An email excerpt (but one I didn't want to lose)

To my brother, or more generally, to anyone who has not yet met his first Darin:

My point in the previous email was to ask you for specificities.  Could you give me an example of a specific sentence, paragraph, passage, or piece of dialogue that suffers from a lack of nuance, i.e., that does not "mirror the inherent contradictions and ambivalence in [our thoughts]"?   This may be harder than you think.

"Darin got on the bus."

By most measures, this is is an innocuous, workmanlike sentence, with a single subject and object, and nothing else.  But it conceals a great deal.  For instance, the proper noun "Darin" brings up different images in different readers. To you, who are possibly yet to meet your first Darin, fictional (Darin isn't a very common a name in novels) or real, it is a placeholder for a person with no attributes. I hazard that the image in your head is one of a vaguely Caucasian man, perhaps long-nosed, a briefcase in his right hand, and wearing a tie.  For me, on the other hand, who knows two real people and one author named "Darin", a Darin-image is necessarily more amalgamated.  I see a man long of hair, flat of face, his stay-at-home t-shirt still stained with the cat droppings he tried to clean up in the afternoon.   We have already diverged in our interpretations of this sentence, and we haven't even gotten to the word "bus" (to which a similar hermeneutic treatment can be applied) yet.
All this may seem obvious to you.  In fact, you may claim that this is exactly the opposite of what you had in mind.  You may say: the shortest passages are the most ambiguous, and the longer a passage, and its accompanying description, the easier, and thus less rewarding, it is to imagine the object of the description.  But this is a specious argument.  A long passage is not inherently easier to place than a shorter one.  

"He wore ill-fitting clothes.  He had on a fake gold watch.  His lips wore a brownish hue, as though recently parted by a cigarette.  His face was mottled, it was obvious, by a recent accident.  He was missing his front teeth. Out of his pocket stuck a damp-deformed carton of Colgate Total.  His maroon gumboots were soaked through."

This, by any standards, is a bit of an itemization.  You may claim it belongs to the category of descriptions that leave little to the imagination.  But surely there is enough here to imagine!  As in the Darin example, each noun introduces shades of meaning, introduces images, that depend on the reader that apprehends them.  More importantly, the person being described here, unlike Darin, can be placed in a certain stratum of society---the man of few means---and this fact is itself enough to propel it beyond any accusations of dutiful thoroughness.   

Given, then, that there is always a great deal to imagine, that a passage always introduces more possibilities than it closes off, the question is not: Does a passage leave much or little to the imagination? but rather: What does this passage leave to the imagination? Different schools of fiction (I assume here that we're talking about fiction;  non-fiction is a whole other ballgame) answer this question in different ways.   The minimalists would stick to the Darin-like  sentences, which they seem to admire a great deal.  

"He looked very dead.  It was raining. I liked him as well as anyone I ever knew." (A Farewell to Arms, Ernest Hemingway)

The point of this kind of writing, apart from "the mere ratification of male taciturnity" it embodies, is to hint at a world just beneath the fictional surface, one pierced only at critical junctures by the fiction itself.   In theory, they leave a lot to the imagination. In practice, the amount to be imagined, if not managed properly, can overshadow the fiction, until everything comes to seem distended rather than pregnant with portent.  For this reason (and others, of course), minimalism is difficult to master, and only certain kinds of writers (not to mention readers) are suited for it.  

I myself prefer the opposite of minimalism:  

"They looked out, frowning into the sun, at what was left of a High Victorian garden, a wide round pond with a disused fountain of crumbling tritons, like angry, pock-marked babies, at its centre; the water had dropped to show the weed-covered pipe that fed it. The surrounding parterres had all been put to grass ten years before, when help had become a hopeless problem; though here and there a curved seat or a sundial or an unkillable old rose made a puzzled allusion to the plan it had once been part of." (The Spell, Alan Hollinghurst) 

In such writing, the writer is interested in parading the depth of his own imagination; in proving that he is better at imagining things than you are.   He too, leaves things to your imagination; but what he leaves is rather ordinary and can be deferred endlessly, until the end of the novel is met.  It is not an oversimplification to say that most novels can be located in a spectrum between minimalism and abundance.