If I may, isn't the ultimate "context" the time and place where anyone has happened to live, especially concerning philosophy? Sure, there can be intellectual value in the 'knowledge' people have previously obtained, but it is always informed by that context. Ancient Athens had slavery and women were completely devalued, neither of which was flatly rejected by Plato or Aristotle. In John Locke's lifetime the unconstrained "Divine Right" of monarchs was still taken seriously by many people, which informed his determination to make liberty (freedom from the arbitrary will of any person) the predicate of justice--which can be shown to be inconsistent within his own thinking: if injustice is being subject to the arbitrary will of any other person, the most immediate inference for justice is that everyone must refrain from subjecting any other person to one's own arbitrary will, which makes mutual respect the predicate of justice. Karl Marx was born into a land (Prussia) that was still feudal, where property is the most important material thing, and he failed to see that during his lifetime money became more economically important than property (as "wage slavery" replaced bondage slavery and serfdom for supplying labor for enterprises of mass production).

It seems to be all but impossible to transcend that constraint. Yet, progress is made: knowledge does increase, even concerning philosophical matters.