The first step here is to examine whether the dataset follows a normal distribution, the results of which are given in
Table 2 for the EPI and in
Table 3 for the DI. These tables present the estimates obtained and the estimated probability (denoted as a
p-value) concerning the null hypothesis. Typically, a small value of the estimated probability (typically ≤0.05) indicates strong evidence against the null hypothesis [
69]. Consequently, in such a case, we can reject the normality assumption and argue that there is evidence that the data tested are not from a normally distributed population. Specifically, the normality hypothesis, concerning EPI data, is rejected for 2006, 2008, and 2014, but cannot be ruled out for 2010 and 2012.
In order to assess the possibility of synchronized variables, two steps were followed sequentially. Firstly, it was considered whether a statistically significant relationship between these variables exists. This can be done by comparing the value of an estimate with the critical value of the specific test. If the (correlation coefficient) estimate exceeds the critical value, the relationship is statistically significant, and vice versa. A typical source of critical values for Spearman’s test is Reference [
78] (p. 962). Secondly, the strength of the likely association between the examined variables was determined by comparing the absolute value of the estimate with the pre-specified standards. In social sciences, these standards which can be used to assess the evidence of data synchronization are the following: a very strong correlation (0.7–1), a strong correlation (0.5–0.7), a moderate correlation (0.3–0.5), a weak correlation (0.1–0.3), and no correlation (0–0.1).
4.1. Gaining a More Nuanced Picture by Breaking down Democracy into More Factors
The paper holds that, when it comes to exploring the relationship between democracy and the environment, the devil is in the detail. As Acemoglu et al. [
79] argue, it may be the role of omitted variables that inflate the association between environment and democracy. In order to shed some light on this controversial issue, we stratify the dataset on the basis of some institutional and economic criteria, as follows:
- a)
Government effectiveness (GE) drawn from the Worldwide Governance Indicators (WGI);
- b)
Countries’ classification by income proposed by the World Bank;
- c)
Corruption Perception Index (CPI) taken from Transparency International (TI).
In doing this, it is possible to examine whether these variables (government effectiveness, economic prosperity, and corruption perceptions) affect the association between democracy and environmental quality. The choice of the previous variables was based on compelling arguments in the scholarly literature [
7,
80].
The GE index represents one of the six aspects of governance monitored by the World Bank in order to release the WGI The effectiveness of governance primarily refers to the quality of policy formulation and implementation, and the credibility of the government’s commitment to these policies. The WGI indicators are based on several hundred variables collected from 31 different data sources, capturing people’s perceptions of governance as reported by survey respondents, non-governmental organizations (NGOs), commercial business information providers, and public sector organizations globally [
81]. The values of GE were normalized and the whole sample was stratified into four groups. These were (a) low government effectiveness (score 0–0.25), (b) moderate government effectiveness (score 0.26–0.5), (c) high government effectiveness (score 0.51–0.75), and (d) very high government effectiveness (score 0.76–1).
Table 5 presents the correlation coefficients disaggregated by Government effectiveness groups.
Table 5 reveals an interesting set of results. Firstly, when government effectiveness is low, then there is no statistically significant relationship between democracy and environmental quality. Some examples of countries which belong to this group are Afghanistan, Togo, Sudan, and Zimbabwe. Secondly, as government effectiveness increases, there is evidence of a weak association between democracy and environmental quality, albeit not always statistically significant. Examples of countries that fall within this group are Zambia, Nepal, Morocco, and Ecuador. Under high government effectiveness, the evidence reflects a statistically significant association between environmental quality and democracy. However, the strength of this association is not consistent through time. It is mostly weak for 2008, 2012, and 2014, moderate for 2010, and strong for 2006. Some examples from this group are Greece, Poland, Spain, Uruguay, and Jamaica. Finally, when government effectiveness is very high, there is evidence of a mostly weak link between democracy and environmental quality, although not always statistically significant. Examples from this group are Australia, Germany, Finland, and Canada.
Similarly, mixed results concerning the role of government effectiveness on environmental quality were previously reported in the scholarly literature [
82]. Some researchers argue that government effectiveness, broadly defined as the capacity of state institutions to implement legitimate objectives effectively, seems to decline in young democracies [
83]. Likewise, Bäck and Hadenius [
84] argue that the relationship between democracy and government effectiveness is not monotonic and depends upon the level of democracy. Furthermore, in authoritarian states, there is a negative relationship between government effectiveness and environmental quality, while at the same time environmental protection increases with higher government effectiveness [
85].
The results presented in
Table 5 suggest a complex association between democracy, environmental quality, and government effectiveness. Only when there is high government effectiveness (GE score 0.5–0.75) can we affirm a clear and mostly weak association between democracy and environmental quality. Such an observation may imply that high government effectiveness in designing and enforcing policies for environmental protection seems to be among the necessary prerequisites for a democratic regime to mobilize these social processes that are beneficial for the environment. In all other cases, there are either non-existent links (statistically insignificant) or mixed evidence (co-existence of significant and non-significant results). By reversing the previous argument, one may try to explain the cases of low and moderate government effectiveness. In these cases where governments are ineffective at applying policies for environmental protection, democracy’s role may be restricted. In stark contrast, when governments are very highly effective, probably the role of democracy is already accomplished. Nevertheless, Mol [
86] is rather skeptical with the notion that associates state capacity and power with environmental protection. Above and beyond that, another plausible explanation may concern the quality of the data used. In particular, WGI data were severely criticized as being the product of “a complex atheoretical and poorly articulated hypothesis” [
87].
Table 6 depicts the association between the EPI and the DI split by the World Bank classification by income for brevity and simplicity, the lower–middle-income and the upper–middle-income groups were joined together under the label of middle income. This is a standard aggregation in the literature [
88].
The conclusion to be drawn from this analysis is that the role of democracy is nonexistent for low-income countries since no statistically significant link exists between the EPI and the DI (
Table 6). Such a link is statistically significant for middle-income countries (weak to moderate) and for high-income countries (moderate to strong). Judging from the strength of this link, it can be argued that democracy is probably good for the environment for rich countries, while there is evidence of a weak link for middle-income countries. Such a result supports the assertion made in Reference [
42] where it is impossible to assess the implication of freedoms on environmental quality independent of incomes. A plausible explanation may be that a rich country, compared to a poor one, is more likely to acknowledge and embrace post-materialist values. The presence of these values can predict pro-environmental attitudes [
88]. In turn, it is possible that these attitudes could be mobilized toward societal goals that include environmental protection.
Li and Reuveny [
8] found that democracies have a positive effect on income distribution; however, Ravallion et al. [
89] claim that the impact of income inequality on environmental degradation depends on the marginal propensity to emit (MPE). If the poor have a higher MPE than the rich, reducing income inequality will increase emissions of pollution; if they have lower MPE, then the reduction of inequality reduces the pollution. It means that more variables broaden the view on the democracy/income and environmental concerns.
Finally,
Table 7 displays the association between the EPI and the DI split by the CPI scores. The CPI ranges from 0 (high corruption) to 100 (absence of corruption). As in the case of government effectiveness, four groups were created: (a) seriously corrupted (score 0–25); (b) moderately corrupted (score 26–50); (c) clean (score 51–75); and (d) very clean (score 76–100).
Table 7 shows that the positive association between EPI and DI is statistically significant only for the third group, i.e., the clean countries classified on the CPI score. The exception of the second group in 2006 is ignored on the basis that there is no statistically significant relationship in all other years; it must be a data problem. The third group is the most populated one and comprises all the relatively clean countries. Some examples are the United States of America (USA), France, Cyprus, and Malta. However, judging by the strength of such an association between EPI and DI, it can be argued that, although this is a statistically valid relationship, it is quite weak. While it is generally accepted that the control of corruption is a clear and direct determinant of environmental quality [
90], there is no consensus about its indirect impact through a democratization process. For example, Morse [
91] provides evidence of a positive link between corruption and environmental sustainability; however, at the same time, he also gives a clear warning about aggregate measures of preferences and perceptions as the CPI. By contrast, Povitkina [
20] argues that corruption undermines the function of democracy and, consequently, corrupted countries cannot exploit the well-known advantage of democratic regimes to improve environmental quality. Welsh [
92] argues that the effect of corruption on environmental quality is not monotonic. Only for low-income countries may controlling corruption improve environmental quality [
92].
A similar line of reasoning as in the case of government effectiveness can be put forward here. Specifically, if a country is corrupted, or perceived as such, the democratic institutions are likely to be thin and ineffective to contribute toward environmental quality (see countries such as Yemen, Kenya, or Mexico). On the contrary, a very clean government, such as that in Switzerland, Sweden, Finland, or New Zealand, is most likely to be in a full democratic state where the regime’s nature already capitalized on the quality of the environment.