Belief in spirit (sometimes called demons, loa, vodoun or ghosts) seems marginal or nearly absent in contemporary philosophy and wider academia. It is far from that beyond those realms. Spirits are highly prominent in most religious traditions (see below) and in many people’s lives.
Spirits are generally regarded as supernatural beings. They have powers beyond those of humans, like the ability to be invisible or to take on different shapes. Some can appear and disappear suddenly or travel at great speed. Unlike God, spirits are not attributed omni-properties or other perfections. They also had no role in creating the universe, but are part and parcel of the created universe.
Belief in spirits is widespread across the globe. Many Christians (both historically and contemporary) believe in the existence of demons. Christians tend to see demons as malevolent beings that pull people into sin and are therefore best avoided. Many Christians also believe in angels, celestial beings of a morally good nature who live in close relation to God. Judaism has similar beliefs in demons and angels. More than in Christianity, Jewish sources include elaborate discussions on the names and natures of various demons and angels. Muslims hold similar beliefs on angels. Many also hold beliefs regarding Jinn, a class of beings created from fire. A large number of Hindus and Buddhists hold beliefs in various beings that can be counted among the spirits. These include Yaksha and deva’s.
Spirit beliefs feature prominently in most smaller religions as well. Adherents of Shinto worship Kami, spirits which are often tied to natural phenomena like rivers or mountains. Chinese indigenous religion includes veneration of shen and ancestor spirits. Afro-Caribbean religions (e.g. Vodou, Santeria and Candomblé) have elaborate rituals revolving around spirits (called loa’s or orisha’s). More than other traditions, Afro-Caribbean religious practices often revolve around spirit-possession, where a spirit temporarily takes over a human’s body and functions. The African traditions from which Afro-Caribbean religions derived have similar practices.
Philosophy of religion has a venerable tradition of arguments for the existence of God. Another common topic is the epistemic status of belief in God. Various defenses of the justification of belief in God were put forward. The best-known are Alvin Plantinga’s Reformed Epistemology (Plantinga 2000), William Alston’s defense of Christian mystical practices (Alston 1993) and defenses of the epistemic import of religious experiences (e.g. Swinburne 2004: chapter 13).
Apart from a few exceptions, these lines of argumentation have not been applied to spirits. Philosophy of religion and most contemporary theology displays a deafening silence on spirits. Few handbooks and very few recent publications discuss the issue. Reading antique and medieval sources reveals a very different picture. Most philosophical heavyweights, including Plato, Augustine, Thomas Aquinas and Friedrich von Schelling did spend considerable time discussing spirits and their natures. The lack of attention to spirits is likely due to a certain awkwardness. Many contemporary religious thinkers seem to regard belief in spirits as a remnant of backward ontologies and ways of thinking that have no place in a contemporary worldview.
The lack of discussion on spirits may lead one to think that belief in spirits is hopelessly irrational and unjustified. Some uneducated or neo-pagans may still hold beliefs, but no serious, educated person can take them seriously anymore. Such a claim is, however, problematic. Arguments against the existence of spirits are rather scarce. Furthermore, few scholars have made the case why belief in God is justified whereas belief in spirits is not. Also, the apparent anti-spirit consensus in academia does not have much evidential value since the epistemic status of beliefs is not decided by counting noses.
One underexplored way to argue for justified belief in spirits takes its cue from phenomenal conservatism (cf. Huemer 2007). Defenders of phenomenal conservatism argue that experiences lend justification for beliefs in the absence of defeaters. Those that applied phenomenal conservatism to religious experience usually argue that experiences of God can justify belief in God (in the absence of defeaters), or enjoy an ‘innocent-until-proven-guilty-status’. When a subject has an experience of God, she is justified in believing that God exists. She is also justified in holding beliefs regarding God’s nature if God is experienced as having that nature.
Applying phenomenal conservatism to spirits is not much different than to experiences of God. All over the world, people report experiences of spirits. Take the following example:
I dreamed an old woman, a white woman, very old—very, very, very old. The old lady called out: ‘Philo! Vin pale ou [Come talk to me].’ She asked me: ‘You are pregnant?’ And I put my head down … because I was ashamed … and I said to her. ‘Yes, I am pregnant/The old lady asked me: ‘Why do you drink things to put that baby down? Why do you do that? That baby is going to be born, and that baby is going to be a girl.’ ‘How do you know?’ I asked. She said, ‘I know.’ Then the old lady said to me: ‘Stop what you are doing. Don’t take anything more. I will support you. I will give you everything. M’ap ba ou bwe; m’ap ba ou manje [I’ll give you drink; I’ll give you food].’ And I said, ‘How are you going to do that?’ And the old lady just turned and walked away. (Brown 2010: 209-210)
The example reports of an experience of Vodou loa Ezili by an adherent of Haitian Vodou. The subject reports an experience similar to a visual perception wherein Ezili delivers a message regarding an unborn baby. If taken at face value, the experience can justify belief that Ezili exists and takes an interest in the experiencer. Other beliefs regarding the nature of Ezili could also be justified.
Is there any reason to drive a wedge between experiences of spirits and experiences of God? For adherents of phenomenal conservatism, there appears not, at least prima facie. Both beings (spirits and God) are experienced by subjects and hence believing they exist enjoys some level of justification. Differences can arise concerning ultima facie justification when potential defeaters are taken into account. I turn to this next.
Many people in the West seem convinced that experiences of spirits are hallucinations or can easily be explained away as figments of the imagination. Very often the argument is left undeveloped. Merely calling an experience of a spirit a hallucination is not very informative since hallucinations are defined as non veridical experiences. Some work in cognitive neuroscience could inform a defeater. I give some examples and argue why they are unconvincing.
A first defeater attributes spirit experiences to a mind that is overly detective towards detecting agency. For evolutionary reasons, it is beneficial to quickly jump to the conclusion that some being is around. Not doing so could mean instant death. As a result, humans are very quickly prone to see agents everywhere, even upon very limited evidence. Vague noises or patterns may suffice. When no visible agent is to be found, it could easily raise the sense that some invisible agent is around. This can foster belief in spirits.
Does the theory work as a defeater? It might knock out vague experiences that pass quickly. It, however, does not account for longer, stable experiences like the one in the example of Ezili above. The report does not resemble an experience triggered by a vague noise or pattern where the human mind quickly and erroneously concludes to invisible agency. The experience is much more calm and laden with visual images. Given that other experiences are often more like the one in the example than quick, fleeting experiences, questions can be raised regarding the scope of the theory as a defeater.
Another theory that got a lot of attention attributes experiences of a sensed presence to micro-seizures in the temporal lobe. Michael Persinger claims that micro-seizures caused by changes in electro-magnetic variation can trigger experiences that some invisible presence is near. He argues that this can account for experiences of spirits and God (M. Persinger 1985). Persinger even claims he can artificially create such experiences by means of a helmet that triggers micro-seizures (M. A. Persinger and Healey 2002).
Problems arise for this defeater as well. Persinger’s theory and claims concerning the helmet have been fiercely criticized (e.g.: Granqvist et al. 2005). It is also unclear whether micro-seizures can explain longer, sustained spirit-experiences like the one in the example of Ezili. Therefore, this defeater does little damage as well.
Other defeaters for spirit experiences can be defended. Until a convincing one is found, it appears as if spirit experiences can enjoy an innocent-until-proven-guilty-status and justify spirit beliefs.