Eric Ries opens The Lean Startup by arguing that startups — which he defines broadly as any human institution designed to create new products or services under conditions of extreme uncertainty — require a fundamentally different management methodology than established, mature businesses operating in more predictable, well-understood market conditions.

Ries's foundational argument:

• He argues conventional management practices, developed primarily for optimizing execution within relatively well-understood, predictable business contexts, prove poorly suited to the genuine uncertainty startups typically face regarding whether their fundamental business model or product concept even represents something customers actually want
• Drawing on his own startup experience, including notable early failures before developing the methodology the book presents, Ries argues this genuine uncertainty requires a scientific, hypothesis-testing approach to business building, rather than extensive upfront planning based on assumptions that haven't yet been genuinely validated
• This foundational premise, drawing partly on lean manufacturing principles adapted to the startup context, sets up the book's overall project: presenting a systematic methodology for testing and validating fundamental business assumptions rapidly and efficiently, rather than assuming extensive upfront planning alone can adequately address genuine startup-stage uncertainty

This foundational framing establishes Ries's overall approach: treating startup building as a scientific, hypothesis-testing process requiring rapid, iterative validation of core business assumptions, rather than confident execution of an extensively pre-planned business strategy.