Fernando's favorable attitude toward capital punishment began to change when he was asked to offer arguments opposing it in a class debate. His attitude is best explained by theory.

cognitive dissonance theory

Explanation:

Cognitive dissonance theory -

It refers to as the condition involved in some conflicts of beliefs , behavior or ideas , is referred to as cognitive dissonance theory .

The condition gives rise to problem and confusion in the state of mind for the thoughts .

The most common example is , people who smokes , and are aware that smoking causes cancer , and hence are in a state of cognitive dissonance .

Hence , from the given scenario of the question ,

The correct answer is cognitive dissonance theory .