Everyone with a serious interest in photography grapples, at some point, with the question ‘What makes a good photograph?’
In doing so, you inevitably come to understand the wisdom of Ansel Adams’ famous remark “There are no rules for good photographs, there are only good photographs”.
Adams knew that attempting to reduce a creative process to a set of rules stands a very good chance of killing the creativity producing the magic. That is not to imply that creative expression inevitably involves breaking rules.
However, while it’s impossible to define what makes a good photograph we can learn much from asking: ‘How do photographs work’?
It seems to me that photographs ‘work’ by attempting to communicate emotions, ideas and/or evidence. Whether a specific photograph is successful in doing so is another question. Here I am simply concerned with how photographs try to communicate something to the viewer.
In what follows I’m certainly NOT suggesting the three ways I suggest photographs work are mutually exclusive. Exposition requires simplification but, self-evidently, all successful photographs combine emotion, ideas and evidence. It is not a question of presence but of priority given to one or another by the photographer.
The photograph as emotion
When photographer’s get to discussing what makes for a ‘good’ photograph, emotional appeal is almost always the first item on the list. Photography has traditionally been viewed as a medium for communicating how we see and feel about the world.
For some photographer’s emotional connection is the overriding intention. Don McCullin famously stated: “Photography for me is not looking, it’s feeling. If you can’t feel what you’re looking at, then you’re never going to get others to feel anything when they look at your pictures.” 
Certain types of photography undoubtedly rely more heavily on emotional appeal. Genres such as documentary, portraiture, war photography, wildlife and landscape all trade in emotions to varying degrees. The nature of the affective impact varies between them. Photographs of human suffering evoke sympathy and empathy while images of natural beauty inspire hope, longing and wonder.
It seems appropriate to ask what type of photographs DO NOT trade in emotions? The answer is that no photograph is devoid of emotion altogether. However, some photographers are more concerned with engaging us in a dialogue about ideas rather than appealing to our emotions.
This suggests my second way in which photographs work – as a form of self-expression.
The photograph as self-expression
Photography as self-expression obviously encompasses a wide array of styles and approaches. It can involve exploring traditional modernists concerns such as photographic processes, abstract concepts and pure aesthetics or involve explorations of some aspect of personal experience like race, ethnicity, culture, gender and sexuality.
What unites these different strategies is that the photographers are dealing in ideas. Such photography tries to communicate what the photographer thinks about some aspect of the practice of photography, their own lives, or some issue in society at large.
It is now common knowledge that all photographs are to some extent self-portraits. Every photograph simultaneously says something about the world ‘out there’ as well as the psyche of the photographer ‘in here’.
The transition from mid-twentieth century modernism to post-modernism in the 1970s is particularly associated with the abandonment of claims to objectivity in favour of explorations of subjectivity and identity. A shift from asking ‘what is going on in the world?’ to enquiring ‘how and why do I feel about what is going on in my world?’.
The public realisation of this shift, in photography, is often cited as the 1967 MoMA exhibition entitled ‘New Documents’ mounted by John Szarkowski. This featured the work of Gary Winogrand, Diane Arbus and Lee Friedlander and was seen as a turning point in prioritising the photographer’s personal engagement with the world.
It might be argued that self-expression can equally be an expression of emotion through photography. Does that mean my first two ways photographs work collapse into each other?
I don’t think so. The former type of photograph seeks to evoke an emotional response in the viewer directly, whereas the latter involves a photographer’s reflexive exploration of what it was like to experience emotions. Experiencing an emotion personally is not the same thing as having someone else describe how they felt about that same situation.
The photograph as evidence
The notion of the documentary photographer as objective witness, to events unfolding before their lens, was always a fiction. All documentary photographs are highly subjective records of events. Any act of photographing one thing rather than another implicitly states ‘this is more important than that’ (or more beautiful, or right/wrong, more valuable, or just plain interesting).
The resulting images act as evidence but, just what are they evidence of? Records of some event yes, but partial, biased, judgmental and highly selective. The role of such photographs in shaping how we interpret world events remains central. However, we know ‘the media’ is engaged in constructing narratives and photographs are selected for publication accordingly. In that knowledge, we know to be suspicious of photographs too.
It was always the case, from Roger Fenton’s early sanitised images of war through Roy Stryker’s manipulation of FSA projects by Dorothea Lange and others, to the propagandistic manipulation of ‘embedded’ war photographers in recent conflicts in Iraq and elsewhere.
Attempts to evaluate the veracity of documentary photographs must enquire as to their contexts of production and distribution more so than any other type of photography. Where we are suspicious of those contexts (media manipulation, political bias, commercial motives, etc.), our judgement will fall back on what we know about the reputation for integrity of the photographer.
The high regard in which war photographer’s such as Don McCullin, Philips Jones Griffiths and James Nachtwey are held is rightly founded on the quality of their photography but, it also hinges on our trust of them as independent minded humanitarians rather than cynical hacks photographing for coin.
All photographs deal in emotions, ideas and evidence. Depending on the intentions of the photographer, one will generally be prioritised over the others.
Whether the photographer is successful in communicating the emotion, idea, or evidence they intended is a complex question. The photographer has control over how the image is produced, and the contexts in which it is shown, but not how it will be received by a specific viewer. That reception by the viewer depends on their own subjective identity.
We owe it to serious photographers to try to understand their work on their terms not ours.
If we ‘like’ a photograph that’s great but, we don’t have to like it in order to appreciate it. Our subjective preferences are a separate thing entirely to the issue of whether a photograph is successful.
 Sleeping With Ghosts: A Life’s Work in Photography by Don McCullin (Photographer), Mark Haworth-Booth (Introduction), p.96.