Forthcoming in Journal of Moral Philosophy Review: M. v. Ackeren and M. Kühler (Eds.) The Limits of Moral Obligation: Moral Demandingness and Ought Implies Can (New York: Routledge, 2016), 210 pages. ISBN: 9781138824232 (Hbk). Hardback: £90.00. It seems reasonable to think that what we are morally obliged to do will be in some way connected to what it would be morally good for us to do. However, a familiar line of thought in moral philosophy holds that there are limits on what we can be morally required to do. First, it is claimed that there is a limit to how demanding moral obligations can be. Second, the principle of ought-implies-can holds that we can only be morally required to perform acts that we are capable of performing. The aim of this timely collected volume is to address this gap in the literature by collecting papers that investigate the interrelations between these two debates and the consequences for how we should understand the nature of moral obligations. The book certainly succeeds in achieving this aim and makes an important contribution to the literature on the limits of moral obligation. The book begins with a helpful and impressively comprehensive overview from the editors of the literature on moral demandingness and ought-implies-can. After that the book divides roughly in two, with half the chapters focused primarily on moral demandingness and half focused primarily on ought implies can. I will explore two general themes that arise from this collection, focusing on those chapters that are most relevant to these themes. One interesting theme that emerges is that the existing literature on moral demandingness appears to rest on an overly simplified conception of what constitutes demandingness. Brian McElwee argues that there is an important lack of clarity in the literature on demandingness concerning precisely how we should understand demandingness in this context (p.22). Where an explanation is offered, it tends to be given in terms of cost. McElwee persuasively argues that this way of understanding demandingness is insufficient. The reason for this is that the difficulty of an action also contributes independently to how demanding it would be to morally require that action from people. McElwee defends this claim through an appeal to the appropriateness of the sentimental reactions commonly associated with a failure to perform a moral obligation. According to McElwee, if someone is morally obliged to act in a certain way then they will be worthy of blame if they fail to act in that way. This is important because feelings of blame are less appropriate for the failure to perform a morally good act that is difficult than one that is easy. As a result, we need to accept that difficulty also has role to play in placing limits on moral obligation. McElwee then claims that ought-implies-can may simply be a limiting case of this more general principle. The issue of the insufficiency of cost conceptions of demandingness arises again in Claire Benn's discussion of the relationship between acts of supererogation (those that are beyond the call of duty) and moral demandingness. As Benn points out (p.70), a common thought in the literature is that supererogatory acts are those that are too costly to be demanded from people. After considering various ways of supporting this connection, Benn concludes that only 'The Confinement Objection', according to which a moral theory is too demanding if it confines the range of our permissible options, is plausible. However, a moral theory could avoid the confinement objection without making room for the supererogatory by allowing for the existence Forthcoming in Journal of Moral Philosophy of tied options (p.78). Benn concludes that there is only a contingent connection between supererogation and demandingness. The importance of getting clear on what exactly is meant by demandingness is further emphasized by Marcel van Ackeren's detailed discussion of Joseph Raz's view of moral demandingness. Reading these three essays together presents a convincing case that anyone wishing to object that a moral theory is too demanding ought to clarify exactly what is meant by demandingness. One way to do so is through a phenomenological investigation, as Sophie Grace Chappell does in her account of the way in which encounters with value can generate demands. One of Chappell's key claims is that encounters with value, unlike encounters with ordinary objects, can be epiphanies. These are, "revelations to us of something that founds, or that revolutionizes, the whole way we see the world and think about value," (p.85). This is an intriguing suggestion and Chappell does an exemplary job of motivating this thought through detailed discussion of examples from literature and history. However, more could have been said about exactly how we should understand what an epiphany is. Does Isaac Newton's encounter with a falling apple that led to his insight into the nature of gravity count as an epiphany? It seems that it should but it doesn't easily fit with the initial account Chappell provides, as it isn't clear that this insight changed the way Newton though about value (though it did of course change the way he thought about gravity). Another interesting theme to arise from this volume is the agent-relativity of demandingness. What is demanding for one person may not be demanding at all for another. This point is touched upon by McElwee and developed in greater depth by Vanessa Carbonell, who argues that we need to not only ask whether morality is too demanding but also asking for whom morality is too demanding. Carbonell makes a convincing case that the demandingness of morality will vary greatly from person to person. Particularly interesting is Carbonell's claim that certain obligations are triggered by the possession of a relevant form of knowledge (p.45), which as Carbonell points out may, "result in a stratified moral caste system, not to mention a disincentive to seeking education," (p.48). Garrett Cullity touches on a similar issue. Cullity investigates a common argument that morality cannot demand extreme self-sacrifice from people, as they are unable to meet this standard (p.147). According to this argument, the ought-implies-can principle is capable of grounding an argument against overly demanding moral views. Cullity argues that while there are oughts and cans for which it does the impact of this is limited, as we can then be demanded to make ourselves someone with a greater capacity for self-sacrifice (p.159). The possibility of an obligation to morally develop oneself might help Carbonell avoid some of the worrying implications of her view, such as the disincentive to seek education. While these contributions make important contributions to the literature on moral demandingness, the collection might have been improved by the inclusion of a discussion concerning whether there is any reason to take demandingness objection seriously. Dale Dorsey comes closest to addressing this issue. Dorsey argues that there is a tension between the scope of morality and its normative force. To relate this to the issue of demandingness, if we allow moral obligations to demand too much from us, then we run the risk of downgrading the normative Forthcoming in Journal of Moral Philosophy force of these demands. Dorsey claims that this trade-off presents moral theorists with a choice to make. Either we decide first on the normative force of morality and then investigate the scope or we decide on the scope first and then examine the normative force. Given this choice, Dorsey provides two arguments in favour of opting for the scope first approach. First, scope is intrinsic to morality while force is extrinsic. Second, Dorsey claims that we cannot explain the normative force of morality unless we have a prior conception of the content of its demands. Both arguments are interesting, though it isn't clear why we have to settle the content of either prior to asking about the content of the other. Why not think that we need to strike a plausible balance between the two? Dorsey's response is to claim that this approach would leave us without an explanation for the normative force of morality but this argument struck me as one that needed further elaboration. The issue of whether to take the proposed limit to morality is more central in the chapters that focus on ought-implies-can. Matthew Kramer argues that we should not reject the possibility of moral conflict on the basis of ought-implies-can. Ishtiyaque Haji, on the other hand, defends ought implies can against a number of possible critiques based on examples where an agent appears morally responsible for her act despite having been incapable of acting otherwise. In 'Why Does Ought Imply Can?' Robert Stern considers four prominent theories of moral obligation and investigates what, if anything, might ground this principle according to these wider views of obligation. The issue is also central in Michael Kühler's 'Demanding the Impossible', in which he argues that ought-implies-can is a moral principle not a conceptual claim about moral obligation. This is a fascinating collection of articles of that will be of interest to many working in moral philosophy and essential reading for all who work on the nature of moral obligation and its limits. Alfred Archer University of Tilburg a.t.m.archer@uvt.nl