Substantiated vs. Vague Circular Economy Claims in Fashion Brands: Claim Support Credibility, Authenticity, and Trust in Greece vs. the UK

Circular economy (CE) claims in fashion aim to mobilize consumer participation in reuse and recycling, yet the interpretative flexibility of “circular” language can also enable vague messaging and skepticism. This study investigates how consumers assess CE fashion claims in terms of (a) claim substantiation quality (CSQ) and (b) claim support credibility (CSC), and how these assessments influence perceived green authenticity (PGA), green trust (GTR), and circular purchase intention (CPI) in Greece and the United Kingdom. A cross-national online stimulus-based survey utilizing standardized e-commerce product-card claims for a fictitious circular fashion brand gathered data from Greece (n = 640) and the UK (n = 572). PLS-SEM and multi-group analysis evaluated a model distinguishing CSQ and CSC as complementary message properties. In the overall sample, both CSQ and CSC exhibited a positive correlation with CPI, whereas PGA and GTR emerged as the most significant proximal predictors, with authenticity demonstrating the most substantial impact. Indirect-effect tests showed that CSQ affected CPI through both authenticity and trust. On the other hand, CSC was only effective through authenticity, and there was no clear pathway for CSC trust intention. The multi-group results also showed context sensitivity: Greece exhibited a stronger trust-based path to intention, while the UK had a stronger authenticity-based path to intention. Overall, the results support a dual-route theory of CE claim persuasion. Additionally, they suggest that effective CE fashion communication should combine clear, specific content with credible, externally checkable support cues.