Making sense of the theme of aspects in Wittgenstein's later philosophy requires understanding its origins in his earlier philosophy. The theme originates as a drastic refashioning of Russell's notion of acquaintance. Whereas Russellian acquaintance draws us to the private realm of aspects as sense-data, its refashioning in Wittgenstein returns us to the activity of characterizing.
Wittgenstein was not willful with his articulations. The attempt to characterize what characterization itself consists in – an essentially logical, as well as philosophical project – forced him to qualify, position, and exploit the words “aspect” and “as” over and over again. In Wittgenstein's hands as- and aspect-phrasing draw in modes, manners, and modalities from the beginning, as in Russell they did not.
In characterizing such-and-such as so-and-so we draw out an aspect or way in which things are. Objects and properties are not sums or law-like collections of aspects, and aspects are orthogonal to values. Aspects are there to be seen, not “merely subjective,” purely epistemic, or conventional in character.
Wittgenstein's uses of as- and aspect-phrasing do invite the charge that he confused talk about essence with essence, necessity with grammar, sign with object, truth with stipulation. But he was pursuing the reverse idea, committed to fulfilling the analytical role played by Russellian acquaintance. Wittgenstein takes as- and aspect-phrasing to serve us essentially in our ability to draw meaningful distinctions between characterizations and properties, discoveries and inventions, appearances and realities. They thereby open up space for the kinds of discoveries it is possible to make in philosophy. That there is such a thing as insight into things and people, into possibilities that are not necessities, into truths and falsehoods – that these are not merely intuitions or appearances or conventions – these are among Wittgenstein's deepest philosophical themes.
The refashioning of Russellian acquaintance involved two major tasks. The first was to resurrect our working modal notions of possibility and necessity. Frege, Russell, and Moore had attempted to eliminate them from philosophizing about logic, working only with the notion of (actual) truth. Wittgenstein reprises this.