Evidence. Evidence. Where is the evidence? Show me the evidence or I won’t believe. Such is a typical response of the modern atheist when asked why they don’t believe in God.
By “evidence” they mean empirical evidence; the kind of evidence used by science. Now, empiricism as a starting point to validate truth claims has a long and distinguished history. So how far can empirical evidence get us? Let’s find out what it can’t get us.
The following is a short, non exhaustive list of stuff almost everyone believes in but for which there is no empirical evidence:
Objective reality. When you sit on a chair, you don’t know empirically that the chair exists; all you know is that your mind is giving you the experience of sitting on a chair. To know that the chair has mind-independent reality, you need to go outside your mind to check. Good luck with that.
Causation. Have you ever seen a cause? No. You see things happen after other things, then your mind infers that causation is there. So causation could be illusory, or you might not understand it. Perhaps no one does.
Other minds. You know that you have an inner consciousness. You don’t know that anyone else does. Have you ever seen anyone else’s consciousness? Is it valid to extrapolate from yourself to everyone else in this way? After all, you are a small sample size.
Morality. To say that anything is right or wrong presupposes that there is an objective standard that whoever you are criticising should adhere to. Where is this standard? Can you prove empirically what standard we should use?
Human logic. If the mind evolved, how do you know that this has progressed long enough to produce anything useful? It might take another million years for all you know. Future humanity might consider our science and mathematics a laughing stock.
Abstractions. Abstractions such as “truth”, “knowledge”, “circle”, “hypothesis” and so on do not exist empirically, so how do you know it makes sense to use them? You don’t.
Mathematics. Prove empirically that 2-5=-3. Should be easy. Start with 2 apples, take away 5, for a total of -3 apples. Now pick up one of your -3 apples and eat it. You have successfully proven mathematics empirically. Congratulations.
The past. Your memory is reliable, or is it? Can you go back to check?
History. Was Julius Caesar assassinated? Can you prove it empirically, rather than from dusty old books?
Love. “I love you!” Really? Show me the evidence.
Any empirical fact you can think of will necessarily be based on assumptions such as the above that can’t themselves be proven empirically. For example, to say “I just saw a cat outside my window” assumes a world outside your mind, that you weren’t hallucinating or dreaming, an ability to recognise cats, an ability to construct sentences correctly, the reliability of your memory etc.
Any scientific idea will add on more assumptions, as it must assume that the world is comprehensible both in itself and to us, that scientific concepts such as “hypothesis” and “falsification” make sense, that causation is real and so on. The deeper the level of abstraction, the more ideas must be assumed.
Let’s look at causation for a moment. Science assumes that causation is real but doesn’t tell us how. If for example matter is made of ideas in the mind of God (I am not making this up), then what we think of as physical causation is actually connections between ideas in God’s mind, and all science is theology – and the evidence can’t tell us otherwise. Another example: what if our minds told us that causation works backwards? If they did, no doubt our science would include not evolution, but devolution; not natural selection, but natural unselection – and again, the evidence wouldn’t tell us otherwise.
It follows that there is no such thing as a purely empirical fact. To put it another way, any empirical fact is a non-empirical sundae with an empirical cherry on top. If the non-empirical sundae is wrong, the empirical cherry won’t make it right. Likewise, if the non-empirical sundae is correct, it will still be correct without the empirical cherry.
Looking at examples of empirical evidence only reinforces this point. When I think of empirical evidence, I think of (say) finding fossils in the ground. But it gets a lot more esoteric than that. Consider the following from this paper about the Higgs boson:
Correspondingly, the signal strength relative to the expectation for the standard model Higgs boson is found to be 0.78 ± 0.27 at the Higgs boson mass of 125 GeV. Earlier, the CDF and D0 experiments at the Tevatron reported, for mH = 125 GeV, an observed (expected) 95% CL upper limit of 7.0 (5.7) times the standard model expectation.
Such statistical methods stretch the definition of “empirical” to breaking point.
This means there can be no hard boundary between science and other types of knowledge. Therefore if the success of science gives you confidence in science (and why not), it should also give you confidence in the non-empirical aspects of human thought.
Fine. Now what?
Where to proceed from here?
No one is an acausationist who won’t believe in causation until someone shows them evidence for it, nor does anyone argue for it; it’s just assumed. If the human instincts that evolution has given us about causation, time and space, other minds, objective reality, abstract thought etc should be accepted without argument or evidence, and evolution has given us an instinct to believe in God, you are also fully justified in believing in God without argument or evidence.
What you cannot do is reject anything solely because you believe it has no empirical evidence. If you do, you must also reject the entire above list – objective reality, causation, other minds, the validity of human logic, morality, abstract thought, history, mathematics.
Clearly that cannot be done. A consistent empiricism is therefore a complete non-starter. The challenge, then, is to find a more balanced approach that takes into account human instinct and logic rather than just empirical evidence.
I don’t have all the answers, but my own take is this: all the basic human instincts about reality are approximately true. Why all?
Since all human knowledge is ultimately based on unprovable instincts, it makes no sense to use half those instincts to attack the other half as unprovable. Secondly, whatever instincts we have ultimately came from the same source, so there is no basis for privileging one over another. There are only two consistent positions available to us: we assume they are all true and proceed on that basis, or they are all false and all human knowledge is fiction.
So if we are to avoid a scepticism of everything, the role of logic and evidence is to show us exactly how our instincts are true rather than trying to overturn them.