The page will support you in satisfying Writing Learning Objective:
REASONING - Develop ideas using effective reasoning and productive patterns of organization (claim-evidence-reasoning, cause-effect, compare-contrast, etc.).
You should be able to
Describe why engineers’ appeals should be logical (logos) and ethical (ethos).
Define the three parts of a logical appeal: claim, evidence, and warrant (reasoning).
Use logical appeals when analyzing and interpreting lab data.
Why Should You Care About Rhetorical Strategies When Writing Engineering Lab Reports?
Typically, the audience aims to learn a student’s thoughts through reading lab data analysis and interpretation results. They want to read your main ideas or how you apply technical meaning to the lab data. Therefore, lab report writers need to make their own points or claims based on the factual lab data as the primary source and supported by, or compared to, secondary sources (outside references).
Opinion versus Claim in Engineering Lab Reports
No personal opinions
The lab report audience is not interested in personal opinions about lab data. Opinions, which can be defined as views or judgments formed about something, are not necessarily based on “fact” or “knowledge,” so they are not appropriate for including in lab reports. The following sentences from lab reports are examples of opinions being used in lab reports: “This lab was unsuccessful.” “I think the lab data are reasonable.” “In my understanding, sample A is better than sample B.”
Make claims based on lab data and factual evidence
In contrast, claims can “convince” your points or deliverables to the lab report audience who may or may not agree. Claims are statements about what is true or about what should be done. Therefore, good claims provide the main argument of a lab report. A claim must be specific and convincible; therefore, the writers’ claims should be supported by evidence (lab data, existing theories, data/knowledge from outside sources, engineering principles, etc.), which the audience can trust. The following sentence from a lab report is an evidenced-based claim: “A 1045 steel sample is stronger than a 1020 steel sample because of its 20% higher yield strength and 15% higher ultimate tensile strength.
Out of the Three (Logical, Ethical, and Emotional) Appeals of Argument, Which One do Engineers Mostly Use in Reports?
Use Logical Appeals
Strong arguments have a balance of all three argumentative appeals: logical(logos), ethical(ethos), and emotional(pathos). However, engineers, typically, do not value emotional appeals because lab reports aim to deliver factual, credible, but impersonal technical information to the audience.
Claim-Evidence-Warrant: Three Parts of a Logical Appeal
An answer (or a finding) to the problem you defined or investigated. Your understanding (or main idea) to present to the audience.
Example: 1045 medium carbon steel is harder than 1008 low carbon steel at the room temperature.
Lab data used to support the claim.
Example: The lab data from Table 1 show the average hardness of 1008 steel coupons is 85 HRB while that of 1045 steel is 99 HRB.
Connecting your claim and the evidence logically using engineering principles. Often, secondary sources (other’s data, ideas, and scholarship) can be used for language and further support of the claim.
Example: Addition of carbon as an alloying element in ferrous alloys can create local nonuniformity in the lattice, which makes plastic deformation more difficult by impeding dislocation motion [reference to secondary source].
Show student’s feeling to strengthen the claims: “This lab is unsuccessful.” “I am glad the system works!” “Data make sense.” Note that engineers rarely use emotional appeals.
Make claims without relevant evidence.
Use of extreme (and subjective) adjectives to strengthen the claims: very, extremely, significantly, etc. Instead, use quantities to strengthen the claims (“the value was increased by 200%.” “the average decreased more than half.”).