Political corruption is a universal phenomenon which, even though the times, ideas, laws and cultures of different countries have evolved, has remained unchanged since ancient times [
1]. As long as we can remember, political corruption has accompanied the evolution of human kind through its different cultural stages or civilizations. Early referrals to the concept date back to the Pharaonic Egypt period [
2], with later evidence indicating that Roman politics hit the bottom due to its corruption in the Republic times of Roman civilization (70 and 50 BC), and as a result the legal code “Twelve Tables” [
3] being passed, which imposed the death penalty on judges who accepted bribes and politicians who attempted to influence election results through bribery or other forms of “soft power”. This concept lies in the ability to shape others’ preferences based on culture and intangible assets, such as the credibility and trustworthy of individuals and institutions [
4].
Political corruption decelerates social growth and economic activity [
14,
15], diverts resources from basic services [
16], reduces innovation [
17] and, consequently, also the introduction of new products and technologies because innovators and entrepreneurs usually lack political connection [
18]. In general, foreign direct investments decrease [
19,
20,
21], and national firms’ value drops [
22,
23,
24,
25]. Thus, industry must pay more to lenders given the perceived political instability impacting the credit market [
26,
27,
28]. At those countries where the state institutions are weaker, corruption is often linked to violence, whereas in the so called mature democracies, corruption means the increase of economic and social insecurity and also the opportunity for the privilege to get richer at the expense of everyone else [
29]
Hence, literature has analyzed the types of political corruption, its causes or consequences from a theoretical perspective or even empirically focusing on indicators built using historical information. This work means a contribution to the literature and bridges the gap in the literature by: (i) mathematical modeling the political corruption in a free market economy in which democracy does not serve as a warranty of policy making responds to the public interest and (ii) quantifying the total population at risk of committing political corruption. Following, the study identifies the drivers of the problem and highlights the main novelties of the research in terms of methodology employed, data and its contributions.
1.1. Political Corruption in Spain
Even though political corruption is a cross-country reality, its level of intensity and the manner of its effect vary from one nation to another [
18]. In this way, [
30] since 1995 CPI 2020 has annually issued the corruption perception index to measure from 0 to 100 the perceived level of corruption in the public sector worldwide in accordance with businesspeople and experts. It has become the leading global indicator of public sector corruption. Hence, [
30] CPI argues that public sector transparency is the key to ensure public resources being appropriately spent. However, the 2020 annual report shows that more than two thirds of 180 countries score below 50. In particular, Spain ranked 32 worldwide with 63 points, while Western Europe and the European Union scored 66 on average. Denmark had the highest score with 88 points, and Romania the lowest with 44 [
30,
31,
32].
Thus, identifying the factors that explain political corruption is essential for understanding the trends and differences of this phenomenon among countries. The factors explaining the persistence of political corruption in Spain are discussed below in accordance with previous research [
33]. Culture, and particularly religion [
34], explain why corruption rates are higher in south than in northern Europe. In Latin America, the culture of the former was inherited from Spanish and Portuguese cultures.
Second, political corruption is explained by the nature of the Spanish political party system and the Parties’ Law that guarantees continuity of the establishment [
35,
36]. In relation to the laws regulating the parties, there is the opacity of financing political parties, which are not obliged to publish their financial information [
37]. Indeed, Spain does not enforce political parties disclosing their financial information or candidate funding in their reports, while 93% of OECD countries do [
38], even though institutionalized transparency and accountability are the main aspects that promote the integrity and fairness of public decision making [
39]. This situation is connected to previous scandals of political corruption that have affected the two longest-standing parties: PP (right-wing) and PSOE (left-wing) [
40,
41], which resulted in the end of a two-party system [
42,
43], and in the appearance of new political parties during general and local elections campaigning with vows to get rid of what they brand a “corrupt political elite”. However, the most vindictive of these emergent accuser parties has also been prosecuted by irregular financing [
44], and thus perpetuates the same phenomenon: political corruption in Spain.
Thus, analyzing the functioning and structure of Spanish political parties would evidence the fulltime politicians whose professional career involves occupying a seat at office for the long term, but lack experience in the wider world [
45,
46]. This fact fosters patronage as an expression of political corruption; that is, recruiting public sector employees based on political connections rather than on their skills and formal qualifications [
47]. Indeed, merit-based bureaucracy, as opposed to one in which politicians appoint employees at will, is expected to reduce corruption [
48].
However, on the aforementioned factor, an important connotation is found in gender terms given the systematic differences in how men and women perceive corruption [
49,
50]. Several studies have empirically evidenced a negative relation between women’s presence in politics and its effect on corruption [
51,
52]. This can be explained by different gender behavior as women are generally more collaborative than men, but also more altruistic and ready to engage in “helping” behavior [
53,
54]. Moreover, in accordance with [
51], political corruption is a deterrent to women’s representation because it reinforces “clientelist” networks that privilege men.
In order to commit any crime, two conditions are needed simultaneously [
55], sufficient aggressiveness to dare and moral disconnection to bear the thought of our conscience. The evolution of the species [
56] has developed a distribution of social roles and habits, which are transmitted genetically, in which males have primarily devoted themselves to tasks related to aggressiveness and are more trained and accustomed, such as counterfeiting, big animals, defense of the territory and war. These social habits make men, in general, more aggressive than women, and for this reason, more prone to commit any crime, and in particular for political corruption. This aggressive training of men makes them have less social shame than women, men care less than women about being discovered in crime. From this, it follows that, at least for a long time, women are less at risk of committing corruption. This implies promoting the presence of women in politics and, consequently, in office as a tool to fight corruption. Moreover, Ref. [
57] argues that the longer women remain in office, the lower the corruption levels are, which contrasts with how men in office impact political corruption.
The next factor that aggravates the situation is highly politicized Spanish media [
58,
59] based on ideological alignments; as Refs. [
60,
61] argue, presently the media’s role does not involve promoting knowledge and defending public interest, but is instead a strategy for political action. In fact, in an attempt to control journalism and the media, political parties run communication and news offices. Indeed, Spanish politicians calling press conferences without allowing questions, and refusing camera operators and reporters admission to election campaigns, have become common practices [
62].
The last relevant factor to correlate with political corruption is lack of independence among judiciary, executive and legislative powers. Judiciary Councils are institutions created to protect judges’ autonomy. However, according to [
63], 36% of Spanish judges perceive their Judiciary Council as not respectful of their independence. This rate was the worst result of the survey carried out by European Network of Judiciary Councils during the 2014–2015 period. This situation is explained by the politicization of the General Council of the Judicial power reported by Nieto [
64], which means that the political parties in office control the nomination of the candidates appointed by the parliament.
Thus, imperfect judicial and media independence does not favor the end of the problem [
65,
66], and even less so when political parties are unable to make decisions against their partisan interests, even when these decisions are for the good of Spanish society and the country’s socio-economic future. Likewise, an intoxicating and generalized state of moral relaxation has been established in Spanish society, which excuses the political corruption phenomenon as being inevitable and inherent to the political class and is, therefore, irremediable. Not only does this not slow the problem down, it perpetuates it and amplifies its dimension [
55,
67], which indiscriminately affects all social chain links [
68].
The effect of Spanish political corruption is corrosive because it deteriorates the country’s image: economy drops, especially for a country like Spain that is so dependent on tourism [
69], with citizens mistrusting the national institution [
70], which affects foreign investors and citizens’ quality of life, and makes the country’s future worse [
71,
72]. Lack of trust in institutions generates moral disengagement, which makes it easier for citizens to excuse the political class’s corruption, who consider it alien, but use it at the same time as an excuse to commit themselves [
55]. This kind of contagion is very counterproductive given its social, economic and moral impact on society [
73].
The most important factors to explain the current situation are the party system and its laws, where political offices do not respond to citizens, but to the political leader who has appointed them, and where lack of self-criticism, transparency and accountability come into play.
1.2. Novelties of the Study and the Paper’s Structure
The demonstrated cases of political corruption that have been echoed by the media in recent years for their economic, judicial and social significance are merely the tip of the iceberg of a problem hidden by many interested parties, and also due to the shortage of the means to fight it. Particularly for Spain, and in accordance with [
69,
74], political corruption emerged (more than 200 reported cases) during the economic boom between 2000 and 2011, while almost no local corruption was previously registered.
In this work, we quantify the level of risk of committing political corruption for the population living in Spain aged between 16 and 70 years old. Individual behavior is unpredictable, but aggregate behavior can be predicted by mimetic contagious and herding human behavior [
75,
76,
77,
78]. According to [
67], humans are driven by emotions. Unlike previous studies that have centered on political corruption [
79,
80], we managed a political corruption concept that is not only limited to individuals in the political scenario, but also embraces the rest of the population.
This study is a novel contribution to the literature and bridges the gap in the literature about modeling and quantifying the total population of Spain in accordance with its risk of committing political corruption. It also identifies four levels of risk of committing political corruption. Apart from classifying the population according to their level of risk of committing political corruption, this study also takes into account their employment situation at the time the analysis was carried out.
Our model allowed us to predict the risk of political corruption in Spain given the mimetic nature of humans by constructing a discrete finite epidemiological model [
81] that classifies and quantifies citizenship in Spain into subpopulations according to their risk of committing political corruption. Despite previous theoretical approaches to the problem that focus on diagnosing the causes or processes of political corruption cases [
82,
83], our model is dynamic and classifies the population on an annual basis according to their level of risk of committing political corruption over time during the 2015–2023 period [
35,
84,
85,
86].
Previous studies have employed surveys or historical statistical data to quantify the corruption perceived by different stakeholders at cross-country, national or local levels by building indicators or regression models [
6,
42,
87,
88]. In contrast, we study subpopulation trends during the study period by quantifying the annual dynamic transits among subpopulations. These transits are produced by an individual’s occupational status at the time the analysis was performed, combined with the following external variables that were quantified for each period: elections, time in office, gender, moral disconnection, economy, religion and the “revolving doors” effect [
89]. This effect is the transfer of professionals from the government and public administrations to private companies or social entities, which leads to conflicts of interest and the possibility of corruption [
90].
Thus, at each given time point, we quantified the number of individuals by their risk of committing political corruption in Spain. To the best of our knowledge, this is the first study to dynamically score political corruption by levels and sizes in a given country. The relevance of this study lies in reporting the problem to the public authorities responsible for addressing policies to stop this trend.
This article is arranged as follows:
Section 2 describes the hypotheses and methodology.
Section 3 presents the model construction.
Section 4 shows the results and simulations.
Section 5 offers the discussion of the results and conclusions.