S1 <=> S2
^ ^
v v
~S2 <=> ~S1
This Greimas square explores the opposites of concrete and abstract, using photography as a context. In the Greimas square, these are the S1 and S2 concepts. The ~S1 concept is “not concrete”. The ~S2 concept is “not abstract”. The Greimas square for deriving new concepts or relations comes from relabeling the ~S1 and ~S2 with a more descriptive and less logical label. So here is an analysis to suggest some better words for ~S1 and ~S2.
A concrete photo is of something you would see more or less as-is.
The abstract is the pattern or idea independent of any concrete elements within it.
What is an example of something not abstract yet not quite concrete either? For a photo, a blur comes to mind. A blur photo focuses on one element of the photo and blurs out the rest. The rest is the suggestion of something concrete.
What is an example of something not concrete yet not quite abstract either? I think when the pattern of the elements is more important than the elements themselves. Concrete elements are still visible, but you are drawn to the pattern they create rather than the real elements that compose them. Emergence suggests a new pattern from concrete elements. When does the pattern become abstract? The pattern implies regularity but some of the best abstractions have irregular patterns if you can even call them that. Irregular patterns? Abstract nature? Sorry, this whole topic exudes oxymoron. A pure abstract photo would have no concrete elements in it.
Concrete <=> Abstract
^ ^
v v
Blur <=> Emergence
Concrete and abstract are the foundation concepts. Blur and emergence complete the square. Blur focuses your attention on something concrete while the background gives implied context. Emergence focuses your attention on the pattern but is created by concrete elements.
The concrete is a picture of you standing next to a lit Christmas tree. The blur is you with the Christmas tree blurred in the background, or possibly you blurred out and the tree in focus if the photographer doesn’t much care for you. The emergent is the Christmas tree blurred to bokeh with the lights as or more important than the contents, namely you. And the abstract is a bokeh Christmas tree with only the form of the tree suggested by the pixelated lights.
Of course, categorization is never definitive when it comes to concepts. Probably the most important concept is that you enjoy the picture.