Abductive Reasoning
Painting with a broad brush, abductive reasoning1 occurs when we seize upon the simplest plausible explanation for (at least) the important observations. In effect, it works backwards from observation of consequences to explain them by way of the minimum possible number of degrees of freedom2. See also reasoning. Contrast with inductive reasoning and deductive reasoning. We... read more
Analysis
Analysis is the process of examining a thing by identifying its constituent parts and describing the relationships between them. Contrast with synthesis. As a verification method, analysis is the inference (by extrapolation, interpolation, logic, etc. using some algorithm) of the value(s) for some characteristic using validated models and engineering relationships. The method is applicable IFF... read more
Anecdotal Data
Data that are offered without objective substantiating evidence. In the case of the present document, often “what I recall being told as a young ‘un”. Lack of objective evidence doesn’t mean the data are wrong. It just means they cannot be accepted as definitive.
Belief
A state or habit of mind in which trust, confidence, or reliance is placed in some object of perception without regard to objective proof. Because objectivity is not a criterion, belief almost always entails a significant emotional investment. Contrast with knowledge.
Bias
Literally, a leaning toward (or away from) some specific orientation. In this context, “orientation” is should be interpreted as being relative to “truth”. Being biased is the opposite of being impartial, or neutral. The term originates with reference to fabric that is cut at some angle to the weave.
Causal Factor
A causal factor is an event or circumstance which, if removed from an antecedent chain of events or conditions, will alter the details of a result (e.g., magnitude or probability of occurrence) but not preclude its essential nature. The term is most often used in the context of Root Cause Analysis, where the “result” is... read more
Cognition
Simplistically1, the mental processes by which knowledge and understanding are gained. For our purposes, cognition can involve either reasoning 2, intuition3, or a bit of both. The concept of cognition roughly corresponds to military concepts of “Situational Awareness” and “Situational Understanding”. Along with affection4 and conation5, cognition is one of the three ways humans are... read more
Cognitive Bias
A departure from impartiality in cognition. This notion is distinct from concepts of error in morality or ethics. Being a bias, we’d expect to get approximately the same wrong answer every time a specific (cognitive) process is executed on the same set of inputs. Several types of cognitive bias have been identified, all of which... read more
Confirmation Bias
The (possibly unwitting) cognitive search for, filtering and interpretation of information that will support prior conclusions or belief. The reason that “independent verification” exists as a concept.
Deductive Reasoning
Deductive reasoning (sometimes referred to as “deduction”) occurs when two or more previously proven assertions are used to draw a demonstrably related conclusion1. In most cases, deduction is what we think of when we talk about Engineering processes that arrive at valid conclusions (e.g., sizing, derivation, and verification). In classical logic2 each assertion is usually... read more
Distal Cause
A distal cause that is an event or circumstance that is remote to the point or time of an event or condition, having precipitated other events or circumstances leading to the result. Contrast with proximate cause, root cause, and causal factor. For distal causes where the separation factor is time alone, see latent1. Causes (factors)... read more
Inductive Reasoning
As a crude simplification, inductive reason happens when the facts and data are “incomplete” with respect to the actual domain of the decision being made. In many cases, we create abstract rules and procedures based on “lessons learned”, then apply those generalizations to something else. Because there can be gaps1 in the train of logic,... read more
Knowledge
The facts, principles or other objects of perception gained through instruction, study, research or direct experience and (therefore) considered to be of unquestionable certainty. Knowledge, in this context, always results from an intellectual investment. It might (or might not) be cognitively entangled with an associated (possibly biasing) emotional investment. Contrast with belief, and compare to... read more
Latent (Failure, Defect, Cause)
A circumstance or condition present for some significant period of time before other events precipitate its consequence. The term is most often used in the context of Root Cause Analysis.
Mitigating Bias
In Engineering (and probably elsewhere), biases lead to outcomes of dubious quality. Their existence is a serious flaw in logic that can impact decisions and actions throughout the development process. They're difficult, if not impossible, to eliminate, but we can at least mitigate their consequence if we make a point of looking for them. That perspective supplies an underlying motivation for many System Engineering practices. read more.
Procedure
A defined sequence of circumstances, actions, reactions, status, feedback and expected outcomes which, when implemented by or on behalf of one or more operators, achieve some technical objective. Contrast with process and algorithm, which are more typically reserved for the context of software.
Prospective Deduction
In many cases of deduction, the premeses have prior, independent acceptance of validity. System Engineering (SE) practices accept unvalidated1 assertions as premeses, provided that they are subsequently subjected to formal validation as part of the development process. In the context of requirement derivation, dealing with validation of the premeses is an important part of traceability to... read more
Proximate Cause
A proximate cause is an event or circumstance immediately adjacent to a result. Contrast with root cause, causal factor, and distal cause.
Reasoning
The act of assembling or recounting a sequence or network of facts and data1 leading to an inescapable, definitive conclusion. Ostensibly, Engineers like us “reason” our way through problems to create designs. In this context, of course, “reason” implies a certain amount of logic in our thinking, which guides what data we pay attention to... read more
Root Cause
A root cause is an event or circumstance which, independent of all others, is sufficient to precipitate some specific result. The term is most often used in the context of Root Cause Analysis, where the “result” is a failure under investigation. Contrast with causal factor, proximate cause, and distal cause.
Science
Knowledge obtained and tested by way of the Scientific Method.
Scientific Method (Engineer’s version)
An algorithm comprised of the following steps: Observe phenomenon. Formulate hypothesis. Test hypothesis. Refine hypothesis based on results. Repeat until one or more of the following stopping criteria are met (in order of priority): The results are within the utility specified by the funding application in consideration of reasonable future use1; The results are within... read more
Why System Engineering?
System Engineering is frequently defended as a cost reduction method. Here, it is argued that regarding it as a collection of practices for mitigation of cognitive biases is a simpler rationale, eliminating the need for problematic substantiation. read more.