Although Lankford (Reference Lankford2013c) is primarily focused on the important psychological similarities between suicidal individuals and suicide terrorists, he also notes one important difference: they are morally evaluated in divergent ways. In particular, Lankford notes that millions of people worldwide believe that suicide terrorism is sometimes justified (see also Atran Reference Atran2003; Ginges et al. Reference Ginges, Hansen and Norenzayan2009). This contrasts sharply with the strong prohibitions that are often leveraged against “conventional” forms of suicide, particularly in Islamic countries. Because suicide terrorism is often celebrated rather than condemned, it potentially manifests as a more socially and religiously acceptable alternative means for suicidal Muslims to kill themselves – a “way out” of the stigma associated with conventional suicide (Lankford Reference Lankford2013c).

In this commentary, we argue that Lankford is correct to identify conventional suicide as marked by a distinctive stigma. In addition, we go beyond this claim to elucidate the nature of this stigma, showing that it stems from deep-seated psychological roots rather than mere cultural proscriptions. We point to a large body of research demonstrating that moral beliefs are deeply informed by evolutionarily shaped intuitions (e.g., Haidt Reference Haidt2012), which largely operate independently of religious beliefs (Bloom Reference Bloom2012). Given that harsh condemnations of suicide have persisted across cultures and throughout history (Durkheim Reference Durkheim, Spaulding and Simpson1897/1979; Gallup Reference Gallup1978; Joiner Reference Joiner2010), there is reason to believe that negative moral evaluations of suicide arise independently of codified scriptural laws.

Our elucidation of the cognitive basis of suicide blame is informed by Moral Foundations Theory (Graham et al. Reference Graham, Nosek, Haidt, Iyer, Koleva and Ditto2011; Haidt Reference Haidt2012), which identifies a plurality of natural psychological systems from which moral judgments emerge. Although proscriptions against harm are the most prototypical moral concerns (Gray et al. Reference Gray, Young and Waytz2012), they cannot account for the full range of the moral domain. For example, certain harmless actions (e.g., atheism; eating a dead dog; same-sex marriage) are denounced because they are deemed defiling and impure (Brandt & Reyna Reference Brandt and Reyna2011; Haidt et al. Reference Haidt, Koller and Dias1993; Koleva et al. Reference Koleva, Graham, Iyer, Ditto and Haidt2012). These purity-based moral judgments involve neural, emotional, and computational signatures that are qualitatively distinct from those underlying harm-based evaluations (Parkinson et al. Reference Parkinson, Sinnott-Armstrong, Koralus, Mendelovici, McGeer and Wheatley2011; Rozin et al. Reference Rozin, Lowery, Imada and Haidt1999; Young & Saxe Reference Young and Saxe2011). For example, moral judgments about purity issues are closely associated with the emotional reaction of disgust, while moral judgments about harm issues are closely associated with anger (Rozin et al. Reference Rozin, Lowery, Imada and Haidt1999; Russell et al. Reference Russell, Piazza and Giner-Sorolla2013; Seidel & Prinz Reference Seidel and Prinz2013).

The identification of the basic moral foundations of harm and purity suggests that even when suicide terrorism is condemned rather than praised, it will never be denounced in the same way as conventional suicide. In particular, while suicide terrorism is considered immoral because of the harm it causes, our recent research demonstrates that conventional suicide is (perhaps surprisingly) considered immoral because of purity-based concerns. Specifically, regression analyses conducted on participants' evaluations of a series of obituaries – rated according to how morally wrong each death was, how angry it made them feel, how disgusted it made them feel, how much harm had been done, and how impure the victim became – demonstrated that individual differences in the moral condemnation of suicide were predicted by ratings of disgust and impurity rather than anger and harm. When we ran the same regression analyses on homicide obituaries, we instead found that harsher moral judgments were predicted by ratings of harm. Our finding that suicide is a purity-based concern has been replicated several times, and this result holds true even among participants who are non-religious and politically liberal, suggesting that beliefs about the wrongness of suicide are cognitively natural rather than culturally instilled (Rottman et al. Reference Rottman, Kelemen and Young2014; in press).

The distinctive purity-based nature of suicide blame and its accompanying disgust reaction have important implications. In particular, the condemnation of suicide is likely to be enduring and linked to negative assessments of the suicidal person's character (Russell & Giner-Sorolla Reference Russell and Giner-Sorolla2011), as well as perhaps leading to extreme dehumanization (Harris & Fiske Reference Harris and Fiske2006; Haslam Reference Haslam2006). This contrasts with moral judgments of suicide terrorism, for which the locus of condemnation is the harmful act rather than an individual's nature, and which produces the shorter-lived emotion of anger (Giner-Sorolla & Maitner Reference Giner-Sorolla and Maitner2013; Skitka et al. Reference Skitka, Bauman and Mullen2004). In addition, given that people have strong natural intuitions that the self is fundamentally comprised of a soul that persists beyond death (Bering Reference Bering2011; Bloom Reference Bloom2004; see also Emmons & Kelemen, in press), the belief that a suicide victim defiles his very essence in perpetuity is no small matter.

Based on the discrepant moral evaluations of suicide and suicide terrorism, Lankford (Reference Lankford2010; Reference Lankford2013c) suggests that “martyrdom” could be made more disgraceful by exposing potential suicide terrorists as deserving the stigmatization of conventional suicide. Although we appreciate that this recommendation could plausibly help to deter potential suicide terrorists, we close with a note of concern about this normative advice. Publicly denigrating potential suicide terrorists for being suicidal would likely exacerbate the purity-based stigma against non-murderous suicidal individuals, as well as worsening the already intensified and complex grieving process for those who have lost loved ones due to suicide. Because of the disproportionately greater number of deaths caused by conventional suicides as compared to suicide terrorism, this would be a concerning outcome. If suicide terrorists are truly suicidal, as Lankford claims, then a much more productive solution would be to increasingly provide helpful resources for individuals at risk for suicide.