This post is an excerpt from Chapter 7 of Systems Thinking Made Simple. A New Kind Of Logic There is always an underlying logic implicit in both informal and formal systems thinking methods. Making the logic explicit leads to clarity of thought and deeper understanding of concepts. Logic is any system of principles that guides one’s thinking. It need not be formalized or even conscious. All of us use logic every day without an awareness of what it is or where it came from. Systems thinking as a method also has an underlying logic.