Bill Inmon vs. Ralph Kimball

Kimball -Let everybody build what they want when they want it, we'll integrate it all when and if we need              to.(BOTTOM-UP APPROACH).
            Pros: fast to build, quick ROI, nimble
           Cons: harder to maintain as an enterprise resource, often redundant, often difficult to
           integrate data marts.

Inmon - Don't do anything until you've designed everything.(TOP-DOWN APPROACH)
             Pros: easy to maitain, tightly integrated
             Cons: takes way too long to deliver first projects, rigid

                                    There is no right or wrong between these two ideas, as they represent different data warehousing philosophies. In reality, the data warehouse systems in most enterprises are closer to Ralph Kimball's idea. This is because most data warehouses started out as a departmental effort, and hence they originated as a data mart. Only when more data marts are built later do they evolve into a data warehouse.