This book grew out of my confusion. If logic is objective how can there
be so many logics? Is there one right logic, or many right ones? Is
there some underlying unity that connects them? What is the significance
of the mathematical theorems about logic which I've learned if they have
no connection to our everyday reasoning? The answers I propose revolve
around the perception that what one pays attention to in reasoning
determines which logic is appropriate. The act of abstracting from our
reasoning in our usual language is the stepping stone from reasoned
argument to logic. We cannot take this step alone, for we reason
together: logic is reasoning which has some objective value. For you to
understand my answers, or perhaps better, conjectures, I have retraced
my steps: from the concrete to the abstract, from examples, to general
theory, to further confirming examples, to reflections on the
significance of the work.