Interestingly, not everyone thinks that it is vital that we respond to the problem of induction by finding a way of resolving it. Instead, some argue that this is a problem that we can live with.
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Perhaps the most famous proponent of a view of this sort is Karl Popper (1902–94), who argued that the problem of induction was not nearly as pressing as it might at first seem because we don’t in fact make use of inductive inferences all that often.
In particular, he claimed that science, properly understood, does not make use of inductive inferences at all, but instead proceeds deductively.
In order to see what Popper means by this, consider again the inference that we looked at above concerning emus:
1* Lots of emus have been observed over many years and in a wide range of environ- ments, and they have always been flightless.
Therefore:
C All emus are flightless.
This is clearly an inductive inference since the truth of the premise is compatible with the falsity of the conclusion (i.e. the premise makes the conclusion likely, but does not entail it). Moreover, it also seems to accurately represent the way in which a scientist might go about discovering that all emus are flightless – that is, observe lots of emus in lots of different conditions and then draw a general conclusion about whether or not they can fly.
Karl Popper (1902–94)
Good tests kill flawed theories; we remain alive to guess again.
Popper (attributed) Karl Popper was born in Austria but spent most of his academic life working in Britain. His most famous philosophical contribution was the advocacy of the process of falsification as an alternative to induction when it came to understanding science. He claimed that the methodology of science was not to slowly and inductively build up a case for a generalisation, but rather to for- mulate bold generalisations and then seek to refute them by finding counter- examples to the generalisation.
Popper claimed that the mark of a scientific theory was that it was falsifiable – that is, that there was some observation or set of observations which would show that it was false. With this benchmark for what constitutes a scientific theory in mind, Popper argued against certain theories which purported to be scientific but which weren’t, Popper claimed, falsifiable. The two theories that Popper focused upon in this regard were Marxism and psychoanalysis. In both cases, argued Popper, any apparent counter-evidence to the view is always explained away so that nothing is ever allowed to count decisively against the theory. But that just goes to show, claimed Popper, that such views are not falsifiable and hence not scientific theories at all.
the problem of induction 103 Popper claims, however, that in fact science proceeds not in this inductive fashion at all but rather by making bold generalisations and then trying to falsify them (i.e.
by trying to show that the bold generalisation is false). When successful, this process is what Popper calls falsification. For example, to take the emu case just described, the scientist who suspects that all emus are flightless will boldly put forward this hypothesis for testing. ‘Testing’ the hypothesis, however, does not mean looking for evidence in its favour, but rather looking for decisive evidence against it. In this case, for instance, it will mean looking for an emu which can fly.
Notice the form of the inference that would take place if one were to falsify a hypothesis in this way – that is, if one were to discover a flying emu. First, we have our bold hypothesis:
H All emus are flightless.
We also have our definitive counter-evidence to H, the observation of a flying emu:
1 There exists a flying emu.
From this observation we can conclude that the bold hypothesis, H, is false, since this states that all emus are flightless:
C Not all emus are flightless.
What is important about this inference from 1 to C, however, is that it is entirely deductive, not inductive. If there does indeed exist a flying emu, then it follows deductively that not all emus are flightless; this conclusion is not merely likely, given the premise, but must be the case.
Popper’s idea is thus that by offering bold hypotheses which they then try to fal- sify, scientists are in effect proceeding deductively rather than inductively. That is, they do not try to find lots of evidence which supports, albeit inconclusively, the conclusion of an inductive inference; rather they make a bold generalisation which they then try to falsify conclusively, where if this falsification takes place, they can deductively conclude that the bold generalisation is false.
If Popper is right on this score, then it follows that we needn’t be quite as troubled by the problem of induction as we might have thought we should be, since it is not as if as much of our knowledge of the world – gained through science – is dependent upon induction as we originally supposed. But does Popper’s rather radical solution to the problem work?
There are a number of problems with Popper’s proposal; we shall here consider the two main ones. The first problem arises because if we understand our scientific knowledge in the way that Popper suggests, then it’s not clear that we have all that much scientific knowledge. As it happens, no one has ever observed a flying emu (as far as we know at any rate). Do we not know, then, that all emus are flightless? Not according to Popper. If we found a flying emu, then we could deductively come to know that not all emus are flightless, but knowing that all emus are flightless would
require induction, and recall that by Popper’s lights, we haven’t legitimated our use of that. It seems, then, that we can never know the unfalsified generalisations that scientists make; we can only know the falsity of those generalisations that have been shown to be false. Accordingly, it appears that we lose a lot of our scientific knowl- edge on the Popperian view after all.
The second problem with Popper’s proposal arises because it is not obvious that scientists are able to deduce the falsity of one of their bold generalisations simply by observing what seems to be a decisive counter-example to the generalisation.
Consider again the case of the emus. Suppose that for many centuries, people had observed that emus were flightless, and so came to believe that all emus are flight- less. Now suppose that one day a scientist comes into the room and claims that she’s just seen a flying emu. How would you respond?
One certainly wouldn’t abandon one’s belief that all emus are flightless just on the basis of this single instance of testimony. After all, given the long history of obser- vations of flightless emus, other explanations of what this scientist seems to have observed seem far more preferable. At the uncharitable end of the spectrum, one might suspect that the scientist was simply wrong in her observation, or perhaps even deceitful. Even if one trusts the scientist, however, there are still ways in which one could challenge the observation. One could note that there are birds in the area that can look a lot like emus in certain conditions. More radically, one might simply assert that whatever this creature was that was flying, it couldn’t have been an emu, since it is characteristic of emus that they don’t fly, and so it must have been a dif- ferent creature entirely, perhaps a new type of bird not seen before, one that is just like an emu in every respect except that it flies.
The crux of the matter is that one isn’t rationally obliged to take any observation at face value. In particular, there seems nothing essentially irrational about objecting to the observation in the sorts of ways just outlined, provided that the generalisa- tion called into question by the observation is sufficiently well confirmed by other observations. The problem, however, is that if there is rational room for manoeuvre regarding whether one accepts an observation at face value, then it appears as if there is even less scientific knowledge on the Popperian view than we thought, since, unless one accepts the observation at face value, one can’t make the relevant deduc- tive inference to the denial of the bold generalisation and so come to know that the generalisation is false. That is, the upshot of this objection is that not only does this view prevent us from knowing that any generalisation about the world is true, it also doesn’t follow on this view that we necessarily have much in the way of knowledge that many generalisations about the world are false either.