Minto opens by introducing the book's central organizing idea: effective business writing should present its main conclusion first, followed by the supporting arguments and evidence that justify it, rather than building up to the conclusion gradually as many writers instinctively do.

Why this top-down structure matters:

• Readers, particularly busy business readers, process information more easily when they know the main point upfront, allowing supporting details to be understood in context rather than as disconnected facts building toward an unclear destination
• Minto argues most writers instinctively structure their thinking chronologically (how they arrived at a conclusion) rather than logically (what the reader actually needs to understand the conclusion), producing confusing, hard-to-follow documents
• This top-down principle gives the book its title — a "pyramid" with the main conclusion at the top, supported by descending layers of grouped, logically related supporting arguments

This foundational principle sets up the specific structural techniques Minto develops in the rest of the book.