In this essay, Drengson develops some typologies of technology and philosophy. He first presents four possible understandings of "philosophy" and argues that philosophy is best understood as "a sort of jazz played with concepts." He further identifies four stages of technological development: Technological anarchy, technophilia, technophobia, and appropriate technology. The central criterion of demarcation is the dominant human attitude toward technology in each stage. Technological anarchy is a playful, anything goes stage, when the possibilities of technology are explored and when there is no dominant standard. Technophilia is the love of, and in some cases identification with technology. In this stage, as in the early stages of a love affair, one often will not notice the downsides, limits, and problems of technology. The "personation" discussed by Doug Browning is a good example of technophilia. Technophobia is a fear or hatred of technology. It goes beyond a reasoned awareness of negative effects and tends toward rejection. Dreng-son argues that appropriate technology, as a self-critical stage and attitude, is the most mature and philosophically rich. Appropriate technology urges us to balance all costs, maintain biodiversity, promote benign interactions between humans, non-human animals, and technology, and to promote human development. This view captures many of the insights and goals of current programs of sustainable development and sustainable, or green, engineering and design.