This paper explores how Pyrrhonian scepticism, particularly as developed by Sextus Empiricus, interrogates the notion of rationality in both human and non-human animals. The debate over human rationality and non-human irrationality occupies a central place in both ancient and contemporary philosophy. The sceptics’ dialectical tool—rooted in the Modes of Suspension of Judgment, particularly the Ten Modes (Outlines of Scepticism, PHI 35–163)—aims to highlight conflicting impressions: cases in which something appears to have one property (F) under certain conditions and an incompatible property (F*) under others, thereby justifying suspension of judgment (Nawar, 2022). Central to this inquiry is the notion that impressions, whether of human or non-human animals, are variable, shaped by different parameters presented across  Modes. The Modes emphasise the perspectival nature of cognition and underscore longstanding philosophical divisions over animal rationality, from Aristotelian gradations of soul to the Stoic denial of logos to non-human animal (Long & Sedley, 1987; Sorabji, 1993). For Sextus, such conflicting impressions are not a reason to choose sides but grounds for epoché—a suspension of judgment that avoids dogmatism. The case of the (ir)rationality of both human and non-human animals thus deepens sceptical reflection on rationality itself, challenging not only anthropocentric epistemological hierarchies but also simplistic anti-anthropocentric alternatives. Instead of resolving the debate, the Pyrrhonian approach exposes the fragility of our conceptual distinctions and encourages a critical posture through suspended judgment regarding claims about rationality in any species.