digital forgetting
Harvard professor Viktor Mayer-Schönberger argues for an expiration date on digital content. While in practice the idea (a metatag for all data saying "will self-destruct at such and such a date") might sound unfeasable, his analysis of what he calls our "temporal version of a panoptic society" is interesting:
As humans we have the capacity to remember - and to forget. For millennia remembering was hard, and forgetting easy. By default, we would forget. Digital technology has inverted this. Today, with affordable storage, effortless retrieval and global access remembering has become the default, for us individually and for society as a whole. We store our digital photos irrespective of whether they are good or not - because even choosing which to throw away is too time-consuming, and keep different versions of the documents we work on, just in case we ever need to go back to an earlier one. Google saves every search query, and millions of video surveillance cameras retain our movements.
Of course, many have written on this theme - for instance Lawrence Lessig, from the perspective of intellectual property laws. But whereas Lessig mostly discussed how to deal with all our digital information (and who owns it), Mayer-Schönberger's suggestion is more radical: we shouldn't want to keep everything. Forgetting needs to become the default again, so that we have to consciously decide what to remember and for how long.
Extrapolating a bit, his idea about digital forgetting really sounds like the psychological self-defence strategy of a society traumatized by information overload.
(Or, less pathological, it may just be a good incentive to clean up your hard disk.)
See Mayer-Schönberger's research paper 'Useful Void: The Art of Forgetting in the Age of Ubiquitous Computing', as well as this interview (in German).