This paper describes the key principles of why an assessment of uncertainty and its consequences are critical for the types of decisions that a body such as the UK National Institute for Health and Clinical Excellence (NICE) has to make. In doing so, it poses the question of whether formal methods may be useful to NICE and its advisory committees in making such assessments. Broadly, these include the following: (i) should probabilistic sensitivity analysis continue to be recommended as a means to characterize parameter uncertainty; (ii) which methods should be used to represent other sources of uncertainty; (iii) when can computationally expensive models be justified and is computation expense a sufficient justification for failing to express uncertainty; (iv) which summary measures of uncertainty should be used to present the results to decision makers; and (v) should formal methods be recommended to inform the assessment of the need for evidence and the consequences of an uncertain decision for the UK NHS?