Regarding depreciation, it needs to be remembered that it is a convention, not a measured physical reality. So if depreciation is 6% for a number of years and then moves up to 8% it is not because things suddenly started wearing out or becoming obsolete sooner. It is because the accounting convention changed. That change may reflect factors that have developed over a longer period of time or they might ignore factors that should be taken into consideration today. To tie depreciation back into the subject line about unproductive labor, it seems to me that rates of depreciation relate to the notion of fictitious capital to the extent that the conventional notation may understate the rate at which capital equipment may be losing value.
-- Sandwichman
