An Introduction to Philosophy of Religion
Is it reasonable for intelligent and educated people in our times to endorse a religious belief that a particular god exists? Some of you may nod and point to the many positive aspects of doing so, such as emotional satisfaction, helping the poor, or constructing a coherent community of believers, who often assist each other affectionately. Others might protest by mentioning more problematic features, like religiously motivated devastating deeds.
For example, on 7 January 2015 two Islamist brothers Kouachi entered the offices of the French satirical journal Charlie Hebdo in Paris, armed with guns and other weapons. Shouting “Allahu Akbar!” they killed twelve people and injured eleven. The main motive for this massacre was a religious one: to punish journalists for their jocular depictions of prophet Muhammad. Some Muslims praised the Kouachi’s as heroes of Islam, but most Islamic organizations condemned their actions as anti-Islamic. Clearly, endorsing a specific religious belief may have positive but also evil impacts.
Philosophers of religion raise and try to answer many different questions about religion(s). An important set of such questions is concerned with religious beliefs: what exactly are they about, and can holding them be considered reasonable or legitimate in some sense? If we want to investigate the reasonableness of religious beliefs, we have to start by making some conceptual distinctions.
First, the word ‘belief’ may be used in two different ways. On the one hand, when a belief is called courageous, tentative, firm, or cowardly, we refer to someone’s believing something, that is, to an aspect of one’s mental life. On the other hand, if we call a belief true, false, likely, or improbable, we focus on its propositional content, that is, on what is believed. Whenever we discuss the legal legitimacy of endorsing religious beliefs, or when we practise the social sciences of religion, we zoom in on the former feature, as I did in the second paragraph. The latter aspect is prominent when we pursue ontology, epistemology, or metaphysics, and wonder how probable it is that a specific religious belief be true, whether it constitutes knowledge, or what it implies with regard to the ultimate nature of reality. In order to investigate these issues, the content of the relevant belief has to be spelled out with some precision.
Secondly, criteria of reasonableness with regard to beliefs differ depending on the area at issue. For example, given the constitutional freedom of religion in Western countries, it will be legally legitimate to endorse a specific religious belief and to go through the relevant rituals. However, doing so may be unreasonable from an ontological and epistemological perspective, if it is improbable that the belief in question is true and no convincing evidence or arguments for its truth are available. Furthermore, criteria for the epistemic legitimacy of beliefs differ depending on the relevant domain or discipline to which the beliefs belong, such as mathematics, the empirical sciences, law, ethics, or metaphysics. What are these criteria with regard to religious beliefs? In this chapter on the philosophy of religion, I focus on the content of religious creeds, and investigate their legitimacy in the epistemological sense. We will wonder whether there are any reliable primary sources of religious beliefs (section 2). Since there do not seem to be such epistemic sources, and because many alleged divine revelations are falsified empirically, religious explanations have been eliminated gradually from the sciences (section 3). Given the resulting separation between science and religion, pious philosophers have developed various non-science-based strategies for justifying their religious convictions. After providing an overview of these strategies (section 4), I examine an argumentative strategy (section 5). Finally (section 6), we shall invite readers to make up their mind with regard to religious beliefs.
Let us define a religious belief as the conviction that a god, angel, devil, surviving soul, or other supernatural being really exists. According to a demographic investigation of The Global Religious Landscape by the Pew Research Center, published in 2012, 84% of humans on Earth were religiously affiliated in 2010. Given the fact that, on average, religious believers tend to have more children than the religiously unaffiliated and to educate their children religiously, later research on The Changing Global Religious Landscape published in 2017 projects that in 2060 the percentage of religiously affiliated humans on Earth will be 87,5%. If we also assume that most of the religiously affiliated endorse a specific religious belief as defined above, the question as to whether and how a religious creed can be epistemologically legitimate is of worldwide importance.
In general, a belief that p is legitimate in the epistemological sense if there are convincing grounds for concluding that p’s truth is more likely than p’s falsity. Legitimacy in this sense may be a matter of degree, and which degree is considered to be sufficient will depend on the context and the topic under consideration.
In order to investigate whether a belief that p is legitimate, we should trace the sources on which it relies, which may be primary or secondary. An epistemic source is primary if it enables us to discover whether or not it is true that p. For example, our eyes, ears, and other perceptual organs are the primary sources of beliefs about our environment, such as the belief that there is a tree in front of us. Calculating is the primary source of an arithmetic belief, like the claim that 13x24=312. Epistemic sources are secondary if they rely only on results obtained by other sources, for instance, if we hear the testimony of other human beings who claim to have detected that p.
Let us now wonder which kind of epistemic source we learned to rely on when we were taught to adopt a specific religious creed during our infancy. Did we learn to investigate whether any god or other supernatural being exists by exploring primary sources of religious beliefs? Or were we taught to trust our parents and religious teacher, such as a guru, pastor, priestess, imam, or rabbi, so that we had to rely on a secondary source? In order to practice the first approach, our teachers would have had to confront us with a great diversity of religious convictions, such as the core doctrines of Catholic Trinitarianism and Tantra Hinduism, and to instruct us how one can find out whether any of these doctrines is true. Clearly, if interpreted literally, these two religious faiths cannot both be true, since they contradict each other. Whereas monotheist religions contend that there is only one god, who consists of three persons according to the Christian doctrine of the Trinity, a popular version of Tantra Hinduism holds that there are 33 “crore” (= 10million) deities”, that is 330 million gods.
Are there any reliable primary sources or methods of investigation that enable us to discover which of these incompatible religious doctrines is true, or whether there is a true religious belief at all? Philosophers of religion such as the American celebrity Alvin Plantinga have argued that Christian believers do not need any methods of investigation, if at least God has implanted religious beliefs in their minds or hearts. If God did so, these religious beliefs would be warranted, and no further arguments or investigations would be required in order to show their epistemic legitimacy (Plantinga, 2000;2015). However, as soon as Christians discover, for example, that Tantra Hindus endorse religious beliefs that are contradictory to theirs and hold that these beliefs are implanted in their hearts by millions of gods, this discovery is a rebutting defeater of the Christian belief.
Nowadays, all well-educated religious believers will be aware of the plurality of religions on Earth. Consequently, they cannot trust the epistemic legitimacy of their own religious convictions, unless it can be shown by reliable research and primary sources that these beliefs are more likely to be true than each of the competing ones, including universal atheism. Are there any reliable methods of religious research? If so, what are they, and what is revealed if one applies them properly? As the 19th century American philosopher and psychologist William James stressed already in his first lecture on (1902/1977), ordinary religious believers simply follow the conventional observances of their country or community, which are communicated to them by cultural traditions. In other words, they rely on secondary sources. Since the primary sources of religious beliefs allegedly give us access to something supernatural, such as the omnipotent god of Christianity or Islam, one might expect that these primary sources differ drastically from the sources of natural knowledge. Indeed, both according to James and to many recent psychological investigations, the overwhelming “original experiences” of religious originators should be classified as “abnormal psychical visitations” (Murray et al., 2012). Let me discuss briefly what caused Saul’s or Paul’s conversion to Jesus on the road to Damascus as a prominent prototype of a primary epistemic source. Without this conversion, it is unlikely that Christianity would have spread within the Roman Empire.
According to the New Testament book Acts 9:1, when Saul of Tarsus went on his way to Damascus, he was “still breathing threats and murder against the disciples of the Lord”. How should we explain that Saul suddenly converted from a Jewish persecutor of the Jesus-sect to Paul, its main propagator during the first century? Acts 9:3-9 mentions four striking features of Saul’s conversion- experience on the road to Damascus: (1) “suddenly a light from heaven flashed about him”; (2) “he fell to the ground”; (3) “heard a voice” that is attributed to Jesus; after which (4) “for three days he was without sight, and neither ate nor drank”. Three further features are relevant as well. Although in Acts 9:7 it is said that the “men who were travelling with him stood speechless, hearing the voice but seeing no one”, Acts 22:9 quotes Saul himself, saying that (5) “those who were with me saw the light but did not hear the voice”. In Acts 26:13-14, it is added that (6) the light from heaven was “brighter than the sun”, and that (7) all those who journeyed with Saul also fell to the ground.
If we assume that the descriptions of Saul’s conversion experience in Acts are historically reliable to some extent, we should wonder what is the best explanation of features 1, 2, 4, 5, 6, and 7, neglecting 3 for a moment, because according to 5 Saul’s companions did not hear a voice. There is a long history of psychiatric explanations of what happened to Saul, such as that he suffered from an epileptic attack or from paranoid schizophrenia, but these explanations do not account for features 1, 5, 6, and 7. A somewhat superior secular explanation of what happened to Saul has been proposed only recently, and it relies on a careful comparison between the passages in Acts and eyewitness accounts of “the explosive entry of an asteroid fragment over Chelyabinsk in 2013” (Hartmann, 2015, p. 368). What happened to Saul and his companions may have been caused by the nearby impact of an asteroid or meteorite as well.
For example, features 2 and 7 can be explained by the shockwave resulting from an asteroid exploding when it descends within the Earth’s atmosphere, and aspects 1, 4, 5, and 6 are accounted for by the intense ultraviolet radiation caused by such a fireball event. If this is indeed what happened, Saul’s ignorance of the astrophysical knowledge available today explains that he interpreted this perplexing experience in a religious way. Since he perceived the fireball event as the resurrected Jesus appearing to him (3), it is plausible to assume that Saul looked longer into the intense ultraviolet radiation than his companions, whereby he got photokeratitis (feature 4). The content of Saul’s interpretation, to the effect that (3) he heard the voice of Jesus resurrected, and Saul’s radical conversion resulting from his experience, have been explained convincingly by Friedrich Nietzsche in Morgenröte (1881/1964, §68), although Nietzsche knew nothing about asteroids, and endorsed a purely psychiatric diagnosis.
The secular (asteroid) account of what happened to Saul on the road to Damascus overrules the religious explanation, which many Christians still endorse. Quite probably, Saul’s conversion was not based upon any trustworthy primary epistemic source of religious beliefs. Rather, it resulted from Saul’s not knowing the real causes of his overwhelming ordeal.
As the St. Paul-example illustrates, during our long (pre-) history, human ignorance concerning the causes of striking events such as thunderbolts, epidemics, or floods triggered their attribution to divine beings. Many other motives gave and still give rise to supernatural beliefs as well, like longing for a life after death. As David Hume argued in The Natural History of Religion, it is “[n]o wonder [...] that mankind, being placed in such an absolute ignorance of causes and being at the same time so anxious concerning their future fortunes, should immediately acknowledge a dependence on invisible powers, possest of sentiment and intelligence” (Hume, 1779/1976, p. 34). Today, cognitive scientists have proposed supplementary explanations of religious beliefs, such as the hypothesis that our brains contain a Hypersensitive Agent Detection Device. This mental mechanism would have enhanced evolutionary fitness, although it also gave rise to supernatural illusions.
If we define ‘science’ in the broadest sense as the human pursuit of knowledge by means of well-calibrated methods of research, we will understand why from the scientific revolution in 16th-17th century Europe onwards, religious beliefs have been eliminated gradually from science-informed world views. It became ever more obvious that no religious belief could be justified from an epistemological point of view, so that we should wonder why it might be legitimate to endorse such a belief at all. Let me just mention the most important reasons why religious beliefs were eliminated from well-informed world views.
First, numerous religious explanations of empirical phenomena have been overruled by scientific ones because the latter were epistemically superior in many respects, such as testability, falsifiability, and fecundity for further research. Whereas Newton still thought that cosmological features like the fact that all planets move “in Orbs concentrick” around the Sun in the same direction, could be explained only by assuming that God decided to create them like this (Newton, 1730/1979, Query 31, p. 402), both Immanuel Kant and Pierre Simon de Laplace provided purely physical explanations of these features, such as their nebular hypothesis. Similarly, although William Paley still argued in his Natural Theology (1802/2006) that the functional complexity of living beings and their parts (e.g. the eye) could be explained only by the Christian doctrine that God had created the first instances of each species, Darwin refuted this creed of special creation in The Origin of Species (1859/1996) by showing extensively the empirical superiority of his evolutionary hypothesis.
A second reason for eliminating religious beliefs from our scientific view of the world is that many of the factual claims contained in collections of sacred scriptures such as the Bible or the Koran have been shown to be false. For example, whereas according to the Biblical book Genesis I, God created the universe primarily in order to house humanity, present-day cosmological estimates of the actual size of the universe as it has expanded since the Big Bang demonstrate the absurdity of this homo-centric prejudice. Similarly, the many Bible-inspired calculations of the age of the universe, such as Archbishop Ussher’s computation on the basis of biblical genealogies to the effect that God started to create the world in October 4004 BC, have been refuted by numerous results of scientific research. For instance, recently developed radiometric dating techniques have revealed that planet Earth is approximately 4.45 billion years old, and evolutionary biologists estimate that life began on Earth between 4.2 and 3.5 billion years ago. Given the falsity of many factual claims contained in allegedly holy books, it is highly unlikely that they were revealed to humanity by an omniscient deity.
Thirdly, the more scientists and philosophers reflected on the epistemic merits of methods for detecting truths, the sharper they realised that no religious belief is obtained or justified by using any trustworthy method or reliable primary source. This insight is supported as well by the fact that mutually incompatible religious beliefs are endorsed by humans with reference to the same types of alleged primary sources, such as holy books or divine revelations during dreams. From these two results it follows, fourthly, that given the plurality of mutually incompatible religious beliefs, there are no primary epistemic sources or methods available that enable us to discover that any one of these convictions is true, or is more likely to be true than each of its religious rivals. As a consequence, religious hypotheses should be, and have been, eliminated completely from the scientific enterprise.
One might object that scientific progress not only eliminates religious accounts of many empirical facts, since these accounts clearly resulted from ignorance, as Hume argued. Scientific progress also reveals ever more things the causes or origins of which we do not know. It has been suggested that some of these things, such as the postulated Big Bang, should be explained by a religious hypothesis. However, both Christians like Henry Drummond, and many atheists have condemned this proposal as a “god-of-the-gaps” approach. For religious believers the strategy is too risky, because one cannot exclude the possibility of scientific progress eliminating the relevant epistemic gap and its religious interpretation. Atheists will maintain that no religious explanation of any fact will be acceptable anyway, since there are no reliable methods of religious discovery. Many experts have concluded that from an epistemological point of view, science and religion should be separated sharply. For instance, Stephen Jay Gould argued in his 1997 essay “Nonoverlapping Magisteria” that science and religion(s) are concerned with different domains that do not overlap: the domain of facts (sciences) and the domain of values (religions). Will this strategy of a radical separation between religion(s) and science be epistemically beneficial for religious believers? What do you think?
Stephen Jay Gould’s separation strategy confronts religious believers with a difficult dilemma. Either (a) they agree that their religious belief should not be interpreted as a factual claim to truth. Consequently, they should not endorse any more the conviction that a particular god exists in fact. However, this abstention will undermine many of the justifications they adduce in favour of their values. Or (b) they should argue, against Gould, that what has justified the elimination of religious beliefs from the scientific enterprise is not the epistemic unreliability of their primary sources. In order to substantiate this second option, they have to show what these sources are, and how using them justifies the conviction that in fact a specific god exists.
Followers of Søren Kierkegaard will (c) try to escape between the horns of this dilemma by holding that given the many apparent paradoxes of a Christian (or other religious) creed, which transcend our rational capacities, one can (and should) endorse the factual truth of this (or any other particular) religious doctrine by suspending reason completely, and believing it by virtue of the absurd. Only if one does so in all practices of life, can one become one’s true self. In other words, our religious belief should radically overrule reason.
One might model the choice between options a, b, and c as the first node (I) of a decision tree for religious believers. Each of these options may be pursued in different manners, so that they lead to new nodes at level (II). For example, if one endorses (a), and thus embraces a so-called non-cognitivist interpretation of religious beliefs (which arguably do not aim at knowledge), one will re-interpret the conventional utterances of one’s creed, such as ‘God is omnipotent and created the universe’, or ‘Poseidon will save me from drowning’, either as (1) mere expressions of emotions, or (2) as implicit moral claims, (3) as affirmations of belonging to a specific community, or (4) as having these and many other functions that are distinct from making a propositional claim to truth. These are so-called ‘revisionary accounts’ of religious language, since most religious believers intend to make factual statements when they assert that their god(s) exist(s) and did or will do something.
According to ‘non-revisionary accounts’ of religious language, existence claims with regard to specific gods such as Yahweh, God, Allah, Zeus, or Zhenwu typically aim at stating a matter of fact. Both options (b) and (c) endorse the so- called face value theory of religious language. They take religious utterances at face value, and interpret them as closely as possible to what they seem to mean at first sight. Since option (c) denies the relevance of religious epistemology, I shall focus here on option (b), which is a node for the following dilemma at level II. If (b) a religious statement is a factual claim to truth, either (5) endorsing it can be epistemically legitimate only if based upon relevant types of evidence, or (6) no evidence is needed for its epistemic legitimacy. As Alvin Plantinga (2000;2015) argued, (6) is correct for Christians if God exists, since, if so, probably He implanted properly Christian beliefs into the minds of Christian believers. Hence, these beliefs will be warranted even if no evidence whatsoever supports them.
If we think that evidence is needed in order to endorse legitimately the factual claim to truth that God exists (5), we arrive at the node for the next dilemma, at level III, which is concerned with the types of evidence that are relevant for legitimising religious beliefs like this. According to the first horn of this dilemma, option (7), the evidence for a specific religious belief will become available only to those who engage receptively within the relevant religious community for quite some time (e.g. Cottingham, 2014). As a consequence, Cottingham concludes, one cannot reach “a final verdict on the relevant truth-claims from outside the forms of practical and affective engagement through which alone genuine understanding flourishes” (Cottingham, 2014, p. 171).
Both options (6) and (7) run into trouble if confronted by the problem of the plurality of religions. For instance, the Christian belief that there is only one god, called God, who is omnipotent and omniscient, is contradicted by polytheistic religious beliefs, such as the Tantra-Hindu conviction that there are 330 million gods, so that not each of these beliefs can be true. If representatives of both religions choose option (6), according to which no evidence is needed for endorsing legitimately a religious belief, they will have to conclude that the truth of the belief they endorse is very unlikely, given the large quantity of mutually incompatible religious beliefs. The same holds for option (7), because adherents of many different and mutually incompatible religious convictions will say that they have discerned the truth of their belief only after a long-lasting involvement within the relevant community.
On these and other grounds, many religious apologists will prefer the second horn of the dilemma at level III, according to which (8) the evidence for a specific religious belief (and against the competing religious beliefs) is accessible to non-believers as well, at least to some extent. In other words, some primary sources of religious beliefs must be publicly available, and it should be possible to justify a specific religious belief by using these sources and reliable methods of research.
However, given the elimination of religious beliefs from the scientific enterprise, illustrated in section 2 above, option (8) is quite challenging. Have religious beliefs not been excluded from the sciences because no reliable methods of research or trustworthy primary epistemic sources could support any of them? Will not each piece of empirical evidence adduced to the credit of a specific religious belief run the risk of merely advocating a god-of-the-gaps, that is, postulating a religious explanation for things that the sciences have not yet explained, but might explain in the future? Since option (8) is challenging, it may be interesting to devote the next section to one of its most prominent proponents.
One of the most sophisticated attempts to elaborate option (8) is to be found in Richard Swinburne’s book The Existence of God (1979/2004). Using Bayesian probability theory, Swinburne intends to show that given the total empirical evidence pro and contra, “theism is more probable than not” (Swinburne, 1979/2004, p. 342). He defines ‘theism’ as the thesis that God exists, while the word ‘God’ is introduced as the name of a person picked out by the following description: “a person without a body (i.e. a spirit) who necessarily is eternal, perfectly free, omnipotent, omniscient, perfectly good, and the creator of all things” (Swinburne, 1979/2004, p. 7).
How does Swinburne avoid the god-of-the-gaps risk of option (8) that the empirical evidence adduced in favour of theism will be explained later by superior scientific theories, so that theism will be superseded? Whereas he claims on the one hand that theism purports to explain “all our empirical data”, he argues on the other hand that the empirical evidence for theism is either “too odd” or “too big” for science to explain (Swinburne, 2004, pp. 66, 93, 74-5). Furthermore, although he states that theism is a “large-scale theory of the universe”, which closely resembles “large-scale scientific theories” (Swinburne, 1979/2004, p. 3), he also holds that there is no risk of an empirical refutation of theism in the future, since theism “does not yield predictions such that we can know only tomorrow, and not today, whether they succeed” (Swinburne, 1979/2004, p. 70).
In order to use Bayes’ theorem for calculating the probability that theism is true given all available evidence, many conditions have to be met. Let me mention three of them only. First, theism should be defined meaningfully, and it is debatable whether Swinburne’s traditional definition of ‘God’ succeeds in this respect. Since we give meaning to the word ‘person’ by applying it to human beings who are corporeal, it may be argued that one annuls the meaning of ‘person’ by stating that God is a person without a body. Secondly, Bayes’ theorem can be applied to theism only if specific empirical facts are more (or less) likely if God exists than if God does not exist. In other words, the hypothesis of theism should have some predictive power if it makes sense at all, and in order to grasp this predictive power we humans should be able to know God’s intentions, at least to some extent. Thirdly, in order to show that God’s existence is more probable than not, one should attribute a prior (initial) probability to theism which is not too low. Since there are infinitely many different monotheistic and polytheistic doctrines, which contradict each other in many respects, one might argue that the prior probability that one of them is true approaches zero, because there are no convincing grounds for attributing different prior probabilities to these proposals. If so, the prospects of producing convincing inductive arguments for this specific version of theism are negligible.
There is no space here for explaining how Swinburne or other religious apologists have attempted to resolve these problems (cf. Philipse, 2012/2014, chapters 7-11). Let me just mention some main types of empirical arguments put forward in support of the theistic doctrine as defined. According to (A) cosmological arguments, the existence of the universe confirms the hypothesis of theism, since allegedly it is more likely that our universe exists if theism is true than if theism is false. In arguments (B) from temporal order it is claimed that probably a Godless universe would be quite chaotic, so that the fact that our universe is governed by laws of nature corroborates theism as well. So-called fine-tuning arguments (C) start from the premise that life in general and the human species in particular can evolve only in a universe the natural laws and initial conditions of which are quite specific, compared to the large set of conceivable laws and initial conditions. Then it is argued that these facts of fine-tuning are much more probable if God exists than if God does not exist, since, so it is assumed, God intended to create a world in which humans could evolve.
In order to demonstrate by means of Bayes’ theorem that theism is more probable than not, one should not only attribute a plausible prior probability to this hypothesis, but also argue that the total evidence in favour of theism overrules sufficiently the evidence against. According to theists such as Swinburne (1979/2004), many other facts apart from (A-C) confirm theism empirically, such as (D) the overall beauty of nature, (E) the fact that conscious beings exist, (F) the complex brain-mind connections in humans, (G) our moral awareness, (H) the need for humans to make significant moral choices, and (I) the presence of religious experiences. Furthermore, theists will argue that facts (A-I) overrule other facts that seem to disconfirm theism, such as the existence of (J) moral evil and the many kinds of (K) natural evils.
Critics may reply that theism is not at all confirmed by facts (A-I), whereas there are many more empirical arguments against theism than its proponents take into account. As scientific progress in cosmology reveals, for example, life is extremely rare in our universe (L). God would never have created such a cosmos, if He were perfectly good in Swinburne’s sense. Furthermore (M), since monotheism arose only rather late in human (pre-) history, if God existed he would have been hiding himself from humans during many millennia, and does not reveal Himself to each human individual today. Because allegedly God is a good father for all human beings, he would not conceal himself for anyone of us, so that facts of divine hiddenness show that God does not exist (Schellenberg, 2006;2015). Furthermore, as neuro-scientific research has shown ever more convincingly (N), mental phenomena can exist only on the basis of specific neural substrata, so that it is highly unlikely that God as defined by theism exists at all.
Questions as to whether a specific divinity exists are not only interesting from an epistemological point of view. It can be of great practical importance whether one endorses or refuses to sustain a particular religious belief.
As Daniel Dennett (2006, p. 15) stresses, “for many people, probably a majority of the people on Earth, nothing matters more than religion”. Hence he “can think of no more important topic to investigate” (p. 7). Whereas Dennett focuses on the evolutionary, social, economic, and psychological functions of religious convictions, the core question of the present chapter is an epistemological one: can it still be reasonable for intelligent and educated people in our times to endorse a religious belief that a particular god exists? Since there is no consensus between experts on this issue, each of you will have to make up your mind yourself. This chapter aimed at providing an overview of possible options in this respect, and motivating readers to make up their mind with intellectual integrity.
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