What's the Difference Between Validity and Soundness in Logic?

The points I want to make about logic in this post are simple. Two introductory things that students usually learn about in logic are validity and soundness. Deductive validity is defined by many logicians as "If the premises of an argument are true, then the conclusion is necessarily true." Note that this kind of validity deals with a hypothetical--"if" the argument is true. Validity does not tell us whether an argument is true or not and in today's logic classes, we teach students symbolic logic, which makes the exercise even more abstract. But to give an example of validity, let's suppose that someone asserts, "If Fido is a dog, then Fido is a canine; Fido is a dog; therefore, Fido is a canine."

Is this argument deductively valid? According to the canons of formal logic, it is. I could explain why later but the bottom line is that if the premises of this argument were true, then the conclusion of the argument would necessarily follow from the premises, which happens to be the case. Ergo, the argument is deductively valid, but is this argument sound? Soundness means that an argument is valid and the premises are true. Given that these conditions are met in the argument concerning Fido, the argument is both valid and sound. However, I've found that soundness is harder to determine: validity is relativity easy to ascertain. For more information, see https://fosterheologicalreflections.blogspot.com/2018/03/some-definitions-for-logic-terms.html