I’ve tried to write this post before https://andywootton.wordpress.com/2015/07/07/software-life-cycle-part-2-from-craftsmanship-to-computational-science/
but I just answered a question about ‘software engineering’ on LinkedIn and I’m pleased with the brevity:
Agile software development is the application of the scientific method to understanding the requirements for a software product. Each iteration is an experiment to confirm a hypothesis of what the customer should really have wanted at the beginning, if they’d known what they know now.
On The Outside 