Course 05 — Reasoning, Uncertainty, and Professional Judgment

Professional judgment connects evidence to a decision for which a person will answer. It requires more than a correct calculation or a confident recommendation.

You must understand the decision's purpose, governing requirements, uncertain inputs, and possible consequences. Other people must be able to examine your reasoning.

This course teaches a method for preparing and defending that reasoning. Technical competence remains essential. Use a competent specialist where the question exceeds your knowledge.

Series · Northbank case · Glossary · References

Prerequisites and outcomes

Complete Courses 01 to 04. Bring your controlled source index and requirements interpretation from those courses.

After this course, you can:

• Distinguish a claim from the evidence offered for it.
• Explain the limits of a model or observation.
• Compare options under stated uncertainty.
• Prepare a recommendation for the correct decision authority.
• Revise a conclusion when new evidence changes its grounds.

Use Northbank Packets A and B. Later packets are unavailable for this assignment.

Lesson 1 — State the claim and the intended reliance

Begin with the question that someone must decide. A broad question, such as “Is the equipment acceptable?”, conceals several decisions.

Technical suitability, expenditure approval, scope amendment, and permission to operate have different grounds. Identify the act that your recommendation supports.

A claim states that something is the case. Evidence can support or challenge that claim. A warrant explains why the evidence supports the proposed reliance.

A brochure might support a claim about a product family. It may provide no warrant for selecting a particular configuration.

An approved document can establish a project requirement. Its approval does not prove that the physical installation satisfies that requirement.

Prepare a short reasoning table:

Read the source passage with its status and conditions. Separate reported observation from your interpretation of it.

Use specific wording. “Observed at one connection” carries a different meaning from “available throughout the site”.

Do not fill a missing warrant with confidence, seniority, or repetition. Ask what evidence could expose the claim as wrong.

Lesson 2 — Examine models and observations

A model represents selected features of a situation. It can support a decision when those features include what matters for that decision.

The model may omit behavior that is unimportant for one question but decisive for another. State its purpose before examining its results.

Check the input identities, units, conditions, and source revisions. Then examine the relationships used to obtain the result.

Ask whether the model represents the relevant operating envelope. Examine abnormal conditions where their consequences matter to the assignment.

A precise result can remain unreliable when its inputs are uncertain. Additional decimal places do not improve those inputs.

Observations also have limits. Identify what was observed, where, under which conditions, and with which method.

Distinguish two forms of examination:

• Verification examines conformity to specified requirements.
• Validation examines fitness for intended use under the relevant conditions.

Checking arithmetic can support verification of a calculation. It does not establish that the calculation represents the intended service.

Use this examination sequence:

1. State the model's intended decision.
2. Check the input basis.
3. Examine the method and its limits.
4. Compare the result with an independent estimate or observation where appropriate.
5. Identify the conditions still unexamined.

An independent comparison must address the relevant failure. Two calculations using the same mistaken input can agree and remain wrong.

Lesson 3 — Treat uncertainty as part of the decision

An assumption is a proposition used while its truth remains unconfirmed. Permission to work on an assumption leaves it an assumption.

Identify uncertainty at the level where it affects the decision. “The design is uncertain” gives little help to the next participant.

“Available suction conditions are unresolved” identifies an input needed for pump selection. It also points toward investigation and an appropriate owner.

Assess each uncertain matter with four questions:

1. What could differ from the present assumption?
2. Which result depends on it?
3. What consequence could follow from being wrong?
4. What evidence or decision will resolve it?

Compare options under the same stated conditions. Include the option to investigate, defer the dependent act, or narrow its extent.

Do not assign probabilities without a defensible basis. A qualitative comparison can be more useful than invented numbers.

Sensitivity analysis examines how a result changes when an input changes. Use it to find inputs that deserve more attention.

For a quantitative analysis, state the tested range and its source. Distinguish a teaching assumption from a measured physical condition.

An unresolved matter need not stop all work. Identify the work it limits and the independent work that can continue.

Keep conditional recommendations precise. State the required condition, the person who establishes it, and the evidence needed before reliance.

Lesson 4 — Make the recommendation answerable

A recommendation should connect the decision question, options, evidence, uncertainty, and consequences. The reader must understand why you prefer the proposed course.

Explain the strongest reasonable alternative. This tests whether your preferred option survives a fair comparison.

Consider people affected beyond the decision meeting. Examine public and worker effects where the work can create them.

A favorable project outcome can still impose unacceptable consequences. Identify applicable obligations before balancing preferences about cost, time, or convenience.

Disclose a conflict of interest through the appropriate route. Separate your own incentive from the grounds offered for the decision.

Distinguish technical judgment from authority to make the final act. An engineer can recommend a scope change without having authority to approve it.

A sponsor can choose among project objectives and resource commitments. That choice does not establish the technical suitability of a configuration.

Use the appointment and applicable obligations to identify the decision owner. Ask for clarification when those sources leave a consequential authority unresolved.

Write the recommendation in this order:

1. State the requested decision.
2. Identify the applicable basis.
3. Compare the relevant options.
4. Explain the preferred option.
5. State its conditions and affected work.
6. Name the required authority.

Match the strength of the conclusion to the evidence. “Suitable for further review” and “suitable for procurement” support different acts.

State what would cause reconsideration. This makes the decision usable when the situation changes.

Keep a record only when another activity needs it. Preserve the decision's identity, grounds, conditions, and affected scope.

Lesson 5 — Invite challenge and repair the reasoning

Independent scrutiny can reveal omitted conditions, weak sources, and unreasonable comparisons. It works best when the reviewer knows the intended reliance.

Give the reviewer the decision question, source basis, calculation or argument, and proposed conclusion. Identify the limits of the requested review.

Ask for a challenge to the grounds. A review of formatting cannot establish technical adequacy.

Consider shared assumptions and interests that could impair scrutiny. A reviewer can miss the same defect as a producer. Challenge a consequential shared basis instead of relying only on agreement.

When someone challenges your reasoning, separate the observation from the proposed explanation. Check the actual source or result before choosing a repair.

Treat a finding through these actions:

1. Identify the affected claim.
2. Examine the supporting evidence.
3. Determine whether the conclusion changes.
4. Repair the affected work.
5. Re-examine the changed reasoning and dependent conclusions.

A changed conclusion can be evidence of improved judgment. Explain which premise changed and why the new conclusion follows.

Retain valid evidence where its basis remains applicable. Repeat examination when a change or unresolved concern warrants it.

Do not alter an acceptance condition merely to obtain a favorable result. A changed requirement needs its own substantive reason and authority.

Worked example — Northbank supplier decision

B01 requests acceptance within two working days. Its offered motors are rated for 480 V. A04 reports an existing connection at 600 V.

The project engineer frames the question as: “Can B01 support an authorized purchase package?” This identifies the intended reliance.

A04 supports a discrepancy finding. It does not establish spare capacity, protection coordination, or the suitability of any proposed supply arrangement.

B01 lacks a selected pump curve and declared operating cases. A02 also leaves important hydraulic inputs unresolved.

The engineer compares immediate acceptance with returning the submission for correction and substantiation. The evidence does not support immediate technical acceptance.

The engineer recommends a corrected, identified submission and the missing technical checks. Procurement continues commercial inquiries within its authority.

The engineer asks procurement to clarify the delivery-slot conditions. The two-day request does not establish that losing the slot will determine final delivery.

A05 remains a proposal for 22 litres per second. The technical review must preserve A02's approved 18 litres per second requirement.

The recommendation separates the supplier discrepancy, incomplete hydraulic basis, proposed scope change, and commercial uncertainty. Each requires its own response.

This conclusion does not decide which corrected pump or electrical arrangement will be suitable. Those decisions need further competent work.

Transfer example — Laboratory ventilation

A laboratory team has one airflow observation and a request to add another enclosure. The observation concerns the existing arrangement under one condition.

The team must establish the new operating conditions before relying on it for the addition. A precise reading cannot answer an unexamined design question.

Practice — Examine five claims

Use A01 to A06 and B01 to B03. Examine these statements as submitted claims:

• “The 600 V survey proves that no 480 V motor arrangement can be used.”
• “The supplier brochure proves that the offered pump meets Northbank's duty.”
• “Operations' request makes 22 litres per second the current requirement.”
• “Keeping Week 12 authorizes the supplier's technical deviation.”
• “All project work must stop until every open input is resolved.”

For each claim, identify its source basis, missing warrant, possible consequence, and a defensible replacement statement. Supply no invented technical or legal facts.

Prepare one review question that could change your replacement statement. Exchange your table with another participant.

Knowledge check

1. What distinguishes evidence from a warrant?
2. Why can two matching calculations remain unreliable?
3. What information makes an assumption usable for coordination?
4. How do verification and validation differ?
5. Which Northbank authority can amend the approved transfer-flow scope?
6. What should change when new evidence invalidates a decision premise?

Portfolio continuation and references

Keep the reviewed claim table and decision memorandum in your portfolio. Link them to the controlled sources from earlier courses.

Use them in Course 06 to explain a difficult recommendation. Use their unresolved inputs in Course 07 to define further work.

Source adaptation: Consolidated v8 §§1.3–1.6, 2.6–2.7, and 4.9–4.10. These sections address claims, uncertainty, examination, and preserved decision grounds.

Read the shared references for professional competencies and systems engineering fundamentals. Further reading is optional for the supplied exercise.

Assessed assignment — Defend a procurement recommendation

Prepare a decision memorandum using Packets A and B. Recommend the next response to B01's acceptance request.

Include a fair comparison of immediate acceptance, return for substantiation, and one other defensible response. Explain which work can continue.

State the evidence needed for the next technical decision. Separate the A05 proposal from the approved scope.

Explain which affected parties need consideration. Identify what remains unknown about consequences rather than inventing a Northbank hazard.

Defend the memorandum to a peer or mentor. Repair it where the challenge identifies an unsupported claim.

The instructor assesses these five observable criteria:

1. The memorandum identifies the requested act, source revisions, and intended reliance.
2. It preserves the approved scope and relevant authority boundaries.
3. It evaluates the voltage discrepancy and incomplete hydraulic basis without unsupported suitability claims.
4. It compares options, uncertainty, affected parties, consequences, and conditions for dependent work.
5. It explains the recommendation and records justified repairs after challenge.