Do we know something only after we have verified it empirically, after we have checked it directly by looking at the facts? Surely not. We know many things that we have not checked ourselves and could not check by ourselves. For me, that knowledge includes propositions about ancient history, about nuclear particles, about heaven and hell, and so forth. In many areas, we accept testimony from those we trust, even though we are unable to verify things for ourselves. As Mavordes, argues, the demand for verification is a demand that is sometimes, but not always, appropriate. It is appropriate when we are in doubt, but to make it a general requirement for knowledge would mean that every verification would have to be verified ad infinitum.
Therefore verification is not essential to knowledge; we may know something without having it verified empirically. But perhaps at least the possibility of verification is essential. Some have charged that Christianity cannot possibly be verified and therefore is not worthy of serious consideration. That charge, however, is (i) often based on the presuppositions of logical positivist philosophy and thus is open to criticism on theological lines. And the type of verification that logical positivists demand uses the methods of autonomous science, which the Christian cannot accept. (ii) Mavrodes offers a simpler reply: verifiability cannot be a general criterion for knowledge, because often we cannot tell whether a statement is verifiable unless we first ascertain that it is true. (iii) Unlike verification, verifiability cannot serve as a basis for knowledge; at most it can be a necessary condition of it. Even if all knowledge must be verifiable, not all verifiable propositions constitute knowledge. “The moon is made of green cheese” is verifiable but false and therefore not an item of knowledge.
Many philosophers have pointed out that our senses deceive us, that it is not as easy as it seems to “check out the facts” by sense-experience.
D. The Scientific Method
The “popular understanding of the scientific method” that we mentioned earlier is really a serious oversimplification. Scientists do not just “check out the facts” by means of sense-experience. (i) Generally they use instruments, rather than their naked senses, because the senses by themselves are generally not sufficiently accurate for scientific purposes. But the instruments that scientists use interpose a great deal of human theoretical ingenuity between the observer and the things he observes. When he uses such instruments, the scientist is not only checking his theory with observations, he is also checking out his observations by means of theory-dependent instruments. (ii) Scientific work does not consist in just making and reporting observations but in analyzing and evaluating data. (iii) Scientific theories do not just merely report observational data; they go beyond it. Scientific laws are usually general; they claim to hold for the entire universe. (iv) What we “see,” “hear,” “smell” “taste,” and “feel” is influenced by our expectations. Those expectations do not just come from sense-experience but from theories, cultural experience, group loyalties, prejudice, religious commitments, and so forth. Thus there is no “purely empirical” inquiry. We never encounter “brute,” that is, uninterpreted, facts. We only encounter facts that have been interpreted in terms of our existing commitments. (v) Often, then, scientists do not recognize data that contradict their theories. But even when they do, they do not immediately accept such data as refutations of the theories in question. An apparently contradictory datum constitutes a “problem” to be solved in terms of the theory, not a refutation of it. Only when the problems multiply and alternative theories begin to look more promising will the scientist abandon his theory for another. For all of those reasons, the work of science is far more than merely “checking out the facts.” And if scientists are unable to separate theory from fact, nonscientists can hardly be expected to do so. Science does not operate by means of a pure empiricism, and certainly the rest of us cannot be expected to either.
E. Empiricism Too Limited
If we consistently followed an empirical approach to knowledge, we would have to abandon many claims to knowledge that otherwise we would make without hesitation. (i) Empiricism cannot justify a general proposition, such as “all men are mortal” or “F=MA.” Such general propositions always go beyond anything we can observe, because they encompass the whole universe. Similarly, the propositions of logic and mathematics, propositions that claim to be universally true, cannot be established on an empirical basis. (ii) Empiricism cannot justify any statements about the future, for no one has known the future by sense-experience, and so empiricism cannot justify scientific prediction. Thus we must either drastically limit the scope of what we call “knowledge” or else abandon empiricism. (iii) As Hume pointed out, empiricism cannot justify any statements about ethical values. Statements about sensible facts do not imply anything about ethical goodness or badness, right or wrong, or obligation or prohibition. But as we have seen above in C, epistemology is a subdivision of ethics, and knowledge depends on our adoption and use of ethical values. If empiricism cannot justify the language about empirical values, then it cannot justify any claim to knowledge. (iv) Therefore empiricism cannot justify empiricism. For empiricism is a view of how one ought (an ethical “ought” ) to justify his beliefs, and on an empiricist basis, we cannot justify from sense-experience the proposition that we ought to justify our beliefs in that way.
F. Knowledge of God
Empiricism also rules out claims to know God, if God is thought to be invisible or otherwise resistant to empirical “checking procedures.” For some empiricists, that fact rules out the knowledge of God. For Christians, it rules out empiricism as a general theory of knowledge.
What are the “facts” that empiricists believe we directly perceive? These
“facts” are difficult to identify, as we have seen. Are there any “facts” about which we can be certain? Some people have suggested that if we cannot know the world infallibly through our senses, at least we can know infallibly our own sense-experience! For example, I have a sensation of greenness. That may or may not mean that there is something green in my vicinity; my senses may be deceiving me. One thing that I do know, however, is that I have a green sensation. (Sometimes this is called a green “sense-datum.”) Well, maybe so. But notice that here the empiricist has shifted his ground pretty drastically. Instead of a claim to know the world by means of sense-experience, he now claims to know only his sense-experience, only his ideas. Instead of knowing “facts,” now we know only a certain type of fact- those about our own subjectivity. And on the basis of those facts, we can determine nothing about the world beyond our own minds. Just as we saw that in the final analysis there is no difference between rationalism and subjectivism, now we see that there is no difference between empiricism and subjectivism.
H. A Christian Analysis
Like the problems of rationalism, the problems of empiricism are essentially spiritual. Like rationalists, empiricists have tried to find certainty apart from God’s revelation, and that false certainty has shown itself to be bankrupt. Even if the laws of logic are known to us (and it is unclear how they could be on an empirical basis), we could deduce nothing from statements about sensation except, at most, other statements about sensation. Thus, once again, rationalism becomes irrationalism: a bold plan for autonomously building the edifice of knowledge ends up in total ignorance.”
(Frame, DKG, 115-119)