Trust Theory

Cristiano Castelfranchi is full professor of Cognitive Sciences at the University of Siena, Italy, and Director of the Institute of the Cognitive Sciences and Technologies (ISTC) of the Italian National Research Council (CNR). Cristiano has a background in linguistics and psychology, and is active in the Multi-Agent Systems, Social Simulation, and Cognitive Science communities. He was program chair of AAMAS 2002, and is chair of several international workshops. He has published 11 books (3 in English), and more than 150 conference and journal articles.Rino Falcone is Leader Researcher for the T3 (Trust Theory and Technology) group at the Institute of the Cognitive Sciences and Technologies (ISTC) of the Italian National Research Council (CNR). His scientific interests include Natural Language Processing, Plan Recognition, Multi-agent Systems and Agent Theory.  Rino has published more than 100 conference and journal articles, organized several international conferences, and edited several special issues of international journal on these topics.

"I highly recommend this book to anyone who wants to delve deep into the concept of trust, in particular for use in computational applications and social simulations to strengthen awareness of complexity, complications and conundrums of trust." (JASSS, 2011) "Castelfranchi and Falcone's (both Italian National Research Council) is the first book providing an overview of the field of modeling trust and computational models of trust." (Book News, September 2010)

• Foreword xvIntroduction 11 Definitions of Trust: From Conceptual Components to the General Core 71.1 A Content Analysis 81.2 Missed Components and Obscure Links 121.3 Intentional Action and Lack of Controllability: Relying on What is Beyond Our Power 151.4 Two Intertwined Notions of Trust: Trust as Attitude vs. Trust as Act 171.5 A Critique of Some Significant Definitions of Trust 191.5.1 Gambetta: Is Trust Only About Predictability? 191.5.2 Mayer, Davis, & Schoorman: Is Trust Only Willingness, for Any Kind of Vulnerability? 191.5.3 McKnight: The Black Boxes of Trust 211.5.4 Marsh: Is a Mere Expectation Enough for Modeling Trust? 211.5.5 Yamagishi: Mixing up the Act of Trusting and the Act of Cooperating 221.5.6 Trust as Based on Reciprocity 261.5.7 Hardin: Trust as Encapsulated Interest 261.5.8 Rousseau: What Kind of Intention is ‘Trust’? 30References 312 Socio-Cognitive Model of Trust: Basic Ingredients 352.1 A Five-Part Relation and a Layered Model 362.1.1 A Layered Notion 362.1.2 Goal State and Side Effects 382.2 Trust as Mental Attitude: a Belief-Based and Goal-Based Model 382.2.1 Trust as Positive Evaluation 392.2.2 The ‘Motivational’ Side of Trust 442.2.3 The Crucial Notion of ‘Goal’ 452.2.4 Trust Versus Trustworthiness 472.2.5 Two Main Components: Competence Versus Predictability 472.2.6 Trustworthiness (and trust) as Multidimensional Evaluative Profiles 492.2.7 The Inherently Attributional Nature of Trust 502.2.8 Trust, Positive Evaluation and Positive Expectation 522.3 Expectations: Their Nature and Cognitive Anatomy 542.3.1 Epistemic Goals and Activity 542.3.2 Content Goals 552.3.3 The Quantitative Aspects of Mental Attitudes 562.3.4 The Implicit Counterpart of Expectations 582.3.5 Emotional Response to Expectation is Specific: the Strength of Disappointment 582.3.6 Trust is not Reducible to a Positive Expectation 602.4 ‘No Danger’: Negative or Passive or Defensive Trust 602.5 Weakening the Belief-Base: Implicit Beliefs, Acceptances, and Trust by-Default 622.6 From Disposition to Action 642.6.1 Trust That and Trust in 662.6.2 Trust Pre-disposition and Disposition: From Potential to Actual Trust 672.6.3 The Decision and Act of Trust Implies the Decision to Rely on 692.7 Can we Decide to Trust? 722.8 Risk, Investment and Bet 732.8.1 ‘Risk’ Definition and Ontology 742.8.2 What Kinds of Taken Risks Characterize Trust Decisions? 762.9 Trust and Delegation 772.9.1 Trust in Different Forms of Delegation 792.9.2 Trust in Open Delegation Versus Trust in Closed Delegation 802.10 The Other Parts of the Relation: the Delegated Task and the Context 822.10.1 Why Does X Trust Y? 822.10.2 The Role of the Context/Environment in Trust 832.11 Genuine Social Trust: Trust and Adoption 842.11.1 Concern 882.11.2 How Expectations Generate (Entitled) Prescriptions: Towards ‘Betrayal’ 882.11.3 Super-Trust or Tutorial Trust 892.12 Resuming the Model 91References 923 Socio-Cognitive Model of Trust: Quantitative Aspects 953.1 Degrees of Trust: a Principled Quantification of Trust 953.2 Relationships between Trust in Beliefs and Trust in Action and Delegation 973.3 A Belief-Based Degree of Trust 983.4 To Trust or Not to Trust: Degrees of Trust and Decision to Trust 1013.5 Positive Trust is not Enough: a Variable Threshold for Risk Acceptance/Avoidance 1073.6 Generalizing the Trust Decision to a Set of Agents 1113.7 When Trust is Too Few or Too Much 1123.7.1 Rational Trust 1123.7.2 Over-Confidence and Over-Diffidence 1123.8 Conclusions 114References 1154 The Negative Side: Lack of Trust, Implicit Trust, Mistrust, Doubts and Diffidence 1174.1 From Lack of Trust to Diffidence: Not Simply a Matter of Degree 1174.1.1 Mistrust as a Negative Evaluation 1184.2 Lack of Trust 1194.3 The Complete Picture 1204.4 In Sum 1214.5 Trust and Fear 1224.6 Implicit and by Default Forms of Trust 1224.6.1 Social by-Default Trust 1244.7 Insufficient Trust 1254.8 Trust on Credit: The Game of Ignorance 1264.8.1 Control and Uncertainty 1264.8.2 Conditional Trust 1274.8.3 To Give or Not to Give Credit 1274.8.4 Distrust as Not Giving Credit 129References 1315 The Affective and Intuitive Forms of Trust: The Confidence We Inspire 1335.1 Two Forms of ‘Evaluation’ 1345.2 The Dual Nature of Valence: Cognitive Evaluations Versus Intuitive Appraisal 1345.3 Evaluations 1355.3.1 Evaluations and Emotions 1365.4 Appraisal 1375.5 Relationships Between Appraisal and Evaluation 1385.6 Trust as Feeling 1405.7 Trust Disposition as an Emotion and Trust Action as an Impulse 1415.8 Basing Trust on the Emotions of the Other 1425.9 The Possible Affective Base of ‘Generalized Trust’ and ‘Trust Atmosphere’ 1435.10 Layers and Paths 1435.11 Conclusions About Trust and Emotions 144References 1456 Dynamics of Trust 1476.1 Mental Ingredients in Trust Dynamics 1486.2 Experience as an Interpretation Process: Causal Attribution for Trust 1506.3 Changing the Trustee’s Trustworthiness 1546.3.1 The Case of Weak Delegation 1546.3.2 The Case of Strong Delegation 1586.3.3 Anticipated Effects: A Planned Dynamics 1616.4 The Dynamics of Reciprocal Trust and Distrust 1646.5 The Diffusion of Trust: Authority, Example, Contagion, Web of Trust 1686.5.1 Since Z Trusts Y, Also X Trusts Y 1686.5.2 Since X Trusts Y, (by Analogy) Z Trusts W 1736.5.3 Calculated Influence 1736.6 Trust Through Transfer and Generalization 1746.6.1 Classes of Tasks and Classes of Agents 1756.6.2 Matching Agents’ Features and Tasks’ Properties 1756.6.3 Formal Analysis 1776.6.4 Generalizing to Different Tasks and Agents 1786.6.5 Classes of Agents and Tasks 1826.7 The Relativity of Trust: Reasons for Trust Crisis 1846.8 Concluding Remarks 188References 1897 Trust, Control and Autonomy: A Dialectic Relationship 1917.1 Trust and Control: A Complex Relationship 1917.1.1 To Trust or to Control? Two Opposite Notions 1927.1.2 What Control is 1927.1.3 Control Replaces Trust and Trust Makes Control Superflous? 1957.1.4 Trust Notions: Strict (Antagonist of Control) and Broad (Including Control) 1967.1.5 Relying on Control and Bonds Requires Additional Trust: Three Party Trust 1987.1.6 How Control Increases and Complements Trust 2007.1.7 Two Kinds of Control 2017.1.8 Filling the Gap between Doing/Action and Achieving/Results 2037.1.9 The Dynamics 2047.1.10 Control Kills Trust 2057.1.11 Resuming the Relationships between Trust and Control 2067.2 Adjusting Autonomy and Delegation on the Basis of Trust in Y 2067.2.1 The Notion of Autonomy in Collaboration 2097.2.2 Delegation/Adoption Theory 2097.2.3 The Adjustment of Delegation/Adoption 2137.2.4 Channels for the Bilateral Adjustments 2227.2.5 Protocols for Control Adjustments 2237.2.6 From Delegation Adjustment to Autonomy Adjustment 2257.2.7 Adjusting Meta-Autonomy and Realization-Autonomy of the Trustee 2257.2.8 Adjusting Autonomy by Modyfing Control 2267.2.9 When to Adjust the Autonomy of the Agents 2277.3 Conclusions 230References 2328 The Economic Reductionism and Trust (Ir)rationality 2358.1 Irrational Basis for Trust? 2368.1.1 Is Trust a Belief in the Other’s Irrationality? 2368.2 Is Trust an ‘Optimistic’ and Irrational Attitude and Decision? 2398.2.1 The Rose-Tinted Glasses of Trust 2398.2.2 Risk Perception 2468.3 Is Trust Just the Subjective Probability of the Favorable Event? 2478.3.1 Is Trust Only about Predictability? A Very Bad Service but a Sure One 2478.3.2 Probability Collapses Trust ‘that’ and ‘in’ 2488.3.3 Probability Collapses Internal and External (Attributions of) Trust 2488.3.4 Probability Misses the Active View of Trust 2508.3.5 Probability or Plausibility? 2508.3.6 Probability Reduction Exposes to Eliminative Behavior: Against Williamson 2508.3.7 Probability Mixes up Various Kinds of Beliefs, Evaluations, Expectations about the Trustee and Their Mind 2528.4 Trust in Game Theory: from Opportunism to Reciprocity 2548.4.1 Limiting Trust to the Danger of Opportunistic Behavior 2558.4.2 ‘To Trust’ is not ‘to Cooperate’ 2558.5 Trust Game: A Procuste’s Bed for Trust Theory 2568.6 Does Trust Presuppose Reciprocity? 2588.7 The Varieties of Trust Responsiveness 2608.8 Trusting as Signaling 2608.9 Concluding Remarks 261References 2619 The Glue of Society 2659.1 Why Trust is the ‘Glue of Society’ 2659.2 Trust and Social Order 2669.2.1 Trust Routinization 2689.3 How the Action of Trust Acquires the Social Function of Creating Trust 2689.4 From Micro to Macro: a Web of Trust 2709.4.1 Local Repercussions 2709.4.2 Trans-Local Repercussions 2719.5 Trust and Contracts 2729.5.1 Do Contracts Replace Trust? 2729.5.2 Increasing Trust: from Intentions to Contracts 2729.5.3 Negotiation and Pacts: Trust as Premise and Consequence 2759.6 Is Trust Based on Norms? 2759.6.1 Does Trust Create Trust and does There Exist a Norm of Reciprocating Trust? 2779.7 Trust: The Catalyst of Institutions 2789.7.1 The Radical Trust Crisis: Institutional Deconstruction 279References 27910 On the Trustee’s Side: Trust As Relational Capital 28110.1 Trust and Relational Capital 28210.2 Cognitive Model of Being Trusted 28410.2.1 Objective and Subjective Dependence 28510.2.2 Dependence and Negotiation Power 28910.2.3 Trust Role in Dependence Networks 29210.3 Dynamics of Relational Capital 29710.3.1 Increasing, Decreasing and Transferring 29710.3.2 Strategic Behavior of the Trustee 30010.4 From Trust Relational Capital to Reputational Capital 30110.5 Conclusions 302References 30211 A Fuzzy Implementation for the Socio-Cognitive Approach to Trust 30511.1 Using a Fuzzy Approach 30611.2 Scenarios 30611.3 Belief Sources 30711.4 Building Belief Sources 30711.4.1 A Note on Self-Trust 30911.5 Implementation with Nested FCMs 31011.6 Converging and Diverging Belief Sources 31111.7 Homogeneous and Heterogeneous Sources 31211.8 Modeling Beliefs and Sources 31211.9 Overview of the Implementation 31311.9.1 A Note on Fuzzy Values 31511.10 Description of the Model 31611.11 Running the Model 31611.12 Experimental Setting 31711.12.1 Routine Visit Scenario 31711.12.2 Emergency Visit Scenario 31911.12.3 Trustfulness and Decision 32011.12.4 Experimental Discussion 32111.12.5 Evaluating the Behavior of the FCMs 32211.12.6 Personality Factors 32211.13 Learning Mechanisms 32311.13.1 Implicit Revision 32411.13.2 Explicit Revision 32411.13.3 A Taxonomy of Possible Revisions 32511.14 Contract Nets for Evaluating Agent Trustworthiness 32611.14.1 Experimental Setting 32611.14.2 Delegation Strategies 32711.14.3 The Contract Net Structure 32811.14.4 Performing a Task 32911.14.5 FCMs for Trust 32911.14.6 Experiments Description 33011.14.7 Using Partial Knowledge: the Strength of a Cognitive Analysis 33311.14.8 Results Discussion 33911.14.9 Comparison with Other Existing Models and Conclusions 341References 34212 Trust and Technology 34312.1 Main Difference Between Security and Trust 34412.2 Trust Models and Technology 34512.2.1 Logical Approaches 34612.2.2 Computational Approach 34712.2.3 Different Kinds of Sources 34712.2.4 Centralized Reputation Mechanisms 34812.2.5 Decentralized Reputation Mechanisms 34912.2.6 Different Kinds of Metrics 35012.2.7 Other Models and Approaches to Trust in the Computational Framework 35112.3 Concluding Remarks 354References 35413 Concluding Remarks and Pointers 35913.1 Against Reductionism 35913.2 Neuro-Trust and the Need for a Theoretical Model 36013.3 Trust, Institutions, Politics (Some Pills of Reflection) 36113.3.1 For Italy (All’Italia) 362References 363Index 365