In Tractatus Logico-Philosophicus Ludwig Wittgenstein says that every elementary proposition is a picture.
Clearly, propositions are not visual pictures.
Dictionaries provide apt definitions of the meaning of the word "picture" as it was used by Wittgenstein:
- The main circumstances of an event or a time; the situation.
This is a generalisation of the notion of picture. Pictures in the ordinary sense also fit this definition.
A picture, broadly considered, is a representation which is not expected to be complete. It only has to bring together a few snippets of truth.
Different kinds of pictures may show different kinds of things. Photographs are not painting are not drawings.
It is clear that we must make a distinction between elementary propositions and other propositions, because we cannot consider a negation of an elementary proposition to be a picture.
I fail to see why we should make this distinction. A novel may be considered, broadly, as a very large conjunction of many elementary propositions, some negations, some disjunctions, and a novel seems indeed like a tableau about life, hence, a picture.
A painting does not explicitly use negations while propositions, at least as described using words, can. But this difference can be attributed to the various means you can use to express a proposition and propositions need not include negations.
If we insist that propositions can include negations, then perhaps we may just as well give up the notion that they are pictures. For example, it may be enough to take propositions to be logically dignified ideas or beliefs.
For example the proposition "This house is not red" would be true if "This house is blue" or "This house is gray" is true but they don`t both can be in same picture, because they are contradictory claims.
We could represent the same house twice in one picture, once blue, once gray, and therefore ... not red. The house would be represented as not red. In statements using words, "blue" does not imply "not red". In a picture, blue implies not red. And maybe that makes propositions not pictures after all.
Strictly speaking, we consider propositions and pictures without any identification of the things represented outside the propositions or pictures themselves. Whatever extraneous identification we may consider will not be in the proposition or in the picture itself.
Thus, propositions and pictures both can be true not only of what we choose to think of as being represented by them, but of other things as well as long as they fit the description. The painting of a twin will often be true of the other twin.
For the same reason, the same proposition or the same picture will be false of many things beside the one we may have in mind.
Thus, if we represent the same house twice in one picture, once blue, once gray, the two parts of the picture will be false of any red house, as indeed of mountains, people and neutrons.
The two parts of this picture may each be true of what we think of as the same house but at different times, once when it was blue, once when it was gray.
But if we think about finite conjuction of elementary propositions it seems possible to consider it to be a picture. So a solution would be those truth functions that are true only in one row in a truth table?
It is possible but rather limiting. Why not use disjunctions and negations? Or indeed implications? A truth table looks indeed somewhat like a kind of picture, although they are generally used to prove validity, not to present a picture of the factual truth.
Not very practical, but we could use a truth table, without any implication in it, to paint the picture of Mona Lisa. It would be a proposition. Aren't all forms of expression logically equivalent? I would hope so.