On Trust Massimo Felici
Outline 1 What is Trust? Trust matters Trust problems Seeking an Experimental Trust Framework Trust and Dependability Directions for future work
What is Trust? 2 Constructive Trust Different Trust Features or Meanings Different meanings of trust Characterization of trust in terms of basic constructs: Trusting Intention, Trusting Behavior, Trusting Beliefs, System Trust, Dispositional Trust and Situational Decision to Trust Trust features, e.g.: Competence, Predictability, Benevolence and Integrity References: [5, 6, 7, 8]
What is Trust? 3 Relational Trust Trust is relational Trust as a three-part relation A Trusts B in to do X or in matters Y Trust depends on the context or situation Trust is subjective: trust (or, symmetrically, distrust) is a particular level of the subjective probability with which an agent assesses that another agent or group of agents will perform a particular action, both before he can monitor such action (or independently of his capacity ever to be able to monitor it) and in a context in which it affects his own action. References: [2]
What is Trust? 4 Trustworthiness In general, the complexity of the problem of trust derives primarily from the complexity of the problem of trustworthiness. [...] the motivations for being trustworthy are manifold. In a sense, trusting someone in some context is simply to be explained as merely the expectation that the person will most likely be trustworthy. Inducements: internal (e.g., moral rules, interests, consequences, etc.), external (e.g., social constraints, institutional constraints, norms, etc.) or mixed. References: [3]
What is Trust? 5 Rational Trust Rational theory of trust... Trust as a rational choice Encapsulated-interest model of Trust Your trust turns not directly on your own interests but rather on whether these are encapsulated in the interests of the trusted. You trust someone if you believe it will be in her interest to be trustworthy in the relevant way at the relevant time, and it will be in her interest because she wishes to maintain her relationship with you. References: [3]
What is Trust? 6 dual concept of trust like Trust, a three-part relationship A distrust B with respect to X like Trust, a matter of degree Distrust asymmetries between Trust and Distrust: asymmetric grounds (motivational and epistemological), asymmetric societal implications
Trust Matters 7 One-way Trust (iterated) Interactions Mutual Trust (e.g., Prisoner s Dilemma) Thick Relationships (e.g., social and institution relationships, group memberships, etc.)
Trust Matters 8 Interactions Increasing complexity of interaction Different mechanisms work/cope with different complexities Local trust relationships do not scale up
Trust Matters 9 Considerations on Interactions Thick relationships expose the limitations of games games poorly capture knowledge about thick relationships games capture cooperative interactions, rather than trust games need to be interpreted with respect to contextual relationships local relationships might be easy to capture/model/understand/formalise/...; on the other hand, some global phenomena may be little influenced by thick relationships Local and Global Trust
Trust Matters 10 Structures there is yet little understanding how emerging socio-technical structures (e.g., organizations, responsibilities, etc.) affect trust Other structural dependencies: Dependability, Risk perception Structure Complexity Diverse Structures: Formal structures, Social structures (e.g., Social Networks), Institutional structures (e.g., Responsibilities) Is there any implication from the social theory of risk? References: [1]
Trust Matters 11 A Formal Trust Structure A trust structure T is a triple T = (D,, ), where and are binary orderings on a set of values D. t s means that s represents a higher degree of trust than t information ordering or refinement: References: [4]
Trust Matters 12 Knowledge Uncertainty and Risk Trust involves knowledge uncertainty, hence, risk to acto on trust is to take a risk, although trust is not itself a matter of deliberately taking a risk because it is not a matter of making a choice. References: [3] This is, however, a simplistic interpretation of the relationships among trust, knowledge uncertainty and risk The better our understanding, the better the trust mechanisms that mitigate risk in presence of knowledge uncertainty Is there any implication for Risk Theory? Risky systems involve complex interactions, hence, do they require trust? References: [9]
Trust Problems 13 Modelling Interaction Games are a natural means for modelling interaction Three-part relation: A Trusts B in to do X or in matters Y Encapsulated-interest model of Trust Local and Global Interaction How to capture thick relationships (e.g., complex emerging relationships)?
Trust Problems 14 Measuring Trust Quantifying Trust Probabilistic view of trust (e.g., bayesian models of Trust) Events affect trust estimation An event structure is a triple ES = (E,, ) consisting of a set E of events which are partially ordered by, the necessity (or casuality) relation; the conflict relation is a binary, symmetric, irreflexive relation on events.
Seeking an Experimental Trust Framework Trust Relation and Interaction: A trusts B to do X, in matters Y or to discharge responsibility Z Encapsulated-trust model: encapsulating inducements Event Structures: ES = (E,, ), ordering on events; causality relationship Trust Structures: T = (D,, ); ordering degrees of trust; refinement on information Thick Relationships (e.g., social relationships, group memberships, etc.) 15
Seeking an Experimental Trust Framework Trust Relation and Interaction: A trusts B to do X, in matters Y or to discharge responsibility Z Encapsulated-trust model: encapsulating inducements Trust Structures: ordering degrees of trust; refinement on information Trust Events: ordering on events; causality relationship Trust Information Thick Relationships (e.g., social relationships, group memberships, etc.) 16
Dependability Aspects 17 Trust and Confidence Experts estimate their confidence (i.e., the probability that a claim is true ) on different claims The combinations of different arguments present some uncertainty and contingency for instance, despite the emergence of further knowledge strengthening one of the claims, the overall confidence on the claim could decrease Is it possible to analyse the (multi-leg argument) confidence problem as an interaction/game problem? Is it possible to interpret the confidence problem with respect to trust? This would tell us how trust/confidence differ.
Dependability Aspects 18 Trust and Responsibilities How does Trust extend Responsibility models? Relational Trust: A trusts B to discharge responsibility X Trust models involve many tree-part relationships over responsibilities How to extend emerging structures by thick relationships (e.g., social or institutional relationships)?
Dependability Aspects 19 Trust and Timing Event structures order and constrain occurring events Time bands define different focuses Trust might emerge over different time bands
Other Trust Aspects 20 Trust as process Trust as routine taken-for-granted Trust in Multi-Agent Systems Trust and Performance Organizational Trust Deciding when Trust is enough
Summary 21 Overview of Trust aspects and concepts (e.g., Distrust, Trustworthiness, etc.) Basic models: relational (e.g., three-part relation, thick relationships), encapsulated-interest model, interaction (games), trust structures and probabilistic trust (depending on events). How do the basic models relate to each other? Integrating them? Can we use/tailor them for structuring empirical analyses on Trust?
Directions for Future Work 22 Analysing/Modelling Trust in different application domains Developing Examples of Trust Problems Seeking an Experimental Approach to Trust: Requirements Developing an Experimental Approach to Trust: Experimental Analysis Modelling Framework, Looking at different Case Studies and Empirical investigations
23 References [1] Mary Douglas and Aaron Wildavsky. Risk and Culture: An Essay on the Selection of Technological and Environmental Dangers. University of California Press, 1982. [2] Diego Gambetta, editor. Trust: Making and Breaking Cooperative Relations. Basil Blackwell, 1998. [3] Russell Hardin, editor. Trust and Trustworthiness. Russell Sage Foundation, 2002. [4] Karl Krukow and Mogens Nielsen. Trust structures: Denotational and operational semantics. International Journal of Information Security, 6(2-3):153 181, 2007. [5] D. Harrison McKnight and Norman L. Chervany. The meanings of trust. Technical Report 96-04, University of Minnesota, Management Informations Systems Research Center (MISRC), 1996. [6] D. Harrison McKnight and Norman L. Chervany. What is trust? a conceptual analysis and an interdisciplinary model. In Proceedings of the Americas Conference on Information Systems, pages 827 833, 2000. [7] D. Harrison McKnight and Norman L. Chervany. Conceptualizing trust: A typology and e-commerce customer relationships model. In Proceedings of the 34th Hawaii Conference on System Sciences (HICSS-34), volume 7, page 7022. IEEE Computer Society, 2001. [8] D. Harrison McKnight and Norman L. Chervany. Trust and distrust definitions: One bite at a time. In R. Falcone, M. Singh, and Y.-H. Tan, editors, Proceedings of Trust in Cyber-societies, number 2246 in LNAI, pages 27 54. Springer-Verlag, 2001. [9] Charles Perrow. Normal Accidents: Living with High-Risk Technologies. Princeton University Press, 1999.