What does Shingo refer to inventory as?

Shingo refers to inventory as "evil" because he views excessive inventory as a symptom of inefficiency within a production system. The concept stems from the idea that holding large amounts of inventory ties up capital and can mask underlying problems in the processes, such as production inefficiencies or quality issues.

In lean manufacturing philosophy, which Shingo significantly contributed to, reducing inventory is a primary goal because it allows for quicker responses to customer needs and helps highlight areas where improvement is needed. Thus, inventory is seen not as a beneficial asset, necessity, or resource, but rather something that should be minimized to enhance efficiency and streamline operations. This perspective urges organizations to strive for just-in-time methodologies, pushing toward maintaining only what is necessary for immediate production needs and customer demands.