That the policy of nuclear deterrence has worked thus far is unquestionable. Since the end of the Second World War, the very fact that there were nuclear armaments in existence has kept major powers from using nuclear weapons, for fear of starting a worldwide nuclear exchange that would make the land of the power initiating it uninhabitable. The proof is that a third world war between superpowers has not happened.
Premise: Nuclear armaments in existence has kept major powers from using nuclear weapons, for fear of starting a worldwide nuclear exchange that would make the land of the power initiating it uninhabitable. The evidence for this is that no third world war has happened between superpowers yet.
Conclusion:Policy of nuclear deterrence has worked thus far is unquestionable.
We must find a flaw in the argument, something that weakens the conclusion that policy of nuclear deterrence has worked. So, something that shows policy has not worked and that the policy/ deterrence is not the reason for the nuclear war not happening.
(A) Maintaining a high level of nuclear armaments represents a significant drain on a country's economy: The argument already states that there were nuclear armaments in existence but they kept from using it because of the policy, so policy still works.
(B) From what has happened in the past, it is impossible to infer with certainty what will happen in the future, so an accident could still trigger a third world war between superpowers. - out of scope
(C) Continuing to produce nuclear weapons beyond the minimum needed for deterrence increases the likelihood of a nuclear accident.- again does not question the effectiveness of the policy, nuclear weapons are there but have not been used.
(D) The major powers have engaged in many smaller-scale military operations since the end of the Second World War, while refraining from a nuclear confrontation. - it still says that they have refrained form nuclear confrontation, that is what the policy intended to do.
(E) It cannot be known whether it was nuclear deterrence that worked, or some other factor, such as a recognition of the economic value of remaining at peace - this option casts a doubt on the effectiveness of the policy of nuclear deterrence. Probably there was a recognition of the economic value of peace which resulted in them not using the nuclear weapons. This provides an alternative cause for the conclusion and hence, must the correct answer.