The chapter discusses the superiority of interaction over rule-based algorithms in computer problem-solving, challenging the prevailing view that all computing can be expressed as algorithms. It highlights the shift from mainframes to workstations and networks, from number-crunching to embedded systems and graphical user interfaces, and from procedure-oriented to object-based and distributed programming. The concept of interaction is likened to "marriage contracts" that adapt and learn over time, contrasting with the "sales contracts" of algorithms. The chapter also explores the limitations of Turing machines, which are closed systems that cannot handle external inputs or time, and introduces the idea of "interaction machines" that can model complex behaviors and environments. It emphasizes the importance of interfaces in specifying the behavior of interactive systems and the role of partial specification in system design. The chapter concludes by drawing parallels between the shift from rationalism to empiricism in philosophy and the transition from algorithmic to interactive models in computing, highlighting the practical and theoretical benefits of interaction in solving complex problems.The chapter discusses the superiority of interaction over rule-based algorithms in computer problem-solving, challenging the prevailing view that all computing can be expressed as algorithms. It highlights the shift from mainframes to workstations and networks, from number-crunching to embedded systems and graphical user interfaces, and from procedure-oriented to object-based and distributed programming. The concept of interaction is likened to "marriage contracts" that adapt and learn over time, contrasting with the "sales contracts" of algorithms. The chapter also explores the limitations of Turing machines, which are closed systems that cannot handle external inputs or time, and introduces the idea of "interaction machines" that can model complex behaviors and environments. It emphasizes the importance of interfaces in specifying the behavior of interactive systems and the role of partial specification in system design. The chapter concludes by drawing parallels between the shift from rationalism to empiricism in philosophy and the transition from algorithmic to interactive models in computing, highlighting the practical and theoretical benefits of interaction in solving complex problems.