Is it true that a scientific theory can be refuted but never verified?

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Scientific Theory and the Scientific Method

Introduction

There are many methods that humanity uses in its quest for knowledge about our existence. Of the many methods used to justify our world views one of those is the ‘scientific method’. Due to its regular ‘success’ at determining information about how the universe works, the ‘scientific method’ has gained favour over the centuries. There have been many arguments put forward in regards to the ‘philosophy of science’. One of the arguments put forward is that a ‘scientific theory’ can be refuted, but never verified. How well does this claim hold up though?

Before assessing the claim we should first look at the ways in which we gather and gain information and knowledge. Knowledge and information can be gained in two ways. It can be gained in an a priori fashion, independent of experience and observation, and in an a posteriori fashion, through experience and observation. These two methods are also described as ‘deductive’ or ‘inductive’.

Deduction

A ‘deductive’ argument allows us to gain knowledge independent of experience. It is one in which if the premises are indeed true, then the conclusion must also logically be true. An example of a valid ‘deductive’ argument is as follows –

‘P1) All men are mortal.

P2) Socrates is a man.

C1) Therefore Socrates is mortal.’

Here we can see that conclusion is deduced from the previous premises, and therefore must logically be true. To deduce anything else from the premises would be logically invalid, to state that Socrates is immortal would be drawing a false conclusion. This is the major strength of the ‘deductive argument’. It offers a guaranteed amount of certainty to the knowledge drawn from the conclusion, so long as the premises it is deduced from are in fact true of course. What though of conclusions drawn from false premises?

An example of an argument which draws a true conclusion from false premises is as follows –

‘P1) All men are immortal.

P2) Socrates is a man.

C1) Therefore Socrates is immortal.’

Here we can see that the conclusion drawn solely from the premises is actually correct. If all men are immortal, and Socrates is a man, then it must logically follow that Socrates is immortal. However, premise one is false. Humans are not immortal, so therefore the conclusion drawn is in fact untrue. However, the only way we can know that this conclusion is false is through experience. It is through experience with humans that we know that men are mortal.

Deductions about nature

Which leads us to a problem with using ‘deductive’ arguments as a sole method of gaining knowledge about ‘nature’ or ‘reality’. We cannot be certain of their ability to accurately describe ‘nature’ or ‘reality’ without some form of experience of the premises. If the ‘deductive’ argument is being used to come to a conclusion about ‘nature’ we must use some form of ‘induction’, along with the ‘deduction’, in order to assess its potential to accurately describe ‘nature’ or ‘reality’. So does this mean that ‘inductive’ reasoning would be a more accurate and more effective way of guaranteeing accurate knowledge about ‘nature’ or ‘reality’? Can observation or experience guarantee us knowledge about events beyond the observation or experience? Can it even guarantee us that the knowledge gained from the observation or experience is correct?

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The problem of induction

‘Inductive’ reasoning allows us to take our experiences and observations and draw inferences based upon those experiences and observations. We often use these experiences and observations to give our lives some semblance of perceived order, and use these inferences to plan our day to day lives. These inferences are used in many different ways. We use them to draw inferences about events in the past as well as in the future. However, unlike the conclusions reached from a ‘deductive’ argument in which the conclusion logically follows from the premise, the inferences drawn from an ‘inductive’ argument cannot be guaranteed to logically follow from the premises. They cannot give us guaranteed accurate knowledge in the same manner in which a valid ‘deductive’ argument can.

Scottish philosopher David Hume argues as such in his Enquiry Concerning Human Understanding. He argues that the conclusions that we reach from experience and observation are not based on reason, but instead are based on experience. In his writing Hume uses an example of bread giving us nourishment (Hume in Cottingham, 2009, p434). It is because of our experience with bread giving us nourishment that we expect it to continue to give us nourishment. However, there is no good reason to assume that this will always be the case. Other factors, unknown and unpredictable to us, may interfere with the process, and render our conclusion invalid that the bread will give us nourishment. Our conclusion comes from probability based on our previous experience from eating bread, rather than reason.

There are many real world examples that show us that past experience cannot guarantee us accurate future results. Here we can take an example as simple as that of a watch or clock telling us the time. If we were to imagine owning a watch or clock, and that watch or clock has accurately told us the time for the entire length of our owning it. Every time we have observed the watch or clock, and matched the time against another accurate watch or clock, we have found the watch or clock to accurately match against the other. We may then infer that the watch or clock will always be accurate. However, unforeseen circumstances may render the watch or clock inaccurate. We could observe the watch or clock at 11:15, and then 60 seconds later observe it again and expect it say 11:16, however perhaps the battery could have ceased to function or perhaps parts unseen to the naked eye may have slowly worn down unknown to us and caused the watch or clock to run slightly slower than it should.

Just as we have experience of our watch or clock running accurately, so too do most of us have real world experience of watches and clocks running slowly or even ceasing to function altogether. Our experience of past events cannot guarantee us that same experience of future events, or even events in the distant past. Just because a volcano on an island in Hawaii has not erupted today, does not mean that it has never erupted or never will erupt. Where then does this leave us when it comes to gaining knowledge about ‘nature’ or ‘reality’? If ‘science’ is based upon observations made about ‘nature’ and ‘reality’, where does the problem of ‘induction’ leave the ‘scientific method’ and its ‘theories’?

Popper, science and falsification

Karl Popper, one of the most famous philosophers of science, approaches questions such as these in his paper titled ‘Conjectures and Refutations’ written in 1963. Popper’s main goal in writing the paper was to create a way in which ‘science’ could be distinguished from ‘pseudo-science’. So what is ‘science’ and what defines distinguishes it from ‘non-science’?

The disciplines of science are commonly seen as a set of disciplines that follow a particular method. This method is traditionally seen as ‘a method of gathering data from observation and experiment and of inferring laws and theories from it using induction’ . However, as we have seen, Hume put forward a strong argument for why the use of ‘induction’ is not wholly rational when it comes to predicting future events from past observations. Popper argues for why he believes this does not cause a problem for the sciences in his paper. So what is Popper’s answer to the problem of ‘induction’, and how to distinguish ‘science’ from ‘pseudo-science’?

Popper’s answer to this, to put it simply, was ‘falsifiability’. Popper’s idea is that the strength of a ‘scientific theory’ lies not in its ability to show how it is right, but rather in its ability to show how it can be wrong. He proposes that we should not set about trying to prove why a particular theory is right, for we can, in general, come up with data to support any idea. That as humans are a pattern seeking being we have a natural propensity to see supporting patterns in our observations when we set out to find them. It is suggested by Popper in his paper that we have a natural tendency to hold on to our ideas even when they appear to be wrong, that ‘we stick to our expectations even when they are inadequate and we ought to accept defeat’ (Popper in Cottingham, 2009).

Therefore the strength of a theory lies not in its attempt to find observations that support the assertions laid out by it, but rather in its attempt to find observations that would allow us to dismiss the assertions laid out in it. It is the ‘critical approach’ to examination that allows us to get closer to knowledge rather than a ‘dogmatic approach’. Popper states that this does not mean that we should dismiss all observations that support a theory. Rather that confirmations and supporting observations should only be considered ‘if they are the result of risky predictions, that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory – an event which would have refuted the theory’ (Popper in Cottingham, 2009, p455).

It is also suggested by Popper that a good ‘scientific theory’ should not start its point of argumentation from observation, or ‘inductive’ reasoning, but rather that a good ‘scientific theory’ should start its point of argumentation from ‘deductive reasoning’. For it is ‘only by purely deductive reasoning is it possible for us to discover what our theories imply, and thus to criticise them effectively’ (Popper in Cottingham, 2009, p458). If we are to take the example used in our explanation of ‘deductive reasoning’ at the beginning of this paper, that ‘All men are mortal’. Popper suggests not that we seek out examples of ‘mortal men’, rather that we seek out examples of ‘immortal men’. For the strength of the conclusion comes not from our ability to show that there are ‘mortal men’, but from the strength of our ability to show that there exists no known cases of there being men who are not mortal.

However, Popper also suggests in his paper that these conclusions should only be held tentatively, and that we should never rest on our laurels. That we should actively continue to seek out examples that disprove our ideas, even if ‘we feel unable to doubt them any longer’ (Popper in Cottingham, 2009, p459). For, as the problem of induction shows, we can never be certain that there has not, is not, and can never be, an example that disproves the conclusions we reach from our ‘deductive’ reasoning.

Conclusion

It is for these reasons that, if we are to take Popper’s argument for what defines a ‘scientific theory’ and sets it aside from a ‘pseudo-scientific theory’, that we cannot prove a ‘scientific theory’ to be true. That the answer to the question is indeed ‘yes, it is true that a scientific theory can only be refuted and never verified’.

If proper procedure as laid out by Popper is followed, then the intent is not, and should not, be to show the theory is correct. The proper procedure is to show that it is not correct, and to hold tentatively to the theory so long as it has not been shown to be incorrect. Could we not argue that this is one of the strengths of the ‘scientific method’ though? That its strengths lie not in its ability to claim it is correct, but rather in its ability to show that it has not been shown to be incorrect, and its willingness to accept, even when it appears to be beyond doubt, that in the future some new information could come to light that shows it to be incorrect?

References

Hume, D. ‘The Problem of Induction’ (2008 [1748]) in Cottingham, J. Western Philosophy:An Anthology, Oxford, Blackwell Publishing, pp. 433-437.

Popper, K. ‘Science and Falsifiability’ (2008 [1963]) in Cottingham, J. Western Philosophy:An Anthology, Oxford, Blackwell Publishing, pp. 453-459.

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