strong if there is some way, some possibility, for its premises to be true and its conclusion false (at the same time), but every such possibility is extremely unlikely.” A valid argument is “if there is no possible way for its premises to be true and its conclusion false (at the same time).” If an argument is not strong, it is not called valid, it would be called a weak argument.  When an argument is not valid it is called invalid. Valid and strong arguments may seem the same, but the way the whole argument is worded separates them.  A strong argument example may be “When my friends and I go to the mall, we see people only wear Vans. Therefore, all shoppers in a mall only wear Vans.” My premise can be true but conclusion may be false because I may not notice people wearing flip flops or I only visit the mall where the Vans store is. A valid version of this argument would be “People at a mall wear Vans. Therefore, every shoe on a shopper at the mall is a Vans shoe.” If people at a mall wear Vans, how can someone wear a different brand? The premise and conclusion match up, so it is a valid argument.