Abstract: Economic growth was born only in a human culture in a particular moment of its history and is not a "natural push of mankind". It grew up in a culture with a completely anthropocentric background, which considers our species above (out of) Nature and independent from the Ecosystem: it originated from a worldview that sees human activities as possible regardless of their link with the rest of Nature, considered as "human environment". So economic growth does not take into account the way of life of the Earth, based on closed cycles and a steady-state situation.
A culture can persist indefinitely only if it has "modes" of the steady-state type: in present Western civilization degrowth is essential for achieving a transition to a situation of that type, with a number of humans and consumption very lower than the current ones, which are not compatible with Earth Life.
The recently born Degrowth movement too often remains on an anthropocentric background. It does not deal with philosophical issues, but an economic degrowth is impossible if you keep an anthropocentric worldview, until you consider man out the Biosphere and unique source of values: so it can be very hard to leave the fixed idea of the perennial increase of material goods.
Ecology as understood by general thought, also known as shallow ecology, does not change the background thought of Western culture: it requires only to reduce pollution as much as possible and save some natural areas for the benefit of man. It consider the Earth as the house of man: in essence, everything can go on as before, with some changes and some technical device.
Instead Deep Ecology (or Ecosophy) is a thought movement, a worldview that requires a background of pantheistic reverence for all sentient beings and for the relationships that connect them to each other and to the so-called "inanimate world". It does not give a particular value to our species, fully considered part of Nature. It is very difficult to accept economic degrowth, as necessary transition to achieve a steady state, without a philosophical base very different from that of present Western civilization, based on a widespread and deep anthropocentrism: what is breathed from birth seems obvious, and therefore does not appear at all. Substantially, for accepting degrowth, we must have a strong transition from an anthropocentric to an ecocentric worldview, that is the idea of Deep Ecology, a philosophy that requires a pantheistic reverence for all sentient beings and has for first value the good health of the Whole Ecosystem.

Contribution to the 3rd International Degrowth Conference for Ecological Sustainability and Social Equity in Venice in 2012.

Italian version below