Informally, a statement is falsifiable if some observation might show it to be false. For example, "All swans are white" is falsifiable because "Here is a black swan" shows it to be false. Formally, it is the same, except that the observations used to prove falsifiability are only logical constructions distinct from those that are truly possible.
Falsifiability differs from verifiability, which was held as fundamental by many philosophers such as those of the Vienna Circle. In order to verify the claim "All swans are white" one would have to observe every swan, which is not possible, whereas the single observation "Here is a black swan" is sufficient to falsify it.
It was introduced by the philosopher of science Karl Popper in his book The Logic of Scientific Discovery (1934), as an answer to both the Problem of Induction and the Demarcation Problem. He saw falsifiability as the cornerstone of critical rationalism, his theory of science.
As a key notion in the separation of science from non-science, it has featured prominently in many scientific controversies and applications, even being used as legal precedent.
Questions to be considered and debated:Popper noticed that two types of statements are of particular value to scientists. The first are statements of observations, such as 'this is a white swan'. Logicians describe such statements in terms of existential quantification, since they assert the existence of some particular thing. For Popper, such statements form the empirical basis of scientific theory. The second type of statement of interest to scientists categorizes all instances of something, for example "All swans are white". Logicians describe these in terms of universal quantification.
One of the questions in Scientific method is: how does one move from observations to laws? From an existential statement to a universal statement? This is the problem of induction. Suppose we want to put the theory that all swans are white to the test. We come across a white swan. We cannot validly argue from "here is a white swan" to "all swans are white"; doing so would be to affirm the consequent.
Popper's solution to this problem is to flip it upside down. He noticed that while it is impossible to verify that every swan is white, finding a single black swan shows that not every swan is white. We might tentatively accept the proposal that every swan is white, while looking out for examples of non-white swans that would show our conjecture to be false. This is the basis of critical rationalism.
Falsification uses the valid inference modus tollens: if from a statement P (say some law with some initial condition) we logically deduce Q, but what is observed is neg Q, P is false. For example, given the law "all swans are white" and the initial condition "there is a swan here", we can deduce "the swan here is white", but if what is observed is "the swan here is not white" (say black), then "all swans are white" is false, or it was not a swan.
1) Did the method by which a specified theistic belief was acquired adhere to the principle of falsifiability as described above?
2) If the method of theistic belief formation did not adhere to the principle of falsifiability, what other accessible and logical mechanism would demonstrate if a specified theistic belief is false?
3) When there is no accessible and logical mechanism for determining if a specified theistic belief is false, what is the justification for acquiring and defending this belief given that it places the representative apologists in the impossible position of never having an ability to determine if the belief is mistaken?
