There is a theory that if an image needs explaining then it has failed. I think this is horse shit: Seems to smell nice and is supposed to be useful, but actually doesn’t bear a lot of close inspection… and then it turns out that it’s not even useful until it has rotted down for a year. Am I stretching the metaphor? Probably.
Anyway, my point is this: there are very few images that do not already come with explanatory baggage, even if it is not explicitly printed underneath the image for us to read. Many of the most well known photographers are also well published and these days are almost always also bloggers, and so their own particular motivations and predilections are well known ( or at least easily discoverable for someone wanting to find out more about why a particular photo may have been taken ). Many images exist as part of a homologous body of work or even a personal project ( everyone is doing them these days ), and so are given context by the other images in the set. Many other images don’t need context because they fall easily into an already well recognised category of imagery ( what separates genuine appreciation of an awesome landscape from “location bagging” is a subject I will probably return to ). These images might even get mis-understood, but at least the viewer will THINK they know what they are looking at.
Then there a the few remainders. Images that do not fit easily into an already existing group ( and these are often the ones that will catch our attention in the first place ). Those that do not benefit from being under the umbrella of some kind of mission statement that covers a group of images. Those about which little is known of the author. I think it is perfectly acceptable for them to be accompanied by a few words of explanation.
We should not forget that during the great evoluative phases of their medium, painters often painted more for the cognoscenti than for than the general public, and so they painted in the knowledge that their audience would understand what they were trying to do. They often allied themselves with “schools” which had more or less explicit goals. Or they worked in isolation and went mad. The great evoluative phase that is the web means that isolation is a thing of the past ( unless you seek it ), but it also means you have no idea who will be looking at your work, what their age or experiences may be, or what part of the world they are from. Of course certain images might be said to ‘speak for themselves’, but I am not sure that how loudly they speak does not depend on our familiarity with the medium or the subject matter, and in any case them speaking does not preclude a caption, we can always choose not to read it.