The Naturalism of Tonality – Part 2: Exploitations

“Tonality is a natural force, like gravity„ – Paul Hindemith

The reason why there is Tonal Gravity is because of the dominant, but what are ways of exploiting it?, how do imperfect (half), plagal or interrupted (deceptive) cadences fit in with the concept of tonal gravity? Basically, they are there to create tension within the piece – to prolong the dominant – , and to fool the listener.
In reality, there are only three possible chords in tonal music, Tonic, Subdominant, and Dominant. To make music more interesting (as I, IV and V can get laboured after a while), there are variations in these chords. IV can also be iv, ii, or II (among a myriad of others), V and be vii○, iii7 (and countless others ), I can be VI, bVI, to name a few. With chord IV and V, the variants are often just that, variants to make music more interesting, however the latter (I) it more often attributed with attempting to fool the listener. When the listener gets pulled towards the Tonic (through a Dominant chord) and instead finds bIV it is (be it only slightly) a shock of sorts to have resolved to the tonic yet have the release taken away all the same.
You might ask how bIII fits within this system, and the answer is not black and white. The only way to determine a chords function is to assess its surroundings. Ambiguous situations may require educated guesses, but more often than not, one can come to an adequate decision. Backtracking slightly (Bear with me as I do digress into listing them) the tonic can be a number of chords: I, bIII, III, bVI, VI (Mention of their parallel minors is unimportant). It is because of these Chromatic third relations that (which all include at least two notes from chord I, minor or major) that a doorway is opened for various Dominants and Subdominants. For example, because of bIII’s relation to I, bVII (bIII’s dominant), can also be dominant of I. Because of this, many chord have two or three possible functions. III can be dominant as well as tonic; because of (any variant) VI’s proximity with chord IV it can be Subdominant as well as Tonic. To determine which of these a chord’s function actually is, one must analyse the chords surrounding it.

Examples A and B are quite straight Chromatic Mediant borrowing. But in example C, while both sets of progressions are logical, the rhythm of the allotted chords do not follow logical sense (using the lower interpretation) as it resolves before the tonic. In Example D, there is no logical functionality in the chords if following the bottom interpretation.

Part 1: Tonal Gravity
Part 3: Inherent Tonality