@heather Well, it's not a question that comes up often ordinarily (and it is actually more subtle to answer than one might think), but the standard foundation goes like this: We have to start
somewhere, so we define logical expressions "manually" by what is called a
truth table. It's a lookup table that tells you what the logical operator (like 'and', 'if', 'or') yields for any given combination of truth values for its input