I do not want to claim that the two senses of ‘show’ that seem to me important are without overlap. Perhaps they represent two ends of a spectrum in which there are middle points of various kinds. I also think that more often than not poems/poets use both kinds of showing in the space of a single poem.
Show1 we might also call implication or letting the reader work it out. It is what the standard workshop manuals typically concentrate on in prose too – don’t tell the reader ‘He was short-tempered’ but show the character flying off the handle. There are a whole host of reasons why writing has more impact in this way (for example forcing writers to concentrate on the concrete) but perhaps the most important is creating the imaginative space for the reader to come to her own point of view. Showing1 is against closure, and in favour of the reader engaging actively with the text to create meaning.
Show2 is different – and perhaps under-recognised. It is the way the very structure of a poem leads the reader to a particular – changed – appreciation. Showing2 also asks the reader to engage in the activity of creating the work – but showing2 is, at least in part, a technique of closure which works across a broad segment of the writing (often over a whole poem – and perhaps over a whole novel). Here are two things you could use as comparisons that might help explain what I am after.
The first is the concept of a ‘Gestalt’ – used by a school of psychologists to conceptualise the way in which we (and other beings) grasp whole patterns of perception. A very simple example – :: is rapidly seen by anyone with a western education as 4. With larger numbers (for example twelve arranged as two groups of six like dice spots) the feat is more impressive. Acculturation is a vital part of this experience, people without a western education don’t grasp dice-pattern numbers as quickly as those who have that cultural experience, although they are often better at giving a count of a randomly displayed dot pattern. There is no such thing as uninterpreted experience and we experience the world through a vast range of overlapping patterns. We can clearly add new patterns and perceptions to our repertoire. So one way to think about showing2 is that the poem teaches us a new gestalt – a new organisation of thought, feeling and language (or language-feeling-thought).
A second way of thinking about showing2 is to go back to Blackmur’s ‘Expresses the matter at hand’ but with a Wittgensteinian tilt. ‘Express’ suggests that there was something inside which we’ve squeezed out into the open. Anyone suckled on the Philosophical Investigations will sense that is fishy. However, if we accept ‘express’ without the metaphysical presumption of something pre-existing which is expressed then that is what I mean by show 2. The poem ‘expresses’ the matter by creating the new expression (Gestalt) that organises our thought/perception/language. In this it also fulfils Blackmurs requirement that it ‘increases the available stock of reality’ – something new is brought into being which enriches our possibilities of perception. [Anti-realists would presumably cross out the ‘available’ and I’m tempted to side with them.]
The reason the poem has to show2 the matter it expresses is, of course, that as an original gestalt it cannot rely on the pre-existing stock of linguistic convention. A poem shows something that cannot be said (because if it can be said then why not use prose which is clearer!). Of course there is a risk in this view that we become too priestly and exclusive in or view of what ‘real poetry’ is, but also I think we have to be clear that there is no absolutely certain principle for the individuation of Gestalts (yep, that’s an English not a German plural!) – there can be as many as there are poems, not every poem shatters the world, most just give it a quiet nudge.