Popper: Conjectures and Refutations

What is the ultimate source of knowledge? If knowledge is what we seem to be continually striving for shouldn’t we have in mind a good idea of how we attain it. Do we get it from our senses, some higher authority, direct observation, tradition? In this book Popper unasks this question declaring that there is no ultimate source of knowledge, but instead a journey of continuously trying to eliminate error.

To repeat, the question of how do you know something is incorrectly put. You do not, and can never, know something to be true, you cannot give an ultimate source. How we approach knowledge is therefore through a process of critical rationalism, you never ‘know’ something, you merely guess and see in what ways your guess will be falsified. 

Observations theory VS theory observations

Where does Popper differ from most of his predecessors? The main point of contention is whether we move from a set of observations to a theory or a theory to a set of observations? The first proposition might seem more in line with your own experience. After all if you think back to something as straightforward as a school science lesson you often will have stood around, collected measurements and then from those tried to come up with some pattern or some theory. But Popper would say that you have it all backward, what we actually do is come up with some plausible theory and then use a set of observations to see if we can falsify it. 

You’re even doing that sneakily in your science class without being told. Why would you be looking at things like spring extension vs mass in the first place if you didn’t have some implicit theory that there was a link. The world is simply too vast and there are simply too many observations you could make for you to discern anything out of it without a guiding theory pointing you in which directions to look.

Instead of theories being the result of accumulating observations Popper puts forward that observations are the result of accumulating theories. We do not wait for the world to reveal its patterns to us over time, instead we try to impose our patterns onto the world and we see how well they fit. If one fits better than the last pattern we adopt it as our banner, fully knowing, or at least hoping, that it too shall soon be replaced by something even better.

Popper gives a particularly detailed example of when our intuition has been lead astray with Isaac Newton. To many people his ideas are a perfect example of observation → theory, Popper gives us three reasons why we’d be wrong.

The idea that Newton came up with his particular ideas based solely off observation isn’t intuitively credible. To start with all observations are always inexact whereas Newton’s theories make perfectly exact predictions, not only that but they have been verified to a level of exactness that Newton  would simply not have been able to use for any observations in his day. To think we can derive a more exact theory from less exact observations by logical means only seems unlikely. 

Popper’s second reason why observations did not lead to theory is that this idea is historically false. Like all his predecessors Newton carried out experiments to test ideas. Kepler did not derive his laws simply from the observations Tycho Brahe made. Instead he thought the orbits of planets were circular and this was refuted by the measurements, then he thought they may be elliptical and this was born out. This did not prove his theory to be correct, for this cannot be done, but rather his theory allowed an explanation that was inline with what was observed. This is similar to the process Newton went through, he did not have new observations to work with as much as new interpretations.

Popper’s third reason to refute that Newton’s theories were created from a set of observations is that it is not logically possible. The proof of this comes from Hume and works something like this:
1. No logically possible observation can ever contradict the class of all past true observations. i.e stuff that happens in the future and stuff that happen in the past are part of the same reality so can’t contradict each other.
2. If we can join a statement (x) without contradiction to a class of statements (y), then that one statement (x) can also be conjoined to any class of statements (y) and any statement that can be derived from (y).
3. So if Newtons theory could be derived from the class (y) of true observations then no future observation would ever be able to contradict it.
4. If Newtons theories tells us something that we cannot derive from past observations (y) then it cannot be logically derived from observation only 

The Greeks and the beginning of science

How we came to be able to reason like this is something Popper spends time investigating on our behalf. To him this ability traces its roots back to the Greeks. In this period we managed to move away from a world ruled by myth and reference to higher authority and towards one that we inspected through our own senses and experiences.

One of the main shifts was that a tradition became established of not just accepting the reasons for how something functioned but criticising them and seeking better explanations, the Greeks literally invented discussion. What this lead to was science, which Popper is quick to point out is not as far from myth as we may think. Science is differentiated not by being distinct from myth but by being accompanied by the second order tradition of critically discussing the myth in question.

This period of time also provides fertile ground for the idea that observations don’t lead to theory. Many proposed theories of the age were little more than slightly different myths. Myths that would be very difficult to come up with based on a chain of reasoning that started from observations alone. 

Contradictions and edging closer to knowledge

What does the system Popper puts forward as our method of accumulating knowledge look like then? It seems to run something like this, you start with a theory in mind that can explain everything we have currently observed and that makes predictions that are testable. Every proper theory must make predictions that prohibit certain things from being expected and should lead us to expect things will happen that we would not expect if we were not in possession of the theory.

We then make observations based on what we’d expect from the theory. If they match what is predicted we hold onto the theory for a bit longer, testing other predictions. If not we find ourselves at a contradiction, something that should be one way based on the theory and is a different way in real life. This heralds the direction for us to proceed on.

we move from one theory to another, each patching the contradictions of the previous theory and each having new contradictions themselves

To Popper, and many others, criticism and contradiction are the keystones of how we progress. We criticise a theory until we find a contradiction. The benefits of contradiction however comes from our decision not to tolerate them. They are at once destructive and creative and must always be both, they destroy the credibility of the theory they are part of but they create the path for us to come up with out next theories. As Marcus Aurelius says:

“what stands in the way, becomes the way”

What we end up with is what Popper calls the searchlight theory of science. Each new theory patches holes in the previous theory while positing new things that the last theory couldn’t shed light on. Each new answers begets new questions, you can’t become curious about quarks until you have a theory that posits the existence of atoms.


Popper’s views on society share the underlying theme of ‘if we can never know certain truth all we can hope to do is to find ways of identifying and remedying our incorrect theories’. It is all about inverting the question from how do I do right to how can I detect and correct the wrong. For example, we should not try to have the best institutions but rather have a situation where bad institutions and bad people can only be of minimal damage. To strive for the best institutions is like striving for absolute truth, something we can never reach and that can lead us astray. In a more abstract sense we should try to eliminate concrete evils rather than the realisation of some abstract good, or in his words:

“Do not allow your dreams of a beautiful world to lure you away from the claims of men who suffer here and now”

To Popper’s mind following the dreams of a beautiful world and the moral enthusiasm this engenders could be forces of real danger. Why is moral enthusiasm dangerous? It is that the world we live in is complex and we understand so little of how it works, to become overly confident in any view on how it should work, which is what moral enthusiasm does, can lead you to trying to fit the world to a model that is not right.

His views on tolerance seem mainly inspired by his devotion to the idea and tradition of criticism and discussion. He holds the Greeks in incredibly high regard for they were the first to openly tolerate questioning the world around them and look for better answers. What he sees as a great evil then is intolerance, for intolerance risks diminishing our ability to question the world around us and therefore to learn about it. It would be cutting us off at the intellectual heel. For this reason he espouses a view of tolerance to all things except intolerance otherwise known as his paradox of tolerance.

Social Science

Before we look at what Popper says on social science I want to pause to consider his views on the difference between social science, and most other areas of study, to science. In science we criticise theories, find errors and systematically attempt to correct them. This allows us to make progress, we can almost unequivocally say that we are using better science than we were in 1800 and they will almost certainly have better science than us in 2100. In almost all other disciplines however it is not just that progress can be difficult to achieve it is that we struggle to even evaluate change. 

This being the case, and in keeping with his style, Popper is quick to tell us what social science isn’t rather than what it is. In this he gives us two false ways of using or practising social science.

1. It shouldn’t be about studying the behaviour of social wholes e.g nations or classes. This is because these groups don’t really exist, they are like platonic ideals. You can talk about ‘the middle class’ but you can never point to a discrete group of people who make it up. People fit in too many groups and have too many different reasons for acting in ways for you to ever be able to make theories that rely on some fixed group of them. Instead what you should do is to analyse everything from the individual level based on incentives because this is the only level at which you can talk about people acting as a whole unit.

2. The second thing social science is not about is trying to explain things in terms of conspiracy. Popper sees too many people as believing that the world around them is the way it is because of some small group of powerful people conspiring to make it so. He dismisses the idea as untrue and says that even if it was likely that a group of people tried to act in this way it would not be worth looking into much. The people who would try to influence the system would change the very system they are trying to influence leading to unintended consequences for them. The systems we live in is reflexive, our actions try to influence the system but are also influenced by the system, for this reason clear chains of cause and effect can be very difficult to ever unravel.

So what does Popper see the role of social science as being? It is to explain the things that no one wants, the unintended consequences of our actions. Almost no one benefits from a war or depression and yet they happen. This again relates back to his philosophy that we need to look at figuring out how things are wrong rather than how to work towards some higher goal. The iterative elimination or understanding of unwanted events will move us towards a better outcome even if we don’t know what that outcome is. Trying to understand why good things happen or how we can achieve these is like trying to find ‘perfect truth’ which we can never achieve.


Popper’s philosophy is one of pragmatism and humility. He sees no reason to pursue philosophical problems that do not come from areas outside of philosophy. Philosophy and science should be about understanding the riddles of the world, not about asking what is philosophy or what is science. As far as humility goes his doctrine is one of our fallibility and ignorance. We cannot achieve perfect knowledge only strive towards being less wrong and we should keep in mind that we are all equal in our infinite ignorance, or as Xenophanes said:

“The gods did not reveal, from the beginning,
All things to us; but in the course of time
Through seeking we may learn, and know things better”

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