Published online by Cambridge University Press: 18 December 2008
Opinions assume a paradoxical character in many speech events. The speaker, by sincerely presenting his views on a topic, is expressing his belief in a proposition, and this belief must be regarded as indisputable. If a speaker says that marijuana should be legalized, one cannot deny the speaker's belief in this proposition. He has expressed an opinion. The proposition, however, may itself be the topic of dispute. Another speaker may disagree by expressing his belief that marijuana should remain illegal, and a dispute regarding the validity of each of these propositions may ensue. Neither of these propositions is subject to proof or disproof, but the speakers may attempt to support them in order to add to the validity of the propositions and substantiate their beliefs.