Pretorius, Leon2025-02-112025-02-112025-052025-02*A2025http://hdl.handle.net/2263/100722Thesis (PhD (Engineering Management))--University of Pretoria, 2025.With Systems Engineering as the compass and Systems Thinking as the guide, this thesis navigates the labyrinth of the Circular Economy and Sustainability frameworks, seeking to unravel the mysteries of decision-making in a complex world. Each page turned is a step forward, a triumph, as you uncover the interconnected threads that weave together the fabric of our society. From the intricacies of sustainable systems to the nuances of human behaviour, this journey is a testament to the power of knowledge and the courage to pursue truth in an ever-changing world. In the evolving landscape of global economies, reshaped by information technology and digitisation, the relevance of sustainability has never been more pronounced. Amid growing environmental concerns and pressures for sustainability, the Circular Economy emerges as a viable alternative to the traditional Linear Economy, emphasising resource reduction and recirculation. However, decision-making within the Circular Economy is often complicated by the presence of cognitive biases among stakeholders, both internal and external. This thesis explores the intersection of Systems Engineering, Sociotechnical Systems and Circular Economy, aiming to develop a systematic framework that links cognitive biases to unsustainable activities. Through a comprehensive analysis that includes design science research methodology, this research identifies critical leverage points for leveraging biases and enhancing sustainable decision-making. By first conceptualising a few models for sustainable decision-making in the Circular Economy, the study provides development and evaluation measures to give valuable insights to practitioners and policymakers, facilitating the implementation of effective sustainability practices. The findings underscore the importance of understanding and addressing cognitive biases to advance the Circular Economy and promote a more sustainable and equitable global economy. This research contributes significantly to the field of Systems Engineering and sustainability by developing a novel framework that integrates cognitive biases into decision-making processes within the Circular Economy. By systematically analysing how cognitive biases influence stakeholder decisions, this study provides measurable insights into the barriers and facilitators of sustainable practices. The framework was validated through empirical testing, demonstrating improvement in stakeholder decision alignment with sustainability goals. This integration enhances the predictive accuracy of systems models and offers actionable strategies for practitioners to mitigate the negative impacts of biases, making this research a pivotal step toward more effective and sustainable decision-making in complex systems.en© 2023 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.UCTDSustainable Development Goals (SDGs)Systems engineeringSystems thinkingCircular economySustainability frameworksDecision-makingCognitive biasesThesisu20563991https://doi.org/10.25403/UPresearchdata.28382168