Images as Evidence
You will often see images offered as concrete proof that a claim is true. However, despite the cliche, the camera can lie. To evaluate the support that an image lends to a claim, there are three criteria that you need to bear in mind: relevance, significance, and selectivity.
Relevance
The first criterion is relevance. For an image to support a claim, it must depict all of the key ideas contained in the claim. It it doesn’t relate to any part of a claim, then it can’t prove the claim. Obviously, relevance is a matter of degree, but the more relevant an image is to a claim, the better the evidence that it provides.
Significance
The second criterion is significance. This concerns how much interpretation of the image is necessary; does the image speak for itself, or must we make assumptions about it in order for it to support the claim?
Selectivity
The third criterion is selectivity, which is to do with how representative the image is. If a general claim is supported by an image of a specific example, then we have to ask whether the example in the image is typical. It may be that it has been carefully selected to support a point, when actually most examples would go against it.