Monday 21 March 2022

Does Popper’s Falsification Principle Itself Need to Be Falsifiable?

The logic of homological and heterological statements — as they relate to Popper’s Falsification Principle.

The Falsification Principle was first articulated in Karl Popper’s book The Logic of Scientific Discovery, which was published in 1934. In that book, Popper argued that a scientific theory (or hypothesis) is falsifiable if it can be logically (note that word) contradicted by an empirical test which can be — at least potentially — executed using existing technologies. Thus the main purpose of falsifiability is to make the scientific theory testable and predictive.

Popper used his Falsification Principle against (to cite only two examples) Sigmund Freud’s theories as well as against the claim that there may be — or actually are — infinite universes. Indeed the Principle has now almost become a commonsense theory — at least when used by (some) scientists and those laypersons who’re scientifically-minded.

Introduction

The following isn’t an essay on the nature of science itself or on scientific theories. It deals, instead, with a logical issue. (Perhaps an issue in the philosophy of logic.) This means that it won’t cover the vast tracts of criticism — and also support — of Karl Popper’s falsificationism.

These criticisms of the Falsification Principle are mentioned because many philosophers have taken much delight in “debunking” Popper’s falsificationism. Perhaps this is largely because such — mainly analytic — philosophers don’t care that much about the broad spirit and normative nature of the Principle; and so, instead, they look for “counter-examples”, etc. to it.

In any case, this essay is about the logic of homological and heterological statements; as well as about the relation between first-order statements and second-order (or meta) statements.

But, firstly, let’s get one thing straight out of the way.

Popper’s Principle is Not Itself a Scientific Theory

Popper’s Falsification Principle is… well, a principle, not a theory — and it’s certainly not a scientific theory. This simple fact will impact on the many claims that the Principle is (as one philosopher put it) “self-referentially contradictory and self-defeating”.

This line of attack goes back to the Hungarian philosopher Imre Lakatos (1922–1974), who once asked Popper if his own Principle was itself falsifiable. More precisely, Lakatos asked Popper the following question:

“Under what conditions would you give up your demarcation criterion?”

[See demarcation problem.]

Yet because the Principle is about scientific theories (i.e., the Principle isn’t itself a scientific theory), then claims that it’s self-referentially contradictory and self-defeating may not actually carry much weight. And this, in turn, may mean that these claims against Popper’s Principle are loosely equivalent to arguing that a painter who states that “All composers are evil” must himself be evil.

Indeed the failure to make this kind of distinction is summed up by the science journalist John Horgan when he recalled his own interview with Karl Popper.

Firstly, Horgan quoted Popper when he wrote the following:

“[]‘The first thing you do in a philosophy seminar when somebody proposes an idea is to say it doesn’t satisfy its own criteria. It is one of the most idiotic criticisms one can image!’[].”

And then Horgan added his own take on this issue:

“Falsification itself is ‘decidedly unempirical’; it belongs not to science but to philosophy, or ‘metascience’, and it does not apply to all science. Popper was admitting [] that his critics were right: falsification is a mere guideline, a rule of thumb, sometimes helpful and sometimes not.”

Finally, Popper’s Falsification Principle — or its expression as a single statement — can be taken as either being homological or heterological in nature.

Are Second-Order Statements Heterological or Homological?

A homological (in this case) statement is one that applies (or refers) to itself. On the other hand, a heterological statement (or sentence) is one that doesn’t apply (or refer) to itself.

The statement to be considered in the following may well fall into the latter category.

Despite that, Popper’s Principle is still taken (at least provisionally) to be a statement that’s possibly homological (or self-referential) in nature.

Popper’s Falsification Principle states that all scientific theories must be open to (possible) falsification. The obvious question to ask now is:

Can Popper’s Falsification Principle itself be falsified? Indeed is it even falsifiable in principle?

If the Principle can actually be falsified, then isn’t it invalid or simply false? If it’s falsifiable only in principle, then it may simply be self-defeating rather than false. On the other hand, if the Principle can’t be falsified or isn’t even falsifiable in principle, then isn’t it simply self-contradictory?

In addition, if Popper’s Principle can be falsified, this may well mean that there are indeed some scientific theories which can’t be falsified or which aren’t even falsifiable in principle. More clearly, if Popper’s Principle were actually falsified (though, again, Popper demanded falsifiability in principle, rather than an actual falsification), there may be — by implication — genuine scientific theories that are in principle unfalsifiable. On the other hand, if Popper’s Principle weren’t falsifiable, then it would be exempting itself from its own (seemingly) universal claim. Again, in order for Popper’s Principle to be falsifiable in principle, it may imply — or even entail — the existence of at least one genuine scientific theory that’s not falsifiable in principle. Indeed how else would the falsification theory itself be either falsifiable in principle?

Would that mean that if these non-falsifiable and non-falsified scientific theories actually exist, then Popper’s theory would be either useless and/or self-defeating?

If Popper’s Principle were falsified (rather than it being simply falsifiable in principle), then that would mean that it’s (simply) false. (Though, as stated in the section earlier, a normative principle can’t be either true or false.) And if it’s false, then what it claims is also false. And it claims that all genuine scientific theories must be falsifiable in principle. Therefore if what the Principle claims is actually false, then it’s also false that all genuine scientific theories must be — or are — falsifiable in principle. So Popper loses on both counts. If his Principle isn’t falsifiable in principle, then it can be deemed to be self-contradictory. On the other hand, if it can be actually falsified, then what it claims isn’t true.

Nevertheless, is it correct to argue that if Popper’s Falsification Principle can’t itself be falsified, then it must be invalid, self-contradictory and/or self-defeating?

According to Popper himself (though not, however, according to the falsifiability statement alone), no scientific theory is ever completely certain or completely true. Therefore Popper might have happily accepted the limited applicability of his own Principle (despite its seemingly universal nature). Of course Popper’s Principle can be given an absolute or axiomatic (i.e., rather than normative) status. And, if Popper had done so, then he might have allowed his Principle an escape which he denied to all scientific theories.

Conclusion

To recapitulate a little.

Karl Popper argued that scientific theories must allow the possibility of their own falsification; though he never — obviously — demanded their actual falsification.

So is Popper’s Principle of falsifiability itself falsifiable in principle?

If it isn’t, then it may be self-contradictory. On the other hand, if it can actually be falsified, then it may be self-defeating or simply useless.

Moreover, if Popper’s Principle can be falsified (or even if it’s only falsifiable in principle), this would entail the possibility — or even the actuality — that there are at least some genuine scientific theories which can’t be falsified or which aren’t falsifiable in principle. In other words, in order for Popper’s Principle to be open to being shown to be falsifiable in principle, then at least some scientific theories may — or must — be unfalsifiable in principle. On the other hand, if Popper’s Principle isn’t falsifiable in principle, then Popper might have been exempting his own Principle from its own universal claim about all (genuine) scientific theories..

Yet, as stated, the Falsification Principle itself isn’t a member of the set of scientific theories in that it’s a normative principle, not a scientific theory.