Weinberg's laws and rules are a collection of named heuristics, principles, and observations that gerald-weinberg articulated across his consulting books, beginning with secrets-of-consulting-1985 and continued in more-secrets-of-consulting-2001. They are practical wisdom distilled into memorable formulations — short enough to remember, specific enough to apply, and named so that practitioners can refer to them in conversation.
The Genre
The laws and rules belong to a genre of professional heuristics — patterns of organizational and human behavior given names so they can be recognized and discussed. Weinberg was deliberate about this genre choice. His consulting work had convinced him that practitioners needed handles for recurring dynamics, not formal theories. A consultant who can say "this looks like a Rudy Block situation" to a colleague has communicated a rich body of context efficiently. A consultant who must re-explain the dynamics from scratch each time is less effective.
The genre has antecedents in engineering (Murphy's Law, Goodhart's Law) and management writing (Parkinson's Law, the Peter Principle). Weinberg's contribution was to apply it systematically to software development and consulting practice, generating a large enough collection that the laws began to interact and reinforce each other.
Key Laws and Rules
law-of-raspberry-jam. "The wider you spread it, the thinner it gets." Consulting influence, management attention, and organizational communication all suffer from this constraint. Concentration produces results; diffusion produces noise.
rudy-block-rule (Rudy's Rutabaga Rule). People resist change regardless of whether their current situation is comfortable. The resistance is to change itself, not to the specific discomfort of the status quo. Named for a recurring character in Weinberg's consulting stories.
Prescott's Pickle Principle. "Cucumbers get more pickled than brine gets cucumbered." Small things entering large systems are changed by the system, not the other way around. A consultant entering a client organization is the cucumber; the organization is the brine.
The Orange Juice Test. A diagnostic probe: make a mildly unusual but reasonable request and observe how the organization responds. The response reveals the organization's flexibility, rigidity, and relationship to deviation from established norms.
The Fast-Food Fallacy. No difference plus no difference plus no difference eventually equals a clear difference. Small changes accumulate; the absence of visible immediate effect does not mean the absence of effect. Often used to explain why gradual cultural change is possible even when each individual intervention seems negligible.
The Rule of Three. If you cannot think of at least three different interpretations of what you received, you have not thought enough about what it might mean. A forcing function against premature closure on the first obvious interpretation.
The Ten Percent Promise. Never promise more than 10% improvement. Manages expectations, avoids setting up for failure, and keeps the consultant focused on incremental, sustainable gains.
The Tired Old Excuse. Organizations under pressure revert to familiar patterns of blame and avoidance. The "tired old excuse" is whatever the organization's characteristic deflection is — it's the tools, it's the schedule, it's the requirements. Naming the pattern makes it easier to interrupt.
The Weinberg Test. In secrets-of-consulting-1985, Weinberg offered various diagnostic tests for consultants to apply to their own practice — tests for whether you are actually helping, whether your presence is improving the client's capability or just solving this week's problem, whether you have become essential in a way that is bad for the client.
Relationship to Systems Thinking
The laws are not independent aphorisms but applications of general-systems-thinking principles to human and organizational systems. The Law of Raspberry Jam, for instance, is a statement about resource allocation in control systems. The Rudy Block Rule describes a feedback dynamic — the system's tendency to return to a prior state after perturbation. The Fast-Food Fallacy addresses the accumulation of small changes across time, a systems dynamics concern.
Weinberg consistently used memorable informal formulations to make systems thinking principles portable. A practitioner who does not know control theory can nonetheless apply the raspberry jam heuristic. The laws are systems thinking in everyday language.
Relationship to Consulting Practice
The laws emerged from Weinberg's direct consulting experience. Each names something he observed repeatedly across different clients and contexts. In secrets-of-consulting-1985 he framed them explicitly as the output of pattern recognition across many engagements — not theoretical constructs but empirical regularities.
more-secrets-of-consulting-2001 extended the collection, adding laws and rules developed in the decade and a half after the first book. The second volume also reflected the influence of Weinberg's work with virginia-satir and the satir-change-model — several of the later rules address the emotional and relational dimensions of consulting in more depth than the first volume.
The helpful-model-of-consulting is the organizing framework within which the individual laws make sense. Each law identifies a specific way that consulting can go wrong — influence diffused too thin, change resisted, small effects dismissed, excuses substituted for diagnosis. Together they map the failure modes of consulting, which is another way of mapping the conditions for consulting success.