Verification Vs. Falsification: The Birth of the Philosophy of Science

The early 20th century was characterized by a new spark of interest in the philosophy of science. Thinkers strived to define what scientific knowledge really is and came up with various views about the criteria that a certain knowledge must possess to be considered scientific. As a result, many theories emerged. One of them was the positivist verification principle. On the other hand, opposing the positivist view was the principle of falsification proposed by Karl Popper. What are these principles? What do they have in common, and how do they differ?

First and foremost, let’s take a look at the historical context of the period in which the principles of verification and falsification emerged. What is these theories’ place in the history of philosophy?

At the end of the 19th and the beginning of the 20th century, philosophy was dominated by Hegel’s absolute idealism. Hegel had great influence in the field of philosophy and gained lots of students and followers throughout his academic career and beyond. He was so influential that he completely took over the philosophical scene and obscured any other philosophical approach.

This represented a break in British philosophy, which has always been empirically oriented. Absolute idealism is a strictly metaphysically oriented philosophy that views the world as underlying a principle that is beyond the world of perception. Its followers thought of themselves as talking about the fundamental truths of the world, and these truths were not available to scientists. This is because scientists have to treat the world as consisting of distinct particular objects and can only describe and explain the relationship between these objects. On the other hand, idealists strive to understand reality as a whole, as something that’s based on an underlying principle that is transcendent and cannot be perceived by the methods that scientists use.

British empiricism is founded upon totally different grounds. Empiricists consider everyday beliefs and experiences as the right way to examine the world and thus recognize the truth. They think of science as the model according to which we must navigate the world and examine it in its totality.

Contemporary analytic philosophy has a strong resemblance to empiricism. It carries on the ideal of overcoming great philosophical systems and traditional philosophical methods. The main goal that the early representatives of analytical philosophy set for themselves is, in fact, taking a critical attitude towards the overall philosophical tradition with a special emphasis on the rejection of metaphysics. This critical attitude resulted in some very influential questions arising. A key question was one concerning the validity of metaphysical theories and of philosophical knowledge in general. In other words, the questions were: what is the criterion of truth of philosophical knowledge? What should the means and the methods of philosophy be?

These questions arose as a result of the dominance of speculative metaphysics, shifting the focus of attention to the very methodology of philosophy as a science and as an activity. This is how the philosophy of science began as a separate discipline of its own: it was, from the very beginning, connected to the investigation of the validity of philosophical knowledge.

The two principles of verification and falsification emerged as a way of figuring out a method that would determine the validity and truthfulness of philosophy, or really, of any pursuit of knowledge. The first one that emerged was the verification principle.

So, what is the verification principle, and what does it say about science? The English philosopher Alfred J Ayer presents it most clearly in his book Language, Truth, and Logic. The verification principle is a principle that allows us to determine whether a certain philosophical statement (sentence) has a meaning or whether it’s completely meaningless.

The proponents of the verification principled rebelled against the presumed meaninglessness of much of philosophy. The idea was that we could (and should) eliminate meaningless sentences from the field of philosophy.

The way one could go about doing that is by carefully analyzing every word and term in a given sentence and checking whether the word corresponds to the already assigned literal meaning of it. If the meaning of every word in the sentence is clear, not confusing, and non-ambivalent, one should proceed to the second point of the principle: asking which observations, and under which circumstances, would determine the statement positively or negatively. If we can come up with such observations that would help in giving a clear answer, then we should conclude that the given sentence is meaningful.

This means that a given sentence has a meaning if we know how to verify the statement that it is trying to express. This is where the principle gets its name.

Let’s borrow an example given by Moritz Schlick, the founder of logical positivism. The sentence to be analyzed is “There are mountains on the dark side of the moon.” It’s clear that this sentence does not contain any ambiguity and confusion and that its meaning correlates to the literal meaning of every word and of the sentence as a whole.

The second part of the principle should be applied now. Is it clear which observations would verify the existence of mountains on the dark side of the moon? When Schlick was coming up with this example, there was no way to actually go to the moon and check, as the technology was not there yet. However, there was still an idea about the kind of observations that would determine that for us: it was possible to imagine which observations would confirm the sentence, even though such observations were practically impossible at the time. Because of this, the sentence is in principle verifiable and thus meaningful.

Now let’s take a different example from the metaphysical corpus: the (very Hegelian) sentence that “The Absolute permeates evolution and development, but he himself is incapable of it.” This sentence causes confusion at its very first read. What does the term “Absolute” even mean? The terms “evolution” and “development” clearly do not have the same literal meaning that they usually do as well. Also, the sentence as a whole is confusing, and it is not clear what it is trying to say. Secondly, we are unable to even imagine what kind of observations would enable us to determine whether the Absolute permeates evolution and development—there is simply no way of checking whether that’s true. Because of that, under the verification principle, the sentence is meaningless and does not have any sort of value for philosophy or science.

Karl Popper, a very important and famous philosopher of the 20th century, was one of the first to criticize the verification principle. Crucially, he proposed his own alternative: the falsification principle. Although seemingly opposite, Karl Popper’s theory of falsification is in many ways analogous to the ideas behind the verification principle.

Popper’s theory of falsification assesses the meaning of statements in terms of their falsifiability, whereas the verification principle determined the meaning of a sentence in terms of its verifiability. Popper presents this theory as a reaction to the theory of verification. In his work Logik der Forschung (The Logic of Scientific Discovery), he insists that the verificationist criterion of meaning should be abandoned and replaced by a different criterion: one which differentiates between empirical (scientific) and trans-empirical (non-scientific, metaphysical) questions and answers. This criterion, according to Popper, should be the amenability to refutation.

But what does this criterion really consist of? Well, Popper suggests that instead of looking for arguments in support of scientific positions, they should be subjected to constant attempts at refutation. The theory which withstands the most (or even all) attempts at refutation should be accepted.

A key feature of scientific theories, according to Popper, is that there could be evidence that would disprove it, in principle. Theories should be subjected to the most severe criticism and experimental testing. This is the case because, according to Popper, true scientific theories are never fully confirmed since discontinuous or disprovable observations (observations that are inconsistent with the empirical predictions of the theory) are always possible, regardless of the number of confirmed observations that have been shown to be consistent with the theory.

According to Popper, some scientific disciplines that have claimed scientific validity, such as astrology, metaphysics, Marxism, and psychoanalysis, are not empirical sciences because their subject matter cannot be falsified, that is, refuted in the same way that they can other knowledge of science be refuted.

As we have both principles of verification and falsification presented, at this stage, it’s necessary to point out each of their weak points and limitations. That’s why we’ll mention some of them below in this part of the text.

Let’s start with the verification principle. The principle of verification faced several difficulties from the very beginning—such as, for example, the problem of verification of statements expressing natural laws, which are inductive generalizations of present and past experiences, and, therefore, cannot be fully verified. The same goes for statements from the field of history and geology, which refer to events in the past that are also not verifiable in experience, as well as statements that express one’s own and others’ psychic experiences. Also, it is often criticized that the very initial formulation of the principle, which reads: “The meaning of a sentence consists in its verification,” cannot be subjected to the verification that the positivists themselves assumed as the criterion of meaning. Accordingly, the very formulation of the principle turns out to be meaningless.

Popper’s falsification principle has its weak points as well. First and foremost, according to Popper, when a theory is falsified, scientists must reject the theory and move on to a new one. However, in practice, scientists often modify or refine a theory to reconcile it with contradictory evidence. This involves the introduction of many other hypotheses, which may not be directly testable and may complicate the falsification process.

Also, Popper’s principle assumes that there is a clear distinction between what counts as evidence for or against a theory. However, in practice, there may be multiple ways of interpreting evidence, and different theories may make the same predictions. This means that there may be cases where evidence does not clearly falsify a theory or where multiple theories are compatible with the same evidence.

At the very end of the text, it’s important to mention that the limitations that we’ve shown above do not necessarily invalidate the principles, but instead, they highlight the complexities and challenges of applying them in practice.