Agile and stage gates

Check out Agile and stage gates by John Goodpasture. Here is an excerpt:

One of my Agile Project Management students asked me about stage gates and agile.
My first response was this:

Agile is not a gated methodology, primarily because scope is viewed as emergent, and thus the idea of pre-determined gate criteria is inconsistent with progressive elaboration and…

The full article is available here.