Feasibility beyond Non-ideal Theory: a Realist Proposal

Some realists in political theory deny that the notion of feasibility has any place in realist theory, while others claim that feasibility constraints are essential elements of realist normative theorising. But none have so far clarified what exactly they are referring to when thinking of feasibility and political realism together. In this article, we develop a conception of the realist feasibility frontier based on an appraisal of how political realism should be distinguished from non-ideal theories. In this realist framework, political standards are feasible if they meet three requirements: they are (i) politically intelligible, (ii) contextually recognisable as authoritative, and (iii) contestable. We conclude by suggesting that our conception of realist feasibility might be compatible with utopian demands, thereby possibly finding favour with realists who otherwise refuse to resort to the notion of feasibility.


Introduction
When political realism started to attract the attention of scholars working on the methodological debate in political theory, it was not uncommon to interpret it as an approach that constrains political normativity with feasibility concerns (Valentini 2012;Freeden 2012). In that (original) interpretation, feasibility was understood as implementability, and, accordingly, the realist perspective was interpreted as determining the principles for action given the political circumstances in place. While this initial conflation of political realism and implementability concerns has been confuted in several ways (Geuss 2016;Sleat 2014b;Raekstad 2016;Rossi and Sleat 2014;Rossi 2019), what meaning and normative relevance (if any) feasibility should assume in realist political theory is still largely underexplored.
Aside from being scarce, realists' references to feasibility contrast with one another. Some realists argue that political realist theorising need not include feasibility constraints. In maintaining this, they usually refer to feasibility as traditionally conceived of within the debate between ideal and non-ideal theorists-namely, as a constraint on utopianism in theorising the norms responsible for action guidance. Take Rossi's (2019) conception of prefigurative politics. Since he wants to accommodate some forms of utopianism in his normative proposal, he takes feasibility constraints as contrasting with the utopian character of his preferred version of political realism-namely, radical realism. 1 Other realists, conversely, have listed feasibility among the notions composing realist theorising. For example, Galston (2010) argues that "the art of reform is to locate the outer perimeter of the desirable possible and to use it as a guide for action in the here and now" (401). However, he admits, the difficulty lies in determining what is feasible and infeasible in a way that preserves the normative import of political theory without turning it into "science fiction" (Galston 2010, 403). Galston speaks of an "experience-based concept of feasibility" (400-401) and claims that feasibility for realists concerns not only the implementation of principles, but also, or primarily, their conceptualisation (405). In a similar vein, Jubb (2015Jubb ( , 2017 argues that political realism can support egalitarian reforms as long as, among other things, they do not require actions that go beyond what is politically possible in a given context. Finally, Philp (2007Philp ( , 2010Philp ( , 2012 describes political realism as an approach to political theory that assigns a central role to political feasibility in evaluating political actions.
In this paper, we provide a first inquiry into the relationship between realism and feasibility, and we do so with a specific focus. To conduct our inquiry, we proceed by examining the methodological literature that has analysed the role of feasibility in ideal and non-ideal theory. While realists' insights about the role of feasibility in normative political theory are scattered, their refusal to conflate political realism and non-ideal theorising is better elaborated and proves insightful to address the stated relationship.
By borrowing the notion of a "feasibility frontier" from David Wiens (2015b), we inquire into how the normatively relevant feasibility frontier should be conceived of in political realism-that is, what the ultimate border of political possibilities that must constrain realist political theory is. Any normative theory that presupposes or prescribes political possibilities falling outside that feasibility frontier ought to be considered invalid. In section 2, we explain how realism should be differentiated from two types of non-ideal theory and how that distinction grounds our proposal for conceptualising the realist feasibility frontier. In section 3, we explain that the feasibility frontier is given by states of affairs that are (i) politically intelligible, (ii) contextually recognisable as authoritative, and (iii) contestable. As we show, this definition of the normatively relevant feasibility frontier sits on a middle ground between the extant ones: the more expansive frontier adopted by ideal theorists and the less expansive one ("nonparasitic", as we call it) defended by non-ideal theorists. In concluding, we argue that the realist feasibility frontier proposed here is compatible with utopian vocations and can therefore be accommodated by realist theorists that are sceptical of its use (section 4). By clarifying the notion of political possibility in realist terms, the article contributes not only to the literature in prescriptive realism-which is focussed on "placing recommendations (…) for political action" (Freeden 2012, 1)-but also to the literature in interpretive realism-which focusses on how to interpret "empirically ascertainable manifestations of political and ideological practices" (Freeden 2012, 1)-in order to provide an appropriate picture of the political realm. 2 2 Political Realism and Non-ideal Theory Originally, the notion of feasibility was associated with non-ideal theory. John Rawls, who first introduced the distinction between ideal and non-ideal theories in political philosophy, interpreted the task of non-ideal theorising as reflection on the requirements of justice given actual feasibility constraints (Rawls 1971). While realists have not said much about how to conceive of feasibility in realist terms, they have endeavoured to distinguish themselves from non-ideal theorists. Hence, realists' critiques of non-ideal theorising prove a useful starting point to understand how political realism is supposed to conceive of the role of feasibility constraints in political theory and, consequently, to further distinguish realism from non-ideal theory.
In the literature, we find two types of non-ideal theory. One is "parasitic" to ideal theory (Sleat 2013, 10) in that it conceives of non-ideal theory as an adaptation of ideal theory to the circumstances of real politics (Simmons 2010). Principles are conceptualised in abstract or idealised 3 political circumstances and subsequently applied to real political contexts. The other type of non-ideal theory, conversely, is independent of ideal theory, insofar as principles are elaborated straightforwardly by considering the complexities of real political circumstances. According to the latter, ideals are unnecessary for understanding what ought to be done in actual political circumstances (Sen 2006;Wiens 2015a).
We now systematise our understanding of the realists' normatively relevant feasibility frontier by explaining why both these interpretations of non-ideal theorising are incompatible with some of the fundamental commitments of realist political thought.

Political Realism Versus Parasitic Non-ideal Theory
The notion of feasibility was originally introduced to elucidate the distinction between ideal and non-ideal theory (Rawls 1971). 4 In its parasitic form, non-ideal theory differs from ideal theory because it takes into consideration the circumstances in which the principles are expected to be applied (Stemplowska and Swift 2012). Importantly, while standards for action-regarding, for example, individual action, institutional change, or collective decision making-are modified based on an appraisal of the circumstances of politics, the principles informing those standards (for example, principles of justice or equality) need not be subject to practice-driven adaptations. Thus, Sangiovanni (2008b) recalls, the notion of feasibility "is best understood as a virtue of public policies rather than of conceptions of justice. It is a virtue which obviously requires attention in 'designing' social and political institutions, but principles of justice themselves are not immediate candidates for rejection on the basis of their 'infeasibility'" (224). In sum, parasitic non-ideal theory differs from ideal theory in that it regards ideal theory as deficient in its ability to provide action guidance here and now, and it therefore suggests introducing feasibility constraints to shed light on how to proceed in realising the ideal in non-ideal political circumstances.
However, those who have further engaged in systematising the concept of feasibility in relation to the notions of ideal and non-ideal theory have claimed that both ideal and non-ideal theory could be subjected to some form of feasibility constraint but that the constraints' role and conceptualisation ought to be understood in substantively different ways. While ideal theory ought to be subjected to hard constraints such as logical, nomological, biological, or metaphysical constraints (Estlund 2014, 116;Gilabert and Lawford-Smith 2012, 813;Lawford-Smith 2012, 252-53), non-ideal theory ought to be also subjected to soft constraints-those that track the actual probability of political goals occurring, such as limited human ability, limited resource availability, technological limitations, institutional constraints, and cultural factors (Gilabert and Lawford-Smith 2012, 813).
In the context of this distinction between ideal and non-ideal theory, and their respective uses of the notion of feasibility, Matt Sleat offers the most systematised contribution on the difference between political realism and parasitic non-ideal theory. We think that his insights are helpful for shedding light on the difference between how political realism conceives of and employs the notion of feasibility and how non-ideal theory does. As Sleat (2014b) explains, differently from political realism, the debate surrounding the relationship between ideal and non-ideal theory has developed on the grounds of the undisputed assumption that liberal political theory is not to be contested: "Neither liberal politics nor theory is at stake in the ideal/non-ideal theory debate, however conceived. This debate is . . . directed exclusively towards the question of how one does liberal theory" (30). The problem is not necessarily the liberal character of the ideals involved in this mode of normative theorising; Sleat (2013), indeed, is an advocate of liberal realism. Rather, the problem lies both in the assumptions grounding mainstream liberal theory and in its way of conceiving of the relationship between theory and political reality. As Sleat (2014b) shows, the adverse realist position on liberal theory is motivated by two points of disagreement: the "assumption that the function of politics is to resolve conflict" (34), and the "attempt to make the moral prior to the political" (34).
Classical liberal theory conceives of political philosophy as an endeavour aimed at identifying political values or ideals that could be in principle recognised as justified and authoritative by everyone-provided a correct use of reason. In contrast to that approach to political theorising, realists argue that one of the fundamental facts liberals fail to recognise about politics is that conflict cannot be resolved, as conflict is constitutive of politics (Galston 2010;Philp 2010;Rossi and Sleat 2014). Conflict arises not only among different interests, but also among different worldviews and moral perspectives. In fact, according to realists, politics is necessary precisely because we cannot agree upon which values or ideals should regulate the political (Sleat 2014a, 322;Williams 2005, 3). Crucially, for realists, understanding the pervasiveness of conflict means recognising that even if moral truth were reachable, the problem of conflict would remain as a specifically political issue to deal with, as conflict cannot be eliminated by invoking reason and seeking cogent philosophical arguments (Rossi and Sleat 2014). In a similar vein, Williams argues that a political situation is one in which there is a clash of stances that requires a political decision, rather than a philosophical dispute. For him, a political decision is one that "does not in itself announce that the other party was morally wrong or, indeed, wrong at all. What it immediately announces is that they have lost" (Williams 2005, 13).
Realists seek to emphasise that political normativity must be influenced by the fact that the first issue politics must address is that of making possible a legitimate order out of conflict (Williams 2005, 3). Recognising this has crucial consequences for political normativity: first, political normativity must be shaped in accordance with the contextual conditions under which the authority is acknowledged as legitimate; second, legitimate orders are not attainable without a certain amount of coercion, given the impossibility of achieving full consensus on the legitimate ordering principles. By failing to assign such justificatory weight to political reality, political theory would risk prioritising the wrong issues (for instance, justice over legitimacy) or dangerously defending impracticable prescriptions (for instance, those incompatible with the conditions for the attainment of legitimate recognition). Accordingly, in contrast to the liberal approaches that deem the moral as prior to the political, realists argue for the need to regulate politics by reference to "justificatory resources that are internal to politics" (Sleat 2014a, 317).
It is precisely for this reason that, according to Sleat, political realism cannot be equated with non-ideal theory: the problem of realism-in contrast to non-ideal theory-is not to make ideal theories more practicable; rather, realism is interested in making political theory adequate to its object of investigation, namely political reality. In other words, political realism aims to offer a corrective to the justificatory structures of political theories rather than to their applicability (Sleat 2014b, 30-31).
Such considerations are helpful to understand why realists would reject the conceptualisations and the roles attributed to the notion of feasibility as associated with both ideal and non-ideal theorising understood in a parasitic sense. As for ideal theorising, the feasibility frontier employed in it is unduly fact-insensitive since the hard constraints employed in ideal theorising are too far from actual politics to ground a normative theorising that realists find appropriate. Realists criticise ideal theory for its inadequacy to the object rather than for its inapplicability: an ideal theory could be applicable but, given its nonpolitical foundations, its application could have results that are dangerous, non-action-guiding, or irrelevant (Sleat 2014b, 36-37;Mills 2005;Philp 2008;Prinz and Rossi, 2017). This implies that for realists, an understanding of both general and contextual features of politics must constrain any normative theorising regarding politics, not only the theorising devoted to providing action guidance in real political circumstances. 5 In this sense, realists differ from parasitic non-ideal theorists, who, conversely, distinguish between abstract and practical theoretical focuses, where the former conceptualises principles bracketing an appraisal of actual political circumstances, while the latter analyses the principles to be applied to the political context. A case in point is David Estlund's view of political theory. By defending the goodness of a theory of justice despite its eventual incapability of providing action guidance, he must assume that practical concerns are not relevant for defining a concept such as justice but matter only for determining how to approximate that concept in reality (Estlund 2014(Estlund , 2020. Similarly, Barry and Valentini (2009) and Cohen (2001) argue that practical concerns apply to the implementation of principles, not to the principles themselves, and Buchanan (2004) separates theorising about principles from theorising about the principles' implementation.
As for parasitic non-ideal theory, despite making use of descriptive constraints that are more fact-sensitive than the ones employed by ideal theorists, it conceives of the role of feasibility in the wrong way. Ideal theorists start normative theorising by abstracting from actual politics. Conversely, realists start normative inquiries by appraising political practices. In other words, in ideal theorising, politics matters as a constraint on the output of theories; that is, it affects how theories ought to be adapted after they have been elaborated. In political realism, the circumstances of politics constrain the inputs of theories; that is, they ought to be taken into consideration before theorising.
Parasitic non-ideal theory privileges a top-down form of normative theorising in which principles are prepolitically formulated and subsequently applied to different political realms. In contrast, political realism insists on the need to theorise in a bottom-up fashion-that is, in a way that starts from an appraisal of the political practices under consideration. In this sense, analysing the political context is prior to conceptualising normative standards; it is the necessary condition for elaborating normative principles. Accordingly, feasibility takes the form of a normative constraint on the conceptualisation of principles. Conversely, for nonideal theorists the analysis of the political context is subsequent to the conceptualisation of normative standards and in some cases is even unnecessary for the elaboration of normative principles (Cohen 2003). Accordingly, in the debates about parasitic non-ideal theory, feasibility takes the form of a normative constraint on the implementation of normative standards.

Political Realism Versus Nonparasitic Non-ideal Theory
It seems then that nonparasitic forms of non-ideal theory could be more promising as candidates for providing a realist interpretation of feasibility. For example, in Wiens's view, 6 normative political theory is fundamentally contextual. Thus, his interpretation of the notions of both feasibility and non-ideal theory might easily sound realist-like and more promising than the parasitic version.
In a series of recent articles, Wiens (2012Wiens ( , 2015aWiens ( , 2015b has investigated the notion of the feasibility frontier, by which he means the ultimate limit of the political possibilities that are accessible to us. Wiens advocates a specific interpretation of the feasibility frontier-the restricted-possibility account-which builds on economists' concept of a production possibility frontier. In economics, the production possibility frontier defines the set of commodity bundles we can produce given the production functions of each commodity (production processes) and the constraints that apply to the production inputs, such as labour, capital, and materials (resources) (Wiens 2015b, 452). Accordingly, the feasible production set is constituted by the set of bundles that fall within the frontier so defined.
In order to provide a definition of the feasibility frontier for political theory, Wiens modifies the notion of the production possibility frontier to make it suitable for analysing political practices. Starting with the "resources" that ought to be considered, Wiens believes that an appropriate analysis of political possibility ought to take into account all elements that have a role in altering the status quo. These political resources include not only hard (fixed) constraints such as logical consistency, laws of nature, and human biology, but also soft (malleable) constraints such as ability, cognitive, economic, institutional, technological, and motivational constraints. The introduction of motivational constraints as one of the factors shaping the feasibility frontier is a salient feature of Wiens's account. For Wiens (2015b), motivational constraints "identify the limits of what people can be motivated to do given intrinsic features of human agents that affect motivation (including affective biases, prejudices and fears), as well as the extrinsic features of an agent's environment that interface with her intrinsic motivational capacities (including social norms and incentives)" (453). That is, Wiens argues that what is politically feasible is affected by-among other things-our collective capacity to move towards the realisation of a certain goal. Note that this is a stringent requirement in the definition of the feasibility frontier. 7 As noted above, however, knowing which resources we have at our disposal is not sufficient to know how the feasibility frontier ought to be defined. We need also to specify what can be done with the resources available. Wiens argues that the set of the feasible political worlds accessible to us is determined by two kinds of processes. First, the use of available resources can directly produce the desired outcome. If we can identify a causal chain leading (through the use of available resources) from the present state of affairs to a new one, then the new state of affairs falls within the feasibility frontier. Second, available resources might be employed to produce other resources, which, in turn, produce the desired outcome. When used for this purpose, our available resources have an indirect role in affecting the feasibility frontier. Overall, for Wiens, the feasibility frontier equates with the states of affairs that are achievable given the resources at our disposal, the causal processes that can be enacted, and the possible conversions between resources.
There are two important inferences Wiens draws from this analysis regarding the practice of normative political theorising that matter for the purposes of our argument. First, Wiens claims that an analysis of the feasibility frontier ought to have priority over ideal theorising in normative political theory. Wiens explains that this should be the case because-as we have just noted-the restricted-possibility interpretation of the feasibility frontier imposes stringent conditions upon the states of affairs that we could deem feasible; therefore, it is entirely possible that the practical goals set by the ideal theory will fall outside the feasible set. Yet Wiens argues that when ideal objectives prove infeasible, the best option to pursue might not coincide with the one that best approximates the ideal. 8 Hence, ideal theory cannot be merely applied to non-ideal circumstances; rather, we should first define the feasibility frontier and then search for the ideal option that falls within that boundary. This explains Wiens's refusal to conceive of non-ideal theory as parasitic to ideal theory.
Second, Wiens believes that it would prove useless, and possibly unwise, to search for the best accessible political world within the feasibility frontier so defined. Wiens explains that identifying the feasibility frontier by following the restricted-possibility account would entail a calculus far too complex to undertake with our limited means since it would require us to possess complete knowledge of the available resources at our disposal and the causal mechanisms available to us. Given a similar complexity, it might be impossible to figure out 7 By allowing motivational constraints to affect the feasibility frontier, Wiens takes a stand against the popular conditional-probability interpretation of the feasibility frontier, which asserts that we should regard as achievable all those states of affairs that could be realised if agents were to try to realise them (Lawford-Smith 2012). Otherwise, the proponents of the conditional-probability account claim, we would let agents easily off the hook and we would come to regard some political circumstances as the best we can hope for simply in virtue of our laziness as political agents. 8 To claim this, Wiens resorts to the general theory of the second best as elaborated in Lipsey and Lancaster (1956). whether a political goal far from our immediate reach is feasible and, consequently, it could be dangerous to pursue it.
Hence, for Wiens, normative political reasoning should be conducted not by identifying and seeking ideal political goals, of which we would need to ascertain feasibility, but rather by trying to remedy actual injustices and focusing on our immediately accessible practical possibilities. In this sense, according to Wiens (2015b), normative political reasoning devoted to enhancing progressive changes in society should look not forward, but rather backwards: "Instead of trying (against all odds) to chart an uncertain transitional path toward a risky goal, we reorient normative theory to focus on concrete social failures rather than political ideals" (471). Thus, moral progress should be conceived of as progress from actual injustices, rather than progress toward an ideal goal (470-72). That is, according to Wiens, normative political theory should be aimed at remedying-where possible-what we can identify as clear cases of actual injustices. Overall, Wiens argues that exploring the limits of our practical possibilities and, accordingly, doing ideal theory are useless exercises in normative political theory insofar as we are trying to understand what ought to be done in specific political circumstances.
At first sight, Wiens's analysis of the feasibility frontier and its role in normative political theory might be identified as a realist approach to the feasibility issue for three reasons. First, like Wiens, realists believe that the motivations of political agents ought to play a crucial role in assessing what political goals ought to be judged as practicable and, relatedly, ought to be pursued (Galston 2018;Geuss 2008;Philp 2010). Second, recall that Wiens argues that normative political theorising ought to begin with an appraisal of the feasibility frontier and that political ideals ought to be identified only afterward, within the boundaries of the defined feasibility constraints. Similarly, for realists, normative political theory ought to start with accurate appraisal of actual political contexts, rather than with abstract theorising, and should be construed on that basis. As we explained in the previous section, for realists, political reality is not merely a field of application of ideal theories, but also plays a role in the conceptualisation and justification of ideals (Rossi and Sleat 2014;Sleat 2014b). Third, for Wiens, our political choices and actions ought not to be conceived as steps towards the achievement of an ideal target. In fact, Wiens believes that determining what ought to be done should be the result of a contextual evaluation aimed at identifying the strategies that allow us to overcome injustices here and now. Similarly, realists do not conceive of political actions as means towards the achievement of the ideal (Philp 2007;Rossi 2019). Rather, political actions ought to be assessed on the basis of contextual political judgements taking into account a series of contingent variables. For realists, there is no clear recipe for establishing what ought to be done here and now; rather, choices must be made case by case (Philp 2007;Geuss 2010, ch. 1).
Despite such affinities, we believe that Wiens's analysis of the feasibility issue cannot be adopted by realists. The comparison with Wiens's approach is enlightening in order to point out what specifically characterises a properly realist notion of feasibility. Specifically, realists might have a problem with Wiens's thesis about the alleged uselessness of political ideals for actual political action. As we have seen, Wiens claims that the feasibility frontier is ultimately unknowable. From this consideration, he further argues that we must overcome a conception of progress as progress towards ideal justice and substitute it with a conception of progress as progress from injustice. Such a change of perspective should-in Wiens's opinion-overcome the problem of the unknowability of the feasibility frontier. As explained above, Wiens's (2015b) strategy consists in claiming that normative political theory should focus on remedying social failures, where "'social failure' refers to a state of affairs that is morally inferior to (known) feasible alternatives according to our evaluative criteria" (471, emphasis added), rather than seeking to achieve far-away objectives whose feasibility is inevitably uncertain. In a sense, then, Wiens overcomes the problem of the unknowability of the outer feasibility frontier by letting normative political theory rely on a more restrictive feasibility threshold. Since we cannot grasp a larger set of practicable options, we need to rely on the narrower set of possibilities that we are able to know-namely, the threshold of the "(known) feasible alternatives".
This argument is problematic for realists because it presupposes a reductive picture of the complexities of the political realm and of the relationship between theory and political practice. Political processes are always to a certain extent unpredictable because of the unpredictability of human behaviour and the complexity-as Wiens himself recognises-of political processes. Hence, the feasibility of political outcomes can never be fully known: we cannot know whether some political goal is feasible if feasibility means identifying a clear causal path towards that goal. In fact, the divide between knowable and unknowable is more suitable for describing scientific inquiries in which the phenomena investigated behave in a deterministic way than for scrutinising political phenomena. Contra Wiens, such a divide is not sharp, because human actions are not explicable merely in determinist terms: at best, we might be able to maintain that a certain course of action is likely to occur, but we can never be certain about its eventual occurrence. Hence, it is for us to decide how much knowledge we need to have in order to ground political decisions and, in turn, whether to prescribe only courses of actions that have high probability of success or to aim at states of affairs that are more unlikely to succeed in virtue of their desirability. Therefore, the feasibility thresholds we consider relevant for normative political theory are always the fruit of a normative evaluation of what should ground a political judgement. In this sense, Wiens's language of knowable and unknowable obscures the complexity of political judgements, as it treats them as judgements depending uniquely on allegedly objective characteristics of the political circumstances under scrutiny.
How can such an evaluation be undertaken? Notice that, since feasibility thresholds are actively chosen and not simply discovered, fixing them involves costs: by deciding that a certain degree of probability of success is normatively relevant, all goals that are judged to be too remote to be achievable come to be discarded-even those that are highly desirable. This is why-we claim-in order to establish the relevant threshold we need to explore the possibility of desirable political scenarios that are beyond the limits of what is realisable here and now. 9 Surely, as realists often emphasise, political decisions are extremely complex: deciding to pursue one course of action rather than others depends on, among other things, the balance of gains and losses (Philp 2010). When the political options that are easily accessible are highly disadvantageous, it might be preferable to pursue a course of action that has a low probability of success (Geuss 2010, 12-16). The status quo might be considered so problematic that the desire to change it might motivate action regardless of the costs involved in overcoming social failures. Therefore, we argue, exploring the borders of the feasibility frontier is necessary for both forward-looking and backward-looking conceptions of progress. Hence, the problem of the alleged unknowability of the feasibility frontier Wiens raises cannot be resolved by simply relying on a backward interpretation of progress.
However, it could be objected to our argumentation that realists tend to start from the summum malum rather than from to the summum bonum, and that they see the role of political theory as to provide standards for action in the here and now. In addition, the objection might go, realists are well aware that while it is relatively easy to agree on the injustice of a given state of affairs, it is much more complicated to agree on which overarching view would ground the perception of such injustice in the here and now. These considerations would at least partly soften our critique to Wiens, the objector might claim: in fact, it seems that it is not always the case that in order to make political judgments in actual contexts we require some reference to an ideal standard. While these aspects surely pertain to realist thinking, we do not think they corrode our critique to Wiens' account for two reasons. First, even if there can be political circumstances in which the feasibility frontier is clearly defined, that is, those circumstances in which our political options are very limited, these are exceptional cases, as we argued earlier.
In contrast, in all those other cases in which the set of our political options is not clearly delimited, our critique to Wiens remains sound: in order to properly justify the feasibility frontier we need some reference to ideal desirability. Notice, second, that our critique would hold even if political judgements were driven by the summum malum, rather than by the summum bonum: in fact, political theorising can be driven also by negative ideals, as for example Judith Shklar suggests when conceiving of the task of politics in terms of avoiding fear (1989). In these cases, a decision about what actual changes we are reached to bring about would be justified by seeking the greatest departure from the least desirable state of affairs, given an adequate balance of the gains and losses expected.
Let us summarise what we learned by comparing realism and non-ideal theory. Political realism cannot coincide with parasitic non-ideal theory, as this would compromise the bottomup type of normativity that realism favours. However, it also cannot appeal to Wiens's restricted-feasibility frontier, as realism aims at considering desirable states of affairs that are beyond what is realisable here and now. Finding such a balance is further complicated by the fact that we might be unable to precisely determine how feasible it is to bring about a certain state of affairs. Is realist normative political theory then stuck between the necessity of exploring the feasibility frontier and the inability to know it? In the third section, we defend an alternative definition of the feasibility frontier that overcomes the problems Wiens's account encounters.

Realist Feasibility
How does this discussion contribute to defining the normatively relevant feasibility frontier in a realist sense? We said that political realists want to distinguish themselves from non-ideal theorists. Hence, a realist understanding of the feasibility frontier must vindicate such a difference. So far, we have seen that realists cannot trace it by employing the strategies adopted either by parasitic non-ideal theorists or by non-ideal theorists à la Wiens. They must reject the former model because feasibility must apply not to the implementation of standards but to their conceptualisation and because realism is committed to bottom-up normative theorising. In addition, they must reject Wiens's proposal because it unduly limits the set of political options to those that are known to be accessible here and now.
What does it mean, then, for a standard to be feasible in a realist sense? We said that a standard is feasible if it is appropriate to the realm of politics and to the specificities of the political contexts under scrutiny. Hence, to understand the terms in which a standard is feasible, we must go back to what realists have said about politics and the methods of political theory vis-à-vis what non-ideal theorists have said.
That the boundaries of feasibility are dependent on the notion of politics can be understood by considering Williams's and other realists' notion of "political intelligibility". Williams (2005) argues that "the distance of that possible world from the actual world must be measured in terms of political considerations of relevance and practical intelligibility" (92). Thus, political standards are intelligible when they meet two conditions: first, they are compatible with the realm of politics (that is, they are standards for how the political authority should be exercised, given what politics is); second, they make sense as standards to those subject to the political authority (that is, they are compatible with the values held in a given political community).
Then what does it mean for a standard to represent a normative possibility for regulating politics? We saw that one matter on which non-ideal and realist theorists differ concerns the way in which they conceptualise conflict in particular and politics more broadly. Accordingly, the realist feasibility frontier must account for the ineradicable nature of conflict not simply as one fact among others, but as a defining element of politics. That conflict is ineradicable must influence the formulation of normative principles. Therefore, normative standards fall within the boundaries of the feasibility frontier when they prescribe objectives that are compatible with the conflictual nature of politics.
Consider again liberal theories of politics. While it is notably hard to exactly define the common traits of liberal political theories, they share an underlying intent that has been most clearly expressed by Jeremy Waldron (1993): "The thesis that I want to say is fundamentally liberal is this: a social and political order is illegitimate unless it is rooted in the consent of all those who have to live under it; and the consent or agreement of these people is a condition of its being morally permissible to enforce that order against them" (50). Notice that liberal theorists recognise that actual consent is an impossible goal to pursue in actual political circumstances. Hence they often rely on the idea of tacit or hypothetical consent to justify their proposals. Yet realists believe that searching for the (hypothetical) conditions for achieving consensus about a set of political principles is a fundamentally wrong way to go in political philosophy. The point is that, as said, since a consensus about normative principles is impossible to reach in real politics, wondering what principles would be adopted in idealised circumstances means asking the wrong questions and, consequently, elaborating normative principles irrelevant to or inadequate for political circumstances (Horton 2010, 434). The problem is that in contemporary "mainstream" liberalism, resolving conflict by getting consent is compatible with the idea of politics, as if there is-at least in principle-a distinction between actual (dirty) politics and its (clean) essence and the two should be reconciled. 10 For realists there is not an image of politics that is distinct from what politics is here and now, and, consequently, there is no image of politics that does not include conflict in its defining traits (Sleat 2016). A normative political standard grounded in the possibility of ending conflict is an unfeasible standard for realists. What is feasible, conversely, is a standard that takes seriously the necessity of ensuring subjects' compliance in order to manage conflict and keep it under control and examines the implications of such a practical problem.
That politics is a certain type of entity has further implications for how political standards have to be formulated in order to be feasible ones. In fact, since politics is a sphere independent of the moral one, its normativity must vindicate the priority of politics over morality. The problem realists have with the application of external moral standards is not their moral connotation but their origin outside of politics. In fact, Sleat clarifies, moral considerations do play a role in politics, as they contribute, together with other types of considerations, to delineating what makes sense as a justification of power to the subjects of a given polity (Sleat 2014a). These considerations can turn into standards that might be moral in character, but nonetheless internal to the political sphere under assessment. Relatedly, a standard is feasible if it expresses a normativity that does not appeal to external prepolitical moral values, namely values whose moral validity is granted independently of any political consideration. To remedy this problem, we previously saw, realists reconceptualise the relationship between theory and practice in normative theorising and favour forms of bottom-up theory in which standards arise from an appraisal of the political practices under scrutiny. Accordingly, a standard is feasible if it originates in an appraisal of the practices, purposes, and objectives of the institutions regulating a specific political context (Jubb 2016).
Yet there is a second sense in which the notion of intelligibility should be interpreted, which then leads us to specify a further sense in which standards are feasible according to the realist perspective. We saw that moral considerations can play a role in the formulation of political standards but cannot express priority of the moral over the political and cannot be presented as having universal and undisputable validity. How then to know whether some moral considerations can be included in feasible political standards? The admissibility of moral considerations within the formulation of feasible political standards depends on what makes sense to subjects within structures of power and on whether those considerations contrast with the fact of politics (as we saw before when discussing the pervasiveness and permanence of conflict). Sleat (2014a) clarifies this point by highlighting that whether a certain demand for legitimation has been satisfied depends on several considerations to which subjects might appeal, including moral ones, because what matters for legitimacy is "that the political order makes sense as a form of legitimate authority in relation to the beliefs (moral, political, social, economic, etc.) of those who are subject to it, that it conforms to people's values and standards, and that it meets the normative expectations that we have of it" (325). Accordingly, a standard is feasible when it is held as a normative standard by those to which it supposedly applies. This sense in which a standard is feasible accounts for the contextual character of realist normative theorising, especially when considering the conditions for political legitimacy. For example, in this spirit Horton (2012) highlights the need to reconnect legitimacy and people's beliefs and attitudes. Both proposals take up Williams's (2005, 10) lesson that for a power relationship to be a political one, rather than a relationship of domination, the principles ordering the political order must make sense to those subject to them, given the cultural and historical circumstances in which those principles are to be applied. In fact, principles that do not make sense to those under their authority fail to be feasible because they fail to justify the exercise of political authority in a way that makes such an exercise look authoritative rather than arbitrary.
We said that feasible standards can include moral judgements about political circumstances but that, nonetheless, realists reject the claim that standards enjoy universal validity. This has a further crucial implication with regard to the feasibility requirements that ought to be placed upon realist political theories: normative standards are feasible in a realist sense when they are presented as contestable-that is, when their validity is presented as revisable and criticisable due to a change in the beliefs held by subjects in the considered context, or due to the clash of perspectives that appears even within the same political context. The contestability of standards vindicates a fundamental trait of the theory as a theory of politics because it does not hide the conflict underlying the individuation of standards by resorting to a delusionary image of consent as grounding the political order. Recall that realists regard the search for a consensus about political principles as politically unintelligible, meaning it is politically impossible given the essential features of politics. In this sense, realist normative standards are feasible-they fall within the boundaries of what is politically possible-when they are presented as contestable.
At this point, there is one last issue to tackle. As noted before, Wiens explains that only the states of affairs that are known to be feasible can be normatively relevant. For this reason, he claims that the ultimate feasibility frontier-as he defines it-cannot be considered the relevant feasibility threshold in normative theorising. Can the realist feasibility frontier so defined overcome the unknowability problem Wiens raises? We believe that the realist feasibility frontier as reconstructed so far does not have the same problem, because, contrary to Wiens's proposal, the realist feasibility frontier is not built on the idea of the production possibility frontier, which, as Wiens correctly explains, requires complex calculus to establish which objectives can be considered feasible. Indeed, the realist feasibility frontier is not defined by investigating which states of affairs we would ever be able to realise given present political circumstances. Rather, the realist feasibility frontier is defined conceptually and interpretively. As we saw, for the purposes of the realist feasibility frontier it is necessary to acquire a conceptual understanding of the boundaries of the politically intelligible and an interpretive understanding of its contextual specificities. Hence, since the realist analysis here developed does not rely on the notion of a production possibility frontier to define the boundaries of the politically possible, Wiens's unknowability problem does not apply to the realist account we have proposed.
Admittedly, some important questions remain open. The first regards how the conceptual and interpretive investigations ought to be properly conducted in order to formulate in-context political judgements. The second, and related, question concerns the epistemic problems possibly involved in such investigations. Addressing these issues, which we cannot presently examine and so we leave for further analysis, is fundamental in order to develop a full account of realist feasibility.

Conclusion: Realist Feasibility Meets Utopianism
In this article, we investigated how realists could conceive of the normatively relevant feasibility frontier in a way that does not overlap with the notions upheld by non-ideal theorists, thereby vindicating the difference between realist and non-ideal approaches in political theory. We argued that realist political proposals are feasible-that is, they fall within the boundaries of the realist feasibility frontier-when they are at least politically intelligible, contextually recognisable as authoritative and contestable.
In concluding, we want to circle back to where we started-namely, the different reactions to the notion of feasibility that realists have expressed. Realists that share a Weberian understanding of political normativity, grounded on the ethic of responsibility but nonetheless open to the ethic of conviction, 11 would easily embrace our interpretation of the realist feasibility frontier as crystalising the worries they have with regard to idealistic normative theorising. Indeed, theorists such as Galston, Philp, and Sleat have listed feasibility among the elements of realist theorising.
Yet can Rossi, and those who, like him, deny that feasibility plays a role in realist normativity, welcome our notion of feasibility? Does this interpretation of the realist feasibility frontier constrain the capacity of normative standards to move beyond the status quo? Or, conversely, can Rossi accept it without renouncing utopianism? We think he can, although fully discussing the relationship between the feasibility constraints that ought to apply to realist political theory and utopianism would require an effort beyond the scope of this article. Still, let us indicate some potential directions of argumentation. The realist feasibility frontier requires standards to be contestable and open to refinement, thereby avoiding conservative drifts. The feasibility frontier that is normatively relevant for realists, we said, is not as restricted as Wiens's one, as it does not need to include only those actions that are performable here and now. What is feasible is therefore not only what is compatible with the status quo. On the contrary, something can be feasible although it aims at subverting the current state of affairs. In other words, limitations do not concern the distance between the status quo and the desired state of affairs, but rather the nature of political standards and their compatibility with the realm of politics. Recall also that standards must be intelligible to subjects, and, insofar as they are-that is, they are conceptualised in a bottom-up fashion-they can even include moral considerations. In a similar way, utopias (intended in Rossi's sense as radical reforms) can fall within the boundaries of the realist feasibility frontier insofar as they are elaborated in a bottom-up way-that is, insofar as they are not imposed from outside politics, but rather represent objectives that subjects want to pursue and they do not elevate themselves to universal ideals enjoying incontestable validity.