Dogs, we might suppose, dream of having hands. Seeing my dog Rufus stare longingly at a doorknob or struggle with nose and paws to open or examine some recalcitrant object, I can easily imagine how his life would be transformed by the divine gift of a firm grasp combined with flexible fingers.

When I face a new and frustrating problem or situation, I sometimes feel like Rufus must feel without hands. Whether it is a technical problem, a scientific or philosophical question, or a personal conundrum, I feel clumsy and awkward. I cannot take things apart in a way that makes sense or see which things matter and which do not. All of my accustomed ways of approaching problems either skitter across the surface of the puzzle before me or merely grab corners of it without leverage.

As hands are to motions, models are to thoughts. Models connect our thoughts to the worlds around us and ease or enable our actions in those worlds. Like hands, our models extend the strength, dexterity, reach, and reliability of our thoughts, plans, and dreams. We think with our models just as we move with our limbs and just as we cannot move very far without our limbs, we cannot think very far without our models.

When I feel like Rufus without hands, my problem is that I don't have good models of my new situation. Good models are as much a part of us as our hands and fingers and while they may be nearly invisible or unconscious as we use them from day to day, we acutely notice their absence. This book is about how to think about the models we think with. And it begins a discussion about how to change the models we think with when they no longer fit the problems before us.