From "What do Lindsay Lohan and Wittgenstein have in common?" by Sarah Nardi
"And that, patient reader, brings us to Wittgenstein, who began the Tractatus with the proposition "The world is everything that is the case." It sounds simple enough on its face but think about it long enough and it's a devastating mindfuck. How can we ever know with certainty what is or is not the case? Language? Language is a social construct. If you and I agree that the sky is blue, is it necessarily the case that the sky is blue? What is blue, really? It's a sound we've all agreed to make in reference to a visual phenomenon. But because what we've all agreed to call blue can only be perceived on an individual sensory level, how can we know with certainty that we're all perceiving the same thing in the same way? Follow this thinking long enough and you may end up where Wittgenstein once did, believing that we can never know with certainty anything beyond ourselves. We can't know anything of the external world because we can't confirm anything as objectively being the case.
I often think of Wittgenstein when considering photography because much in the way we assume words correspond to reality, we think of photographs as representations of objective truth. Photography is the medium of documentary, after all. And though we all know it can be staged and manipulated according to the photographer's point of view, we assume that photography, to a significant degree, captures elements of reality as they objectively exist. But does it? Is there any such thing as an objective reality or does everything in our world rely on the context that we ourselves create?"