Thresholds of Sustainability: Necessary and Sufficient Conditions for Green Buying Behavior

This study investigates the determinants of eco-buying behavior by drawing from the Theory of Planned Behavior (TPB) and considering green consumption values and prosocial attitudes. Using a cross-sectional survey of 436 adults in the UK and employing a two-step analysis with Partial Least Squares Structural Equation Modelling (PLS-SEM) and Necessary Condition Analysis (NCA), this research examines both sufficient and necessary conditions for sustainable purchasing behavior. The findings reveal that green consumption values and social influence are positively associated with green buying behavior, with green consumption values exerting the strongest influence. Conversely, prosocial attitudes and perceived behavioral control show no significant direct effects, yet age moderates the relationship between prosocial attitudes and green buying behavior. Moreover, NCA identifies green consumption values and perceived behavioral control as necessary conditions at specific thresholds, underscoring their importance in fostering high levels of green buying behavior. Additionally, a logarithmic relationship is observed between green consumption values and green buying behavior, suggesting diminishing returns at higher levels of green consumption values. Notably, the influence of green consumption values on green buying behavior is stronger among older individuals (35+), highlighting age-based differences in sustainable consumption. By integrating both sufficient and necessary conditions, this research addresses the attitude-behavior gap in sustainable consumption, offering novel insights into the roles of intrinsic values and social influences. These findings challenge established constructs like perceived behavioral control and highlight the relevance of advanced analytical methods in sustainable consumer research. The study contributes theoretical insights and practical implications for sustainable marketing strategies targeting value-driven consumers.