Religion and epistemology

2. Evidentialism characterized

Why has discussion centred on these arguments, and why does it matter which group is stronger? Indeed, suppose there are no good arguments for religious or theistic belief at all: why should that be thought to create a problem for the believer? To see why we must understand evidentialism with respect to religious belief (‘evidentialism’ for short). Evidentialism has been the dominant (though not the sole) way of thinking about these matters from the Enlightenment to the present (again, in the Western world). The evidentialist thinks a person who accepts a religious belief must have evidence for that belief. In particular, they must have propositional evidence for it – evidence from other things they believe. And this is why arguments are crucially important: an argument is simply a way of organizing and presenting your propositional evidence for some belief or other. Just to simplify matters, let us follow current custom and think for the most part about theistic belief, belief in God; later we can think also about beliefs that go beyond theism, such as beliefs that distinguish Christianity from Islam and Judaism.

The evidentialist, therefore, thinks a believer in God must have evidence for that belief – but must for what? What will be the matter with them if they do not? The answer, according to the evidentialist, is twofold. In the first place, if they have no (or insufficient) evidence, then the belief will not constitute knowledge. The believer will know that there is such a person as God (that belief will have warrant for them) only if they have propositional evidence for it – only if they have a good argument for it. But the stakes here are considerably higher than that. For if the believer does not have evidence, then, according to the evidentialist, not only will they lack knowledge, they will also be unjustified in holding this belief; they will not be rationally justified.

But what is this justification, and why do we need it? Why is lacking it a problem? And why should the justification of theistic belief be so closely linked to the discussion of theistic and anti-theistic arguments? To answer these questions, we must go back to the beginnings of modern and Enlightenment thought on these questions, to the genesis of Locke’s Essay Concerning Human Understanding (1689), one of the most influential sources of thought on these topics (see Locke, J. §7).

Locke lived through one of the most turbulent periods of British intellectual and spiritual history; it was in particular the religious ferment and diversity, the enormous variety of divergent religious opinion, that caught his attention. There was the Catholic–Protestant debate, and within Protestantism there were countless disagreements and controversies and many warring factions. Locke was deeply concerned about this blooming, buzzing confusion of religious opinion and the civil unrest that went with it. His Essay is at least in part designed to ameliorate this problem.

The source of this confusing welter of inconsistent religious opinion, Locke thought, was the propensity of people to indulge themselves in unjustified belief. But what is it to be justified (or unjustified) in holding a belief? According to Locke (as well as René Descartes (§7), the other of the twin towers of modern Western epistemology), there are epistemic or intellectual duties, or obligations, or requirements:

We have a duty to regulate our belief a certain way. If we do not, we are accountable. One who regulates belief in this way has the satisfaction of ‘doing his duty as a rational creature’; such a person ‘governs his assent right and places it as he should’. Rational creatures, creatures capable of holding and withholding belief, have duties and obligations with respect to the regulation of their belief or assent. And the central core of the notion of justification (as the etymology of the term indicates) is this: a person is justified in an action or belief if, in taking that action or holding that belief, they violate no duties or obligations, conform to the relevant requirements, are within their rights. To be justified in believing something is to be responsible in forming and holding those beliefs; it is to be flouting no duty in holding them. This way of thinking of justified belief (together with analogical extensions of one kind or another) has remained dominant from Locke’s day to this.

Now Locke believed that if only everyone could be persuaded to restrict assent to those beliefs in which they were justified, we would no longer be confronted with this confusing welter of religious belief. His reasoning is as follows. A belief is justified for me, he says, just if I am within my epistemic rights, am flouting no duties or obligations in holding that belief. But what are my duties or obligations in this area? According to Locke, the central epistemic duty is this: to believe a proposition only to the degree that it is probable with respect to what is certain for you. Which beliefs are certain for you? There are two kinds. First, according to Locke (here again he concurs with Descartes), there are propositions about your own immediate experience that are certain for you: that you have a mild headache, for instance, or that you are thinking about dinosaurs. And second, there are propositions that are self-evident for you: necessarily true propositions so obvious that you cannot so much as entertain them without seeing that they must be true. (Examples would be simple arithmetical and logical propositions, together with such propositions as that red is a colour, and that whatever exists has properties.) Propositions of these two sorts are certain for you, and you are automatically justified in believing them; as for other propositions, you are justified in believing any one of them, says Locke, only to the degree to which that proposition is probable with respect to what is certain for you. (Here he differs from Descartes, who seems to say that you are justified in believing a proposition that is not certain for you only if that proposition follows deductively from propositions that are certain for you.) According to the whole modern foundationalist tradition initiated by Locke and Descartes, therefore, you have a duty not to accept a proposition unless either it is certain for you, or it is (at least) probable with respect to what is certain for you. If a proposition is not certain for you, you have a duty to refrain from believing it unless you have propositional evidence for it. But it was Locke’s belief that if we all did our epistemic duty and believed only propositions we could see to be probable with respect to what is certain for us, we would not find ourselves in disagreement, or at least would not disagree nearly as often.

Returning to theistic belief, we can see how the above thought about justification applies. First, this belief is not certain for us: it is neither self-evident (since there are atheists and agnostics, it is not such that grasping or understanding it guarantees accepting it); nor is it about one’s own mental states. Therefore theistic belief, on Locke’s way of thinking, is justified only if there is propositional evidence for it – more exactly, a person is justified in accepting theistic belief only if they believe it on the basis of a good argument for it, an argument whose premises are certain for them. And this is the linchpin of the way of thinking about the justification of theistic belief that has prevailed from Locke’s time to ours. Theistic belief is justified only if it is probable with respect to what is certain; it is probable with respect to what is certain only if there are good arguments for it; therefore theistic belief is justified only if there are good arguments for it. But then of course it is very easy to see why discussion of theistic belief has tended to focus on the arguments for and against theism.

Now Locke does not argue for this position; he simply announces it. Subsequent thinkers who have discussed the justification of theistic belief have for the most part followed him here, both in announcing the position and in failing to argue for it. Thus W.K. Clifford trumpets that ‘it is wrong, always, everywhere, and for anyone to believe anything upon insufficient evidence’ (1879: 183); his is perhaps the most prominent in a considerable chorus of voices insisting that there is an intellectual duty not to believe in God unless you have a good argument for that belief. (A few others in the choir are Brand Blanshard (1974: 400–), H.H. Price, Bertrand Russell and Michael Scriven.) According to all these thinkers, if you accept theistic belief without having a good argument for it, you are going contrary to epistemic duty, are therefore unjustified in accepting it, and are living in epistemic sin.