Adverse Selection is a market failure that occurs when information asymmetry causes the less desirable participants in a market to be more likely to engage in transactions, driving out the more desirable participants. First formally described by George Akerlof in his 1970 "Market for Lemons" paper (for which he received the Nobel Prize), it explains why used car markets, insurance markets, and hiring can systematically fail to function efficiently.
Cost-Benefit Analysis (CBA) is a systematic decision-making framework that quantifies all relevant costs and benefits of a course of action — including indirect and intangible ones — and compares them to determine net value. It disciplines decision-making by forcing explicit identification of trade-offs rather than allowing them to remain implicit. Widely used in public policy, investment appraisal, project selection, and operational decisions at all levels.
Fungibility is an economic principle stating that individual units of a commodity or resource are mutually interchangeable and identical in value. In the context of decision-making, it means that $1 is always $1, regardless of whether it was earned through labor, won in a lottery, or found on the street. Understanding Fungibility allows individuals to overcome the "Bucket Trap" of Mental Accounting, enabling more rational resource allocation, debt management, and investment strategies. It serves as the mathematical antidote to emotional labeling, ensuring that decisions are based on absolute net worth rather than the subjective "story" attached to a resource.
Incentive Theory describes how rewards, punishments, and structural conditions shape human behaviour by changing the costs and benefits of different actions. Central to economics, psychology, and organisational design, it explains why people respond to the incentives they actually face rather than those we intend, why misaligned incentives are the root cause of most persistent organisational dysfunction, and how to design systems that produce desired behaviour reliably.
The Law of Diminishing Returns states that as you add more of one input to a fixed set of other inputs, the marginal output from each additional unit eventually decreases. After a certain point, each extra unit of input produces less additional output than the previous unit. This fundamental economic principle governs hiring decisions, marketing spend, feature development, workout volume, and most resource allocation decisions.
Network effects occur when a product or service becomes more valuable as more people use it, creating self-reinforcing growth loops that can produce winner-take-all dynamics. Understanding the network effects mental model helps founders, investors, and strategists identify when a business can achieve exponential rather than linear growth, and when competitive advantages become structurally unassailable. Learning how to use network effects is essential for platform strategy, market entry decisions, and evaluating whether a business can sustain long-term defensibility.
Opportunity Cost is the value of the best alternative forgone when a decision is made. It is one of economics' most fundamental concepts and one of the most consistently ignored in practical decision-making. Every choice eliminates other choices; the opportunity cost is the best of those eliminated alternatives. Failing to account for opportunity cost leads to systematic overvaluation of existing commitments, undervaluation of alternatives, and poor allocation of time, money, and attention.
The Pareto Principle states that roughly 80% of effects come from 20% of causes. Originally observed by economist Vilfredo Pareto in 1896, who noted that 80% of Italy's land was owned by 20% of the population, the principle has since been documented across domains from business revenue (80% from 20% of customers) to software bugs (80% caused by 20% of code). As a decision-making tool, it directs attention and resources to the high-leverage minority of inputs rather than distributing effort uniformly.
The Principal-Agent Problem arises when one party (the agent) acts on behalf of another (the principal) but has different interests, information, and incentives. The principal can't perfectly observe the agent's actions or effort, creating opportunities for the agent to act in their own interest rather than the principal's. Central to economics, law, and management, it explains why managers may not act in shareholders' interests, why doctors may over-prescribe, and why employees may shirk.
Satisficing is a decision strategy developed by Nobel laureate Herbert Simon in 1956 that involves searching through available alternatives until one meets a pre-defined acceptability threshold — and then stopping, rather than continuing to search for the optimal choice. Simon coined the term by combining 'satisfying' and 'sufficing.' It reflects his observation that bounded rationality — the cognitive and informational limits on human decision-making — makes optimization impractical for most real-world decisions. Satisficing is not settling; it is the rational response to the cost of optimization.