── ── Mental model
Utilitarianism
Utilitarianism holds that the right action produces the greatest net well-being across all affected parties, weighted by magnitude and probability. Its power: it forces implicit trade-offs explicit. Its limit: the aggregation problem — summing welfare can justify severe losses to a few for diffuse gains to many, with no individual floor.
Run Utilitarianism on a real problem
Bring something you're actually deciding — free, in the browser.
How it works
Five steps producing a Utilitarian Welfare Map.
Stop rule: If impacts span qualitatively different dimensions (money vs. physical safety vs. autonomy), do not add them without an explicit conversion rate and its justification.
1. Map all affected parties. (a) primary beneficiaries; (b) primary cost-bearers; (c) indirect affected; (d) future/long-term. Omitting any group biases the analysis. 2. Estimate welfare impacts per party. Nature (economic/physical/psychological/opportunity), magnitude (significant/moderate/minor), probability. Quantify where possible; rank qualitatively where not. 3. Assess the aggregation problem. Are impacts commensurable? Name the aggregation assumption and its ethical weight before summing. 4. Compute or rank net welfare outcome. Identify the welfare-maximizing option and the option with best minimum welfare. 5. Stress-test the most contested assumption. If wrong by 2x, does the conclusion change? Name the assumption, sensitivity, and what would resolve it.
When to use it
- user asks 'what produces the most good,' 'who benefits and who gets hurt,' 'what's the net impact,' 'is this worth the trade-off,' 'what does the greatest good mean here'
- user needs to evaluate a policy, product, or organizational decision that affects multiple parties differently
- user is performing cost-benefit analysis or ethical trade-off evaluation
When not to use it
When the decision is routine and reversible, applying a formal method costs more than it returns.
Worked example
Cost-Benefit Analysis of the Clean Air Act (1970)
A primary-source-documented utilitarian welfare analysis. The US Environmental Protection Agency has conducted and published detailed cost-benefit analyses of the Clean Air Act since its passage, providing one of the most thoroughly documented public-policy utilitarian analyses available.
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