What is swing anyway?

From a subjective point of view, it is a feeling of forward propulsion combined with a sense of easy relaxation. The beat has to be posed between those two feelings.

From the point of view of the music itself, it has two main elements, the relative equality of quarter note beats and the phrasing of 8th notes.

(1) The jazz beat is one two three four, not: ONE two THREE four. It's almost one TWO three FOUR. Think of a walking bass with four more or less equal beats. Now think of the high hat clicking on two and four.

(2) The basic 8th note subdivision is swung rather than played straight. (This would be written out as an 8th note triplet with a rest between the two notes.) This is known as a "shuffle." Early rock and roll is still played in a shuffle rhythm; it's still basically a form of "swing" music.

Complications: (1) was an achievement of big bands in the 1930s. You will find a much more prominent up-and-down "two" feel in earlier jazz styles, like stride piano. Do these styles swing? They probably do. Sometimes too straight a "four" can get flat and colorless, like "one one one one one one one...." So maybe the lilt of the two feel is still an element of swing?

According to Gunther Schuller, that equality of the four beats comes from African music. Yet it emerged in jazz at a particular point in time. This raises the question of where this principle was hibernating between its African origins and its emergence in the Count Basie orchestra in the 1930s.

What if (1) and (2) are present but that tension between forward movement and relaxed ease is not perceived by the listener? The music doesn't swing but there might be differences of opinion. Crouch thinks Wynton can swing and Scott LaFaro can't. I hold the opposite opinion. I don't find swing in John Lewis or Nina Simone.

Of course music might not necessarily swing in the jazz sense but still be rhythmically engaging in an analogous way.