I'm looking for a (possibly introductory) textbook on logic that covers the motivation behind conventions in logic, like the definition of the implication. Prof. J. Lau has an excellent webpage, critical thinking web, on which he provides the sort of treatment I'm looking for. Example; material conditional. Thorough, rigourous, pedagogical without compromising on the maths.
Is there a textbook out there that adheres to these requirements? Too often do I read things like "the teacher didn't lie when she..." when authors attempt to motivate the truth table behind the material conditional. Others, like Enderton, only briefly touch on an explanation that more often than not lacks the satisfactory insight that explanations like Lau's provide.
I hope this is clear enough to give you an idea of what I'm after.
