A Change In Plans

I discovered some errors in the textbook that I've been working through. I now distrust the predicate logic presented there. All of the mathematical theories are correct so far as I can tell. So, I shall return to it after I establish a strong understanding of predicate calculus through other textbooks. Philosophical logic is an excellent method to learn prior to learning mathematical logic. So, I shall approach predicate calculus from this angle first as I did with propositional logic.