What are weak and strong chords?

Question

I'm reading Jazz Theory by Stuart Smith. In the chapter on functional harmony the author introduces the notion of strong and weak chords: > I, II, and IV are generally treated as **strong chords**. V, VI, and III are generally treated as **weak** (IIIm7 and VIm7 as representatives of the Tonic constitute a special case, which is discussed below.) As we shall see, VII has a context-dependent role in tonal music. Sometimes it is treated as a form of dominant, while at others it is used as part of a circle- of-fifths structure such as IV VII III. In either case it would be considered a weak chord in the sense used here. Please could you explain what does it mean - strong and weak chords, and what qualifies a chord as strong or weak? Is it somehow connected with stable and unstable degrees they are made up from?

Answer 1

I think that the use of the terms strong and weak chords are misleading. The difference between tonal and atonal music is the theory that in tonal music, there are tones and chords that hold more weight, than others, but in atonal music each tone is treated as equals.

I would say that there is a hierarchy in terms of importance. The tonic (I) and dominant (V) chords are the most important because without them we don't have a tonality. The sub-dominant (IV), supertonic (ii), mediant (iii), and sub-mediant (vi) are chords that lead to the dominant chord. The leading tone can be used used as a dominant replacement, but never used as a cadence.