Science and the Problems of Falsifiability

Regarding my previous post about falsifiability, here are some logical and philosophical problems with falsifiability as a criterion of knowledge (science).

1) Historical problems: The first problem with falsifiability is with what scientists actually do: Falsifiability does not explain what scientists have done, or do, when they are presented with tests that falsify their theories. Scientists have shown a strong tendency to keep their theories intact (in short term that is). They do not tend to, rightfully, throw away a theory because of one test.

This happens to be true about Newton and Einstein, that decided to keep their theories even when a test showed the theory appeared to be false. And obviously, it was the test that was false, not the theory. We can clearly see that this was the right thing: Imagine if Newton had thrown away his theory just because some tests about the moon had shown unpredicted results.

The answer of an advocate of falsifiability to this historical problem is fairly simple, and I think acceptable to some extent. Firstly, the test must be repeatable, which means it’s not just one test, but one test that repeatingly keeps showing abnormal results. It’s still the same test, but here we could be fairly sure that we are not doing anything rush. Also, another answer is falsifiability is not a historical method, but an imperative methodology: It’s saying what scientists should be doing, not what they have done.

2) The practical problem of Duhem – Quine thesis: The thesis itself is simple, we cannot test any theories without testing assumptions and other theories that have made them in the first place. Take for example theory T which is made of other assumptions and theories t1, t2 and t3. When we test T, we are also testing t1, t2 and t3. This is not so much of a problem for other methodologies as it is for falsification. The question is, what has been falsified? T itself, or any of t1, t2 or t3?

Let’s logically formulate this:

T=(t1 ∧ t2 ∧ t3)

We should remember that in order to falsify T, we either need to have falsified T itself, or any other one of t1, t2 or t3. The problem here is more likely practical: How do we know which is actually falsified? Assuming that we can know all of t1, t2 and t3.

The advocate of falsifiability here will have an answer, which seems logically plausible, but in practice turns out very hard or even impossible (if we take Quine seriously): As long as the theory is not falsified, we continue testing it. When it does falsify, well there is no other way and we have to test our other sub theory-assumptions as well.

So, falsifiability as a methodology is not likely to be practical. But then rises a logical problem from Duhem-Quine thesis, which is very problematic for falsifiability as a criterion of knowledge.

3) The logical problem of Duhem-Quine thesis: The formulated theory T above still works here, let’s look at it again:

T=(t1 ∧ t2 ∧ t3)

What will happen if t1 is non-falsifiable? As we can see above, T is still falsifiable. It will be falsified if T or t2 or t3 are falsified. So, what happens to the idea of falsifiability being a criterion of knowledge (science)?  If “any” of the pre-assumptions that we had in order to reach to T turn out to be non-falsifiable, it will show that science is not all falsifiable.

The most fundamentals of science turn out to be non-falsifiable: “The world is real” or maybe better “We can know objective things about the world”. If we can know that we cannot know, then we can know, therefore this statement is not falsifiable. It always has to be true, since if it is not true, it is true.


In the end, falsifiability by itself will not be enough. It has been suggested that we add things to it, or abandon it and take a whole other rout. In any case, although it may be a good way to show what is “not” scientific, it is not a good way of showing what is. And although it can work about some areas of knowledge which are somehow obviously not scientific, about those grey areas is not as useful.


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8 thoughts on “Science and the Problems of Falsifiability”

  1. The most fundamentals of science turn out to be non-falsifiable: “The world is real” or maybe better “We can know objective things about the world”.

    This is an old problem, and presents no practical difficulty for science. Either the world is real, and comports more or less with our understanding of it (seeing as how our understanding of the it has allowed us to go to the moon), or the entire thing is a very tight-knit illusion. If the former is true, we’ve nothing to worry about. If the latter is true, there’s nothing we can worry about. We’re living in the matrix and there’s not a damn thing we can do about it. So we might as well carry on as if this world were real.

    1. Hi deat Tim,

      Yes I completely agree with what you say. I was not suggesting the world is not real, I was suggesting that the statement is not falsifiable. To know the world is not real we need another reality, and if that does not exist (and as we suspect the world IS real), then we can never know it.

      1. Yes, I understand that, but you were also saying (correct me if I’m wrong) that this presents some sort of problem for science, or some sort of problem with using falsifiability as a criterion for knowledge.

        But it doesn’t – at least not based on this example. “The world is real” is something we must take as axiomatic for everything else we believe. As I said, our only two choices are to accept this premise, or give up, so clearly we know which to chose. Once we’ve accepted the premise, falsifiability is a useful criterion for most things that can be considered knowledge.

        Or can you give other, practical examples where falsifiability is not a useful criterion?

  2. Well not a problem for science, but as a criterion of knowledge yes. If it is indeed a good criterion of knowledge it can work on every statement, no exceptions to the rule.

    If you remember it took me a long time to write this post, and the reason is I did not (and still do not) have access to my books back home (I may never have unfortunately). I read most of what came in this post in some books (This for example, or this, but the third part was unfortunately in one book which I do not remember, neither the name of the book nor the author.

    There were examples there, but although I do remember the main argument, I don’t recall them. I remember one example was about the Newtonian world view and the fact that it had non-falsifiable elements. Which elements I don’t recall. The author had also suggested Occam’s Razor to be added to falsification in order to make it a better criterion of knowledge. (I think my examples are good enough though in demonstrating what is wrong with falsifiability).

    It is very frustraiting for me when I don’t have access to what I had before, but that is the price I had to pay for more freedom.

    I would suggest if your intrested look at the above items and other problems of filsifiability as a criterion of knowledge. Particularly “How to Think About Weird Things” in which as I remember the authors explain why they do not choose falsifiability as a viable criterion of knowledge.

  3. Let me also add this: As I said before, if one takes Quine seriously, one realizes that by testing one theory, we are testing “all” the knowledge of humanity combined. Logic, Math, and things that are defined to be true are a part of that. They are also not falsifiable.

    But of course I for one am not utterly sure I should take him seriousely. Seems hard to believe by testing the concept of speed we are testing biology for example.

  4. Slightly on topic, but not wholly.. This is a video from one of RIchard Feynman’s lectures where he talks about the scientific method. He is up there for me as one of the brightest minds of the 20th c.
    Basically, the ‘Laws’ begin as mere tautologies. When there is a set of experience which we can relate the tautology to, we call it a law.

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