Josh's StudyWiki

ClassificationSystems-PortersFiveForces

3 min read

Connection: Classification Systems ↔ Porter’s Five Forces

Before you can apply Porter’s Five Forces to an industry, you have to define the industry — and that definition is a classification problem. Where you draw the industry boundary determines which rivals, substitutes, and buyers count. Draw it too narrowly and you miss key threats. Draw it too broadly and the analysis becomes meaningless.

PHIL 252’s classification rules give you a principled way to think about whether an industry boundary is drawn well.

From PHIL 252 — Classification Systems

A good classification system must be:

  • Exhaustive — every item falls into some category
  • Mutually exclusive — no item belongs to two categories at once
  • Clear — the criteria for membership are unambiguous
  • Adequate — the categories are fine-grained enough to be useful

Classification errors lead to misplaced items. In logic, this produces invalid conclusions.

See ClassificationSystems for the full framework.

From ADMN 201 — Porter’s Five Forces

Step one of applying the five forces is industry definition: deciding what counts as a competitor, what counts as a substitute, where the supplier chain starts and ends, and who your buyers actually are.

Porter notes this explicitly: the practical application of the framework begins with “figuring out what your industry is.” Industry definition determines which forces apply and how strongly.

See PortersFiveForces for the full framework.

Why This Matters

When industry definitions are drawn poorly, the five forces analysis misfires:

Classification ErrorEffect on Five Forces Analysis
Too narrow (e.g., “only direct-mail advertising”)Misses digital substitutes; underestimates threat of substitutes
Too broad (e.g., “all entertainment”)Lumps together industries with completely different force profiles; analysis becomes useless
Ambiguous criteriaAnalysts disagree on whether a firm is a rival or a substitute; competitive threats get miscounted

Classic example — Airlines vs. High-Speed Rail: If you classify airlines and high-speed rail as competing in “long-haul travel,” the threat of substitutes for airlines goes up significantly. If you classify them as separate industries, it looks lower. Same reality, different classification, different strategy.

Classic example — Netflix: In 2007, Netflix classified its industry as “DVD rental.” By 2012 it was “streaming video.” By 2020 it was “attention” (competing with sleep, according to Reed Hastings). Each redefinition changes the entire force profile.

Why Understanding Both Together Deepens Each

  • A five forces analyst who doesn’t think about classification will draw industry boundaries carelessly — and get wrong answers from correct methodology.
  • A student of classification who only sees it as a logic tool misses how high-stakes the real-world version is: a misclassified industry boundary is a strategic error that costs real money.

Together: the logical rigour from PHIL 252 gives the strategic framework from ADMN 201 a sharper foundation.

ClassificationSystems, PortersFiveForces, BusinessEnvironments, DegreesOfCompetition

graph LR
    subgraph PHIL252["PHIL 252 — Classification Systems"]
        A[Good classification:\nexhaustive · exclusive\nclear · adequate]
        B[Classification error:\ntoo narrow / broad\nambiguous criteria]
    end

    subgraph ADMN201["ADMN 201 — Porter's Five Forces"]
        C[Step 1: Define\nyour industry]
        D[Apply five forces\nto that industry]
        E[Strategy: positioning\nin the industry]
    end

    A -->|"enables rigorous"| C
    B -->|"corrupts"| C
    C -->|"frames"| D
    D -->|"informs"| E

Graph View

Backlinks