> there's no reason to make others redo work. As a simplified example, consider Corporation G and Corporation P. One will eventually lose market share to the o

> there's no reason to make others redo work. As a simplified example, consider Corporation G and Corporation P. One will eventually lose market share to the other, go bankrupt, and be replaced by Corporation R that bases its business practices on the more successful one (then the cycle repeats). Both are evil, as corporations are wont to be, and in particular will never release anything under a less restrictive licence than they have to (so they will never release software under a MIT licence). However, G will release software under the GPL if this allows it to save work, whereas P will always release software under a proprietary licence, even if this forces it to expend more resources rewriting GPL functionality. Releasing code under the GPL exerts a selection effect that favors G over P, and in the long run results in corporations that release somewhat more software period - and significantly more software under FOSS licences - than if P was not forced to redo work.