Combining ideology with narrow self-interest in positive political theory

ABSTRACT Ideology and self-interest are often in tension. If positive political theorists assume broad self-interest as the standard of human behaviour, they can accommodate people’s ideological motivation to act for the common good. Yet, their theories may become tautological and empirically untestable. Conversely, if these theorists assume narrow self-interest, they increase testability. But because ideology seems incompatible with narrow self-interest, they often rule ideology out as a motivational driver. Positive political theorists can, however, combine ideology with narrow self-interest by assuming broad egoism. And in so doing, they should assume that ideology motivates political agents until it becomes too costly for these agents’ material interests.

aims. 9 It can accommodate people's ideological motivation to strive for the general good of society.But broad self-interest may become tautological and produce untestable models, 10 as one can always justify an explanation a posteriori by claiming 'the agents did X because they had a taste for it'.
If positive political theorists embrace narrow self-interest instead, it is harder for them to account for ideological behaviour.Narrow self-interest underpins the standard conception of homo economicus and tends to have a materialistic orientation. 11When theorists assume that material interests are the sole drivers of political action, ideology becomes irrelevant as a motivating factor, and thus narrow self-interest cannot accommodate it.Yet, ideology is likely to be a motivational driver.To assume the opposite seems like an oversimplification.Narrow self-interest often oversimplifies human behaviour.But this narrow version has a comparative advantage: it offers testable hypotheses and potentially useful predictions.
However, to remove ideology from RCT models of politics or to regard it as a mere proxy is a subpar solution, since it is difficult to explain phenomena like ideological movements or parties without considering the role of ideology as a motivating factor.After all, data shows that ideological beliefs can decisively influence political decisions, 12 and explanations based on mere material self-interest may sometimes look insufficient or inappropriate to explain ideological or politico-religious fervour. 13o advance its aims, positive political theory requires a general criterion to integrate ideology as a motivating factor into RCT models.In this paper, we propose such a criterion and defend its main assumptions.First, we explore the meaning of selfinterest and endorse the use of its narrow version.Then, we argue that positive political theorists can articulate ideology with narrow self-interest by assuming broad egoism.To do so, theorists ought to regard ideology as an important motivating factor, but also as a factor that political agents mitigate when ideological behaviour becomes too costly for their material interests.Such a proposal acknowledges ideology as an actual motivational driver while prioritizing material interests.
Our suggestion is of particular relevance to positive political theorists that use a textual approach and wish to combine ideology with narrow self-interest in their RCT models.They can profit from a clear and robust principle that helps them to analyse phenomena consistently without using mathematical modelling, thus maintaining some analytical flexibility within their formalized assumptions.
The paper is structured as follows.In the next section, we present positive political theory and its aims.Then, we discuss the meaning of self-interest and argue in favour of its narrow version -an assumption that public choice theory made prominent.Afterwards, we explain the model of expressive behaviour, which underpins our proposal to combine ideology with narrow self-interest.In the last section, we specify and defend such a proposal.When doing so, we distinguish it from other RCT approaches to ideology and beliefs.

Positive political theory
Positive political theory uses methods and models with particular assumptions to analyse political phenomena. 14Although this 'can refer to a wider array of analytic approaches and final goals [. ..], positive political theory, narrowly understood, means rational choice theory applied to the study of politics'. 15It is this narrow and more common understanding that we adopt when referring to positive political theory.Mathew McCubbins and Michael Thies note that: the very nature of the scientific method [of positive political theory] is to string together in a logically coherent fashion, a series of analogies about how the world works, in an attempt to improve our understanding of human behaviour. 16so understood as explanatory or formal political theory, positive political theory is positive, concerned with what is, making it distinct from normative political theory, which is concerned with what ought to be: 'positive political theory is explanatory or predictive, rather than normative or prescriptive'. 17Christian List and Laura Valentini claim that normative political theory 'addresses conceptual, normative, and evaluative questions, such as what a democracy is, how we ought to organize our political systems, and how to evaluate the desirability of policies'. 18To generate an explanatory and predictive theory about a particular phenomenon, one engages in the scientific process of understanding 'what is there'.This scientific realm is distinct from normative political theory, which is often not based on models of reality.Normative political theory usually relies on the non-formalized reflexions of the authors.As such, many scholars regard it as being outside of the scientific method, and instead located in the humanities.
The style of models in positive political theory can vary: a more quantitative style, such as game theory's mathematical modelling, can be used in the same way as a textual style based on logical reasoning: 'But whatever style is adopted, the underlying aim is clarity of communication, discussion and analysis'. 19The ultimate aim is to generate theoretical explanations that can offer useful and predictive insights into political phenomena, especially in the absence of extensive statistical data.These explanations can then be empirically tested or even potentially falsified in the future, perhaps when more and better data is available.
Such a methodological approach is embedded in the scientific method: 'The hallmark feature of positive political theory is its adherence to the scientific method of building up descriptive generalizations, or universal laws, from minimalist intuitive assumptions'. 20nitially, the researcher formulates a question about a certain aspect; secondly, the researcher generates a theory or chooses an already existing theory to answer the question; thirdly, the researcher derives predictions from the application of the theory; fourthly, the researcher designs an experiment/method of observation to test the prediction; and fifth, the researcher rethinks the initial research question.'The steps in the scientific method are separable from one another -not every Positive Political Theory project has to engage in every step'. 21ositive political theory usually relies on RCT models.These models assume that individuals choose the course of action that corresponds to their own preferences.Researchers use RCT models of human decision-making to better understand social behaviour in terms of rational actions, in which individuals choose according to some consistent criterion.The central idea of RCT is that individuals have preferences and choose appropriately. 22RCT is also an umbrella term for a variety of models explaining social phenomena as outcomes of individual action that can in some way be construed as rational.'Rational behavior' is behavior that is suitable for the realization of specific goals, given the limitations imposed by the situation. 23sitive political theory is then the study of socio-political phenomena based on assumptions and models that follow the standard rational choice principles of rationality, individualism and (generally assumed) self-interested preference satisfaction.Its goal is to generate a theory that explains and predicts how self-regarding actions of individuals combine to produce collective or social outcomes.To achieve this goal, rational choice is applied to political processes (such as elections and the platform formation of political parties), legislative behavior (such as coalition formation and bargaining), public goods (such as the 'tragedy of the commons' and the 'free rider'), and treaty formation and diplomatic strategy in international relations. 24 the same way as Thomas Hobbes or John Locke based their insights on a particular vision of how individuals behave in the state of nature, positive political theorists also theorize on the basis of particular rational choice assumptions regarding how individuals behave by default. 25Such theorists generate insights on social phenomena by logically deducing how individuals operate in certain contexts.For instance, when assuming that individuals are egoistic, a positive political theorist analysing a certain phenomenon would explain how egoists would behave in that context. 26

Self-interest: narrow and broad
In positive political theory, nearly all applied formal models involve thick rationality in assuming utility functions have specific function forms.One applies thick rationality when one not only assumes the rational ordering of preferences (e.g.completeness and transitivity), but also that preferences are more constrained; 'for instance, when individuals are assumed to pursue 'self-interest or to be "income-maximizing"'. 27 Indeed, using thick rationality in RCT models normally requires specifying the preferences and beliefs of individual actors as self-interested.And to determine how self-interest can incorporate ideological concerns, we must examine its meaning within RCT.
First, there is the narrow view of self-interest, which describes the individual as homo economicus, i.e. someone who is mostly interested in wealth and power maximization.According to Christopher Schroeder, 28 we can split narrow self-interest into two categories: broad egoism and material egoism.Broad egoism includes actions that individuals choose to directly (not indirectly) improve their well-being.Broad egoism permits certain forms of psychic well-being, 'such as the warm glow one may experience from participating in a winning political campaign' while 'psychological states produced by knowing that someone else's welfare has been improved are not included in broad egoism'. 29Put differently, other-regarding effects are not at stake when individuals choose actions under the assumption of broad egoism.
Material egoism applies when individual action targets material well-being 'either directly through income or wealth effects or indirectly by providing something that can be readily converted to income or wealth or that substitutes for something that would have to be purchased'. 30Self-regarding psychic enjoyment does not influence choices under assumptions of material egoism.The relationship between interacting individuals is thus of an economic nature and excludes altruistic behaviour 'towards those people with whom one is in exchange'. 31Geoffrey Brennan and James Buchanan, 32 for example, define the homo economicus as an egoist brute, devoting himself to maximizing the value of his measurable wealth.
However, the narrow view is challenged by a broad view of self-interest, which also considers non-egoistic traits, such as altruism, as part of the behaviour of the homo economicus.The broad view of self-interest presumes that the preferences that individuals try to maximize can be any form of psychic well-being.Namely, 'altruism, concern for the state of society, and additional other-regarding values can be a source of such individual well-being, often called psychic well-being'. 33To the extent that the broad view of self-interest harbours all types of preferences, it is compatible with ideological behaviour.
RCT models that use narrow self-interest achieve a parsimonious set of assumptions that produce empirically testable and hence falsifiable theories.However, this type of selfinterest may be easily falsified.Experimental research in behavioural economics has disproven the empirical soundness of the narrow self-interest assumption. 34In particular, experimental research shows that people are not only driven by concerns about material self-interest.Fairness, among other interests, matters to people.Bruno Frey and Stephan Meier, 35 for example, conducted an experiment in which they allowed students to voluntarily contribute to two social funds anonymously.The students contributed with substantial amounts, even though there were no benefits attached to these contributions.Instead of acting according to (material) self-interest, 'there are indications that a consideration of fairness and mutual benefit are important'. 36Social and economic factors seem to influence the degree of engagement in reciprocal behaviour. 37mpirically, the narrow view of self-interest seems to be refuted.Still, when using models that use the broad view of self-interest, which does not restrict preferences, the theories generated tend to become tautological, and hence, unfalsifiable. 38We can then explain all actions with a reference to preferences, as Robert Frank illustrates: If we see a person drink the used crankcase oil from his car, and he then writhes in agony and dies, we can assert that he must have really liked crankcase oil.(Why else would he have drunk it?)Virtually any behavior, no matter how bizarre, can be 'explained' after the fact by simply assuming a taste for it. 39en trying to understand if the utility function only contains narrow self-interested elements or if it also comprises other-regarding values, the dilemma becomes clear: If the utility function is left entirely open to considering actual human behaviour, the predictive power of the model decreases and the model may become unfalsifiable.By contrast, if the utility function is specified only by the maximization of narrow self-interest, the model does not illustrate real individual behaviour, but it has a high predictive power and can be verified or falsified in principle.While being conscious of the dilemma, most RCT scholars assign a higher value to predictive power and falsifiability than to open utility functions. 40o do we.In our view, then, the assumption of narrow self-interest is the better assumption to combine with ideology.But before explaining how this combination can be achieved, we must defend the use of narrow self-interest in RCT models of politics and address the critique that such an assumption is untrue and thus inappropriate for scientific use.

Defending narrow self-interest
The practice of assuming narrow self-interest and material egoism in the political realm achieved prominence in public choice theory (PCT) -a subset of positive political theory that applies rational choice models and economic tools to the study of politics.When classic public choice theorists apply their economic models to politics and society, they assume that material egoism motivates individual actors. 41Yet, as their behavioural assumptions can be empirically refuted, PCT is often criticized for still applying them. 42ome PCT scholars 'admit freely the possibility and indeed the likelihood of nonselfish behaviour in all institutional settings'. 43Buchanan, in particular, claims that, for predictive purposes, 'neither markets nor politics can be appropriately modelled in the strict (materialistic) formulation of the Homo economics construction'. 44Moreover, behavioural economists show compelling evidence that individual actors do not always behave as self-interestedly as PCT assumes: In undertaking dictator-games, ultimatum-games and public-good games they [behavioural economists] were able to show that -at least in some situations -individuals are much less self-regarding and far more other-regarding than traditional economic theory assumes. 45wever, PCT's assumption of rational self-interest is not a normative prescription.As Elinor Ostrom notes, 'complete rationality models', such as those conducted by PCT, are 'incorrectly confused with a general theory of human behavior'. 46Indeed, we can see PCT as an ideal type, not as 'a claim that self-interest explains all political behavior'. 47CT takes a conjectural form and builds models as if people were self-interested. 48hat is, it assumes that individuals behave as if they are maximizing their utility function.Milton Friedman 49 notably developed the 'as if' argument to defend models with unrealistic assumptions.Friedman uses the analogy of a billiards player: even though a professional billiards player does not rationally conduct complex mathematical formulas while playing, he makes shots as if he knew the formulas.Thus, a model that assumes full rationality of this billiards player may yield correct predictions about his shots.Models with unrealistic assumptions, then, may still generate useful predictions.
Friedman rebuts the idea that models lose their validity if their assumptions do not match with reality: Truly important and significant hypotheses will be found to have wildly inaccurate descriptive representations of reality, and, in general, the more significant the theory, the more unrealistic the assumptions (in this sense).The reason is simple.A hypothesis is important if it 'explains' much by little, that is, if it abstracts the common and crucial elements from the mass of complex and detailed circumstances surrounding the phenomena to be explained and permits valid predictions on the basis of them alone.To be important, therefore, a hypothesis must be descriptively false in its assumptions; it takes account of, and accounts for, none of the many other attendant circumstances, since its very success shows them to be irrelevant for the phenomena to be explained. 50iedman's instrumentalist approach, whereby he stated that unrealistic assumptions are irrelevant to a theory's validity and worth, has been highly criticized by other academics. 51As Paul Samuelson notes: 'The fact that nothing is perfectly accurate should not be an excuse to relax our standards of scrutiny of the empirical validity that the propositions of economics do or do not possess'. 52However, one must adopt a pragmatic view of science.What is meant by unrealistic assumptions?One can see an unrealistic assumption as untrue or incomplete. 53When analysing the criticisms made of public choice models, it is the assumptions' incompleteness that actually receives criticism.As those unrealistic assumptions are partly true, one ought to regard them as incomplete, not untrue.
The empirical reality is always complex, so it is unavoidable to rely on incomplete assumptions.The fruitfulness of a theory, explaining more with little, forces theorists to reduce the set of assumptions' sizes.To achieve models with high predictive power, it can be an advantage to adopt a more parsimonious approach: one that 'intentionally reduces people to a few individual characteristics', for a central feature of social science modelling 'is the focus on important aspects whilst disregarding less important matters'. 54 parsimonious theory with more unrealistic assumptions may then be more fruitful than one with many realistic assumptions, since the former allows theorists to work with key behavioural aspects, while the latter may focus on more realistic aspects, but on less important or unworkable ones.

Expressive voting and rational irrationality
Our proposal to combine ideology with narrow self-interest builds on Geoffrey Brennan and Loren Lomasky's expressive voting model, which they notably advance in Democracy and Decision: The Pure Theory of Electoral Preference. 55In this work, they answer to the 'paradox of voting', that is, to the question of why people vote at all when their individual vote is unlikely to decide any major election. 56They conclude that, by and large, people do not vote instrumentally, meaning that individuals do not vote for candidates that serve their material or private interests.Rather, people vote expressively to show support for a candidate, party, or cause.Given that the cost of voting is low and the probability of casting a decisive vote is close to zero, voters vote in ways that make them feel good.The payoff takes the form of psychological well-being.In this sense, voting is more like cheering for a football team.Despite not being able to influence the result of a game, one shows support for one's team.
Brennan and Lomasky contrast expressive voting with market behaviour.Market agents must decide on the basis of their material interests and are constrained by the direct costs and benefits of the price system.If such agents indulge in feel-good attitudes that are costly to their material interests, their private lives will suffer.In politics, by contrast, 'private interests in the electoral context will be heavily muted and the purely expressive or symbolic greatly magnified'. 57After all, one vote decides no major election.So, in terms of psychological benefits, it pays off to vote for our preferred cause without caring about how it affects our private interests.
A related model to the expressive voting model is Bryan Caplan's rational irrationality. 58The two models are similar, but there is a key difference.Expressive voting is agnostic about the content and patterns of people's beliefs.But Caplan adds that people tend to have systemic biases, which means they have inclinations to choose certain beliefs.He offers some examples of such systemic biases in politics: Anti-market bias -the tendency to undervalue the benefits of market mechanisms; Anti-foreign biasthe tendency to disregard the benefits of interacting with out-group members; or Makework bias -the tendency to underestimate the benefits of flexible employment and to think that a good economy is one that provides everybody with a steady job. 59ccording to Caplan, people not only have these biases, but they also tend to fight contrary evidence in order to keep their beliefs intact.In politics, it is easy to express these biases, especially as voters, because the beliefs of a single voter are unlikely to change society and thus have a detrimental impact on his or her life.Still, on aggregate, people can often choose bad policies.In Caplan's view, people do not simply vote for feel-good policies.They believe these policies to be beneficial for themselves -despite being ignorant about them -and get psychological benefits from voting for their biased views.
Caplan concludes that, in politics, it is often rational to cling on to irrational beliefs.Market mechanisms immediately punish individuals who engage in false beliefs, such as believing that certain products are better than they really are.But in politics, one may live a whole life believing in erroneous views without paying a high price for it.When irrationality is cheap and pleasureful, individuals will engage more in it.Still, despite their differences, both expressive voting and rational irrationality rely on the same logic of expressive behaviour.Namely, individuals balance the costs and benefits of their material and expressive utilities. 60The material kind represents people's material interests while the expressive kind typifies the expression of their beliefs or identity.

Expressive behaviour
Political theorists can apply the logic of expressive behaviour to all political behaviour, not only to elections. 61In politics, individuals may act instrumentally to achieve their material interests or expressively to feel pleasure when promoting cherished views.Of course, this dichotomy represents pure categories.In reality, most political decisions probably have mixed motivations.Individuals are likely to act at once for both expressive and instrumental reasons, acting more expressively or instrumentally according to incentives.For instance, a citizen may write a newspaper article advocating for a certain policy because he or she feels good when expressing such a view, but also to convince others to vote for that policy.Even the average voter may have some hopes of deciding an election, despite the low probabilities.As such, he or she is mainly an expressive voter but also an instrumental one.The context, in the end, determines whether actions are more expressive or instrumental.
But what are people expressing, then?Personal identity, claims Arye Hillman.He sees all expressive behaviour as 'the self-interested quest for utility through acts and declarations that confirm a person's identity'. 62He developed a model that investigates the trade-offs between the expression of personal identity and instrumental motivations in several contexts.As he notes, sometimes there are no conflicts between expressive and material utility.This happens when, for example, a high-income person who objects to welfare payments also gains expressive utility by promoting self-reliance.But some other times, expressive and instrumental utilities are at odds; for instance, when a person buys unusually expensive clothes because they signal that person's identity.Here, the expressive utility is higher than the material costs involved.
By focusing on identity, Hillman is treading close to ideology, which is a form of identity.One can identify as a conservative, socialist or liberal and attain meaning and purpose from those political outlooks.But ideology is a particular type of identity that requires its own analysis.Indeed, it is distinct from other types of identity such as ethnicity or gender -although these other types often inform ideologies.Furthermore, ideology is undertheorized from an expressive behaviour standpoint.

Ideology Elster's theory of ideology
There are, however, some influential RCT approaches to ideology.We wish to distinguish our proposal from them.Beyond the Downsian understanding of ideology as a coalitional device to cut information costs, a notable RCT view of ideology is Jon Elster's view. 63He offers a distinct reformulation of the Marxist theory of ideology.Despite not having defined ideology, Marx saw it as the production of images of social reality.These images represent ideas.And the ruling class promotes them to convince the lower classes to support a system that does not serve the lower classes' interests.In this Marxist sense, ideology is a set of false beliefs endorsed by the social superstructure and designed to create a false consciousness among the exploited.
Elster holds that Marx's theory is of great importance, although, in Elster's view, it requires methodological individualism to be robust.Elster also considers that false beliefs are not just the result of elite manipulation.Rather, it is often the subjects themselves who invent ideological (false) beliefs that are not in their true interest.They do so out of irrationality, which is caused by people's poor reasoning and widespread psychological biases.Ideological beliefs, then, flow from distorting processes like fallacies of inference or cognitive dissonance, wishful thinking or, more notably, the 'sour grapes' story.
There is no space here to depict the details of Elster's theory of ideology.It is worth, however, to describe the 'sour grapes' story, as it captures the essence of his theory.A hungry fox is incapable of reaching the grapes that hang above him, so he asserts that they are sour, although they are not.Instead of trying to find ways to eat the grapes, he changes his desire so that he feels better about that difficult situation, even if this requires developing false beliefs.The fox developed what Elster calls an adaptive preference, which is a 'desire that is adapted to what is available'. 64This is not mere stoicism -the rational decision to have aims that are within our reach.It is epistemic irrationality, because the fox must deem the grapes sour when there are no solid epistemic and causal reasons to do so.
For Elster, ideology stems from irrational biases such as the one from the 'sour grapes' story.In this sense, people tend to hold false ideological beliefs that are psychologically soothing.But these beliefs go against their true well-being and make them support oppressive social structures.Elster's theory aims at countering functionalist accounts of ideology.In his view, ideological beliefs do not serve any general function -like, for example, to oppress the lower classes.Rather, ideologies are products of poor reasoning and weakness of will.As a result, 'the oppressed believe in the superiority . . . of the ruler because (they believe) it is good for them', although to do so is also 'beneficial for the ruler'. 65ne can read Elster's psychological theory of ideology from an expressive behaviour standpoint; indeed, his view shares common ground with Caplan's rational irrationality model.Suppose people do ideologically think that oppressive systems are good for them despite having no sound epistemic reasons to do so.Caplan's model suggests that they behave as such because the benefits of being irrational are higher than the costs.Namely, the benefits of believing that one's own oppressive regime is benign outweigh the costs.If one cannot easily change the regime, and sees no prospects of that being possible, it pays off to think the regime is good.By doing so, one can gain psychological pleasure from such thoughts and increase life satisfaction.By contrast, if one thinks the regime is oppressive, one will suffer, especially because of one's impotence in changing the status quo.This situation is analogous to voting.From a rational irrationality standpoint, the voter also engages in feel-good irrational beliefs because of the low probability of deciding an election and because he or she sees no direct consequences of voting irrationally.

Ideology as a functional social technology
Our view of ideology differs from Elster's.We regard ideology as a functional phenomenon.We share the dominant view among evolutionary anthropologists that culture and morality are social technologies whose function is to facilitate cooperation among groups of individuals. 66Here, culture is a set of practices and beliefs, while morality is culture's normative dimension.Ideologies follow the same logic.They are political subcultures whose evolutionary function is to bind groups together around a set of beliefs.Ideologies help group members to cooperate with one another for common purposes and solve collective action problems.
Cultures and moralities are evolutionary strategies, which are adaptive when they help their groups to enhance reproductive fitness, but maladaptive when they decrease it. 67ia natural selection, fitness enhancing ideologies -and the people upholding themtend to survive and replicate more.As political subcultures, ideologies are fitness portfolios. 68They can make groups expand or dwindle, win or lose in competition with other groups, depending on whether ideological beliefs help their groups to gain economic power, attain sustainable lifestyles, win conflicts, etc.
Unlike Elster, we see ideology not as a product of innate psychological biases but of cultural evolution. 69Psychological biases can influence the production of culture, but they do not have the final word.Culture evolves faster than genes, 70 so most individuals have the capacity to adhere to new norms.Moreover, people can produce norms that may conflict with their biases.For instance, people may have biases against bitter herbs, but once it is known that some herbs have medicinal value, people still integrate them into their eating culture. 71In short, the rational mind is not the slave of biases.

Biases and ideology
Elster and Caplan overstate the importance of innate biases in the formation of ideology and political beliefs.Michael Rosen notes that Elster's theory fails to explain why people tend to irrationally accept social orders and ideologies that go against their (material) interests.In particular, Elster's theory cannot explain why psychological biases happen to be 'both misleading and conservative in its social consequences'. 72In our view, people accept the legitimacy of social orders and ideologies when they identify with the social group that such ideologies represent.Ideologies are, after all, coalitional mechanisms, as Downs saw it.They have a function.Ideologies act 'as labour-saving devices to enable individuals to identify their interests quickly whilst they get on with the business of living their own lives.'. 73In the absence of perfect information, it is often beneficial to adhere to those groups with whom one identifies, as they are more likely to have similar interests to oneself.This adherence does not have to derive from biases or weakness of will.
Elster sees ideological beliefs as entities that consciously exist in the minds of individuals.This view leads him to think that biases play a larger role in the formation of ideology than they do.Yet, as Keith Dowding notes, 74 beliefs do not exist in the mind only.And they do not exist consciously there.At a given moment, one is only aware of a few beliefs one has.Many beliefs that people hold are subconscious and people do not always examine them.Still, they continue to be people's beliefs.When individuals think about their ideologies, they may find contradictions and then adjust their beliefs.But, one should note, it is too costly to examine every subconscious belief.So, to cut costs, it is rational to use a rule of thumb such as 'adhere to the ideology of those you identify with'.
Caplan's rational irrationality model also overstates the irrational dimension of psychological biases in the formation of beliefs -biases such as anti-market, antiforeign and make-work.Although such biases do exist, it is well-documented that political partisans often lack robust or steady beliefs on essential political questions.Hence, they quickly change their beliefs in response to changes in elite or party messaging, 75 including beliefs about foreign policy and trade. 76In this light, group identity and interests usually underpin the contents of ideologies.'People tend to adopt beliefs, attitudes, and values that reinforce and rationalize their partisan loyalties'. 77This is consistent with a key insight of cultural evolution: groups change their cultural strategies rapidly to adapt to novel challenges. 78The rational irrationality model depends on people having innate and immutable biases.Yet, if this is not the case, most instances of rational irrationality are better seen as rational choices that express identity in a standard expressive behaviour model. 79In this light, our proposal applies the expressive behaviour model to ideology -which is a form of identity -and not to other forms of identity (as Hillman does) or voting (as Brennan and Lomasky do).

The RCT tension
How can we then combine ideology with narrow self-interest in RCT models?Notably, there is a tension between ideology and narrow self-interest because ideology can make people publicly interested (e.g.acting for the good of a certain disposition of society).In particular, the pursuit of ideology may imply that individuals act against their material self-interest.People may, for instance, vote for more economic equality, even though they know they will suffer from it. 80Given this, positive political theorists struggle to find the proper balance between ideology and narrow self-interest.Their most common solutions are to remove ideological behaviour from their models -as PCT scholars often do -or to see it as merely instrumental -as it happens in spatial election models.
PCT scholars, for instance, often rely on the assumption of material egoism, which does not account for the ideological motivation of individuals. 81These scholars assume that private interests drive political agents and that such agents are not motivated to act on the basis of public interest. 82ritics counter that political agents are less motivated by economic (self-) interest than agents in the marketplace, and claim that people in politics are instead influenced by ideology: There is the elementary fact that political decisions apply to the entire community.That they do so encourages people to think about others when taking a stand.This is in contrast to making personal decisions, when people think mainly of themselves. 83ere is abundant empirical evidence that displays the importance of ideology in influencing legislation. 84For instance, 'ideology is significant in explaining voting by congressmen on bills with primarily economic components'. 85PCT assumptions are challenged by many studies that show how people vote against their economic interest to support broad ideological concerns. 86espite the importance of ideology, models that remove ideological behaviour from their assumptions may still offer useful predictions and explanations in large and general contexts.Namely, in contexts where a strong reduction of complexity is required.But such models may often fail to offer meaningful explanations of phenomena in smaller political settings, like parliaments or parties, where ideology is central to understand political action.After all, most falsifications of material self-interest in behavioural economics come from small-scale lab experiments.It is thus advantageous to introduce ideology into RCT models, provided that they remain parsimonious and retain workability.Such a task is feasible.

Broad egoism and the primacy of material interests
Although public choice theorists often discard ideology, ideological concerns are consistent with PCT's assumption of narrow self-interest.To grasp why, we must consider that narrow self-interest can be split into material egoism and broad egoism.Given that material egoism excludes non-material motivations, it cannot include ideology as a behavioural driver.Ideological behaviour must then fall under the category of broad egoism, according to which individuals only undertake actions that directly improve their well-being.These actions can include ideological behaviour when it directly improves the psychic well-being of individuals.
If positive political theorists assume broad egoism rather than material egoism, the clear tension between ideology and narrow self-interest vanishes.Theorists can then explain, for example, why voters vote ideologically against their economic self-interest.They sometimes vote that way because it does not come at excessive cost to their material interests.Suppose John-the-voter is considering voting for expensive environmental legislation.He might be an environmentalist and could thus feel moral virtue when voting for it.Such a legislation may impose costs on him via taxes and higher prices, but he can ignore them because one's own vote will probably not decide a large-scale election.If John gets ideological satisfaction from voting 'yes', he might do so; even if the legislation hurts his economic interest. 87In this light, individuals vote ideologically because ideology is part of their utility function (part of their preferences).People might prefer a certain order of society, but this is just one preference among many other (narrowly self-interested) preferences.
Here, one could object that if we understand ideology as just part of people's utility function, we can justify anything that people do by saying they have a taste for doing it. 88et, the economic assumption that people distribute their limited resources over different actions to maximize their individual satisfaction counters this meaningless tautology.Neoclassical economic analysis tells us that when the cost of an activity goes up, people will engage in it less (and vice versa).When confronted with political choices, people may try to balance their ideology with their material interests.As illustrated above, they may vote for ideological reasons because it does not cost them much.Ideology works like any demand curve: greater costs result in less quantity demanded.This is how we can combine ideology with narrow self-interest: Ideology is just one preference among other (material) self-interested preferences.Politicians, for example, after coming to power, may moderate their ideology because they have to make it compatible with other (personal) interests, such as public influence and material goods. 89If ideology becomes too costly, it may need to be mitigated.
PCT scholars who deemphasize ideological behaviour in their theories argue that most interest groups organize around economic concerns.As Olson notes, 90 it is too costly for political agents to ignore private economic concerns for the sake of ideology.But PCT scholars do not have to exclude ideology from their models, since we should not confuse ideology with altruism.Following the assumption of narrow self-interest, people do not follow ideology regardless of the costs to other privately defined narrow interests.Rather, people engage in ideological activity only insofar as it advances or does not substantially harm their narrow self-interest, which is primarily materialistic.In this sense, people restrict ideological behaviour if it becomes too costly for their material interests.By assuming that material interests have priority over ideology, positive political theorists can introduce ideology as a motivational driver into their models and still uphold narrow self-interest.
In a way, spatial election models in the Downsian tradition already combine ideology with narrow self-interest. 91But this tradition understands ideology as a means to an end.Downs postulated that because of the high cost of acquiring information about party politics, voters use ideologies as a proxy to choose their preferred parties and thus their favourite policies. 92Our proposal differs from the Downsian tradition, for we consider that ideological behaviour is not merely instrumental.Rather, ideological behaviour can be a genuine driver of political action, yet one that is sensitive to personal material costs.Moreover, our proposal maintains that people desire certain policies for material reasons but also for ideological ones -they do not merely desire policies and use ideology to get them.Individuals, then, hold real beliefs about which policies promote the common good, and they pursue such policies.But when these beliefs clash with personal material interests, the latter prevail.So, while spatial Downsian models conclude that agents always pursue their narrowly defined interests under an ideological cover, our criterion holds that agents pursue true ideological beliefs but sets a limit to that pursuit.
In sum, Downs is partly right: ideology has the purpose of cutting information costs and binding groups together around their interests.If one's welfare depends on the welfare of one's group, we should expect political agents to act ideologically to some degree.Still, contra Downs, people are not necessarily cynical about their ideological beliefs.It is just that when the price of engaging in ideological beliefs goes up, people act less ideologically, and when the price goes down, people become more ideological.
However, sometimes (expressive) ideological beliefs trump (instrumental) material interests.As Hillman notes, when expressive utility 93 and material self-interest are in tension the latter does not always win.A person may, for example, 'forego income to live in a location for expressive reasons'; in this case, 'if material losses from the locational decision are high, expressive utility from the locational choice is higher'. 94An analogous example in politics could be a politician ideologically voting for free trade while foregoing income from protectionist local lobbies.Still, although people do often hold and pursue (expressive) ideological beliefs, material interests will tend to have primacy over ideology.

Justifying the primacy of material interests
The sceptic may insist that to choose the primacy of material interests over ideological concerns is an arbitrary choice.Why should we not assume that ideology is the primary motivation and that material interests are pursued as long as ideology is not sacrificed too much?Admittedly, sometimes ideology seems to take precedence over material selfinterest.For instance, in suicidal terrorist attacks, the terrorist self-sacrifices for ideological or political-religious aims. 95While these acts may be consistent with broad selfinterest, they appear incompatible with the primacy of material self-interest.Indeed, we should not expect someone who deliberately dies for ideological reasons to be pursuing earthly material goods, at least not for him or herself.In interviews, unsuccessful suicidal terrorists even rarely mention their intention to financially help their family; while they often mention their ideological cause and the will to help their group. 96uch radical acts, however, do not invalidate the assumption that people give primacy to material interests.Even most terrorists respond to survival and material incentives.Indeed, 'the typical member of a typical terrorist organization is fairly safe', 97 'faces risks no greater than those endured by most criminals or war-time soldiers', 98 earns above average income, 99 and receives social service provision from their terrorist group. 100oreover, suicidal terrorism is quite rare.'Terrorist movements are unusual to begin with, and the large majority of terrorist movements do not use suicide tactics'. 101As RCT is not a general theory of human behaviour, we may regard suicidal terrorist acts as unusual events that, overall, do not prevent models from reasonably achieving their aims. 102heorists should still assume the primacy of material concerns, for there is cause to think that this assumption has predictive and explanatory value.After all, political agents can achieve material satisfaction without caring about particular ideologies.And when they do care, they must have power over material resources to implement an ideology that satisfies their ideological preferences.Only with authority over resources can one decisively shape society in a particular direction.Yet, political agents who prioritize ideology over material interests may never fulfil their ideological desires.Such agents would probably be too inflexible to deal with the necessary trade-offs to achieve and maintain power positions. 103They are more likely to get substantial ideological satisfaction by giving primacy to material interests, such as power, wealth, status, etc.
Ultimately, from an evolutionary standpoint, the competition for resources is a key factor in shaping human (and non-human) evolution -especially when resources are scarce. 104While the coexistence of different social groups is possible, it requires reproductive growth strategies that rely on different quantities and types of resources. 105As human groups often compete against groups that have similar growth strategies, conflicts over scarce resources arise.And because better resources aid reproductive success, natural selection should favour individuals who are concerned about acquiring material goods, regardless of their current ideology.This is not to say that ideological concerns have little impact on political behaviour.Rather, they are important as long as they do not prevent political agents from achieving power over material resources.In fact, ideological concerns are crucial when they help political agents to achieve wealth and influence.Upholding an ideology, for instance, can help politicians to get elected or receive public support.By achieving political power, such agents may still implement parts of their ideology, but without political influence, they cannot implement any view.We should then expect political agents to give primacy to material interests, for the payoffs are higher, even if we measure them in terms of ideological satisfaction.

Conclusion
In this article, we advanced a general criterion to combine ideology with narrow selfinterest in positive political theory.First, we defended the assumption of narrow selfinterest.Then, we explained how positive political theorists may integrate ideology into that assumption.We suggested that ideology drives political agents until it imposes considerable costs on their material interests.Overall, while the inclusion of ideology as a behavioural driver can improve RCT models of politics, positive political theory would gain from prioritizing material interests over ideology.