Chapter 3 expands on the moral deficit introduced in Chapter 2, engaging the principle of proportionality to show how the dominant account of rational agency leads to the disproportionate delivery of desert in two ways: by maintaining an overly narrow basis of the desert calculus, and by failing to recognise degrees of moral blameworthiness. It draws on key findings from social psychology to understand the lag between doctrinal expectation and the reality of human behaviour, and to show how proportionality can be reinvigorated at culpability evaluation by aligning it with a clear social justice objective. Applying the Real Person Approach (RPA), the moral deficit is exposed as a failure to recognise inherent and situational vulnerabilities, and a recognitive doctrinal response is offered as a means of legitimising the Universal Partial Defence. The chapter also reconciles the RPA with retributivism, as the hegemonic approach to culpability evaluation.