Final answer:
It is false that a contradiction cannot have a biconditional as its main connective; a contradiction is a statement that is always false, whereas a biconditional requires both parts to share the same truth value, and this alone does not constitute a contradiction.
Step-by-step explanation:
Answer B is correct, as it is false to assert that it's impossible to have a contradiction whose main connective is a biconditional. A contradiction is defined as a statement that is always false, specifically the conjunction of a statement and its negation. Now, a biconditional statement will be false if the two parts are not both true or both false; hence if one part is false, it forces the biconditional to be false, but this does not ensure that the entire statement represents a logical contradiction.
A contradiction must assert and deny the same thing, in the same respect, at the same time. A biconditional only insists that two statements have the same truth value, whether both true or both false. There may be scenarios where a contradiction could be at the core of a complex biconditional, but a mere biconditional relationship between two statements doesn't guarantee a contradiction. Moreover, we cannot ignore the possibility of a false premise leading to a seemingly contradictory biconditional, much like the 'false lemmas' described by Gilbert Harman, where an inference that leads to a true belief passes through false premises.