Variability: Threat or Curse?

Ben Ale, D.N.D. Hartford, D.H. Slater

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

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In the philosophy of SAFETY-I variability is seen as a threat, because it brings with it the possibility of an unwanted outcome. Variability of hardware is curtailed by, amongst other things, precise specifications. Variability of human behavior is curtailed by inter alia regulations and protocols. In the philosophy of SAFETY-II variability is seen as an asset. In SAFETY-II, humans are seen as able to cope with the variability of technology circumstances to keep systems working. This capacity of coping has been designated resilience. Recently the meaning of resilience has been stretched to include the ability of restoring the operational state after an excursion into the realm of inoperability. The belief that humans will cope if an unexpected situation may arise, reduces the emphasis on preventive measures that limit the probability that the system may behave in an unsafe manner. The stretched meaning of resilience exacerbates this problem, because there is no real limit of what systems or society using these systems may bounce back from. The philosophies behind resilience engineering promote safety by exploiting the ingenuity of humans to keep systems within the desired operating envelope. Unfortunately the errors that may be introduced by over-relying on humans correctly assessing situations may also be fatal or catastrophic: maybe not for society as a whole, but surely for an individual, a group of individuals, or a company.
Original languageEnglish
Title of host publication29th European Safety and Reliability Conference
EditorsMichael Beer, Enrico Zio
Place of PublicationSingapore
PublisherResearch Publishing
Number of pages6
ISBN (Print)978-981-11-2724-3
Publication statusPublished - 2019
Event29th European Safety and Reliability Conference - Hannover, Germany
Duration: 22 Sep 201926 Sep 2019


Conference29th European Safety and Reliability Conference
Abbreviated titleESREL 2019
Internet address


  • Resilience Human Error
  • Variability

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