The financial decision-making paradigm was developed in the 19^th century by the “marginal” school of economics and refined into modern financial tools by the 1950’s.  In essence, it says that by comparing incremental benefits with incremental costs, that rational decisions can and should be made.  While academic economists refined the exact conditions under which this is logically true, practical business professionals have simply just adopted these tools.  Business students learned to choose the greatest net benefits.  Some also learned to calculate the risk-adjusted, interest-rate discounted incremental after-tax cash flows.

In practice, finance professionals and business decision-makers have seen limitations in the theory, but adapted it to make “rational” decisions.  If qualitative factors exist, they are ignored, translated into numbers or considered separately.  If key numbers are unknown, they are estimated, modeled or limited.  If factors are interrelated, a simulation model is run or lesser factors omitted.  Cash flows 30 years out are ignored due to their low present value.  Rules of thumb are used as simple linear relations.  The whole is defined as the sum of the parts.  The principle of diminishing marginal returns is used to eliminate inconvenient, minor or detailed items.

For short-term or long-term decisions, the standard financial decision making tools are adapted to meet most situations.  With experience and business judgment, decisions are made with a high degree of confidence using this single approach.

In addition to the common “adjustments” accepted by financial analysts in practice, there are deeper criticisms regarding the financial paradigm.  It is inconsistent with the historical, accrual cost approach required in public accounting.  Managers are unable to estimate factors, so they are constructed by analysts.  For major investments or decisions, the inherently qualitative factors may be most important.  Fully-loaded costs are used throughout most financial systems, so decisions are guided by “the numbers”. Purely financial incentive systems lead to padding, managed numbers and missed opportunities.   Focusing on financial results alone leads to neglect of the asset, operations and customer levels of the balanced scorecard.  Accounting systems are not structured to monitor key decisions, but to eventually report historical costs.  The financial decision making paradigm does not directly help managers to solve problems or serve customers, but it can create an adversarial relation between line managers and the financial staff.

The 1980’s “quality revolution” lead to a time when there was significant support for a variation on Shakespeare’s maxim: “first, let’s kill all of the accountants”.   Since then, finance and accounting professionals have fine-tuned their models, linked to the balanced scorecard framework, enhanced allocations through activity based costing, simplified ROI models, learned quality paradigms and deliver a mixed dashboard of financial and operations measures.

 The financial decision-making paradigm remains at the core of modern business decision-making because it does a good job of organizing the key factors, determining the level of detail needed to make good decisions and communicating those decisions to others in a consistent fashion.  No paradigm is perfect, but the marginal cost-benefit approach is doing very well moving through its second century.