Chapter Five
suggests that false doctrines in the “marketplace of ideas” may not be as benign as is often assumed. Indeed, normal individuals are prone to misleading information, propaganda, fraud, and deception, especially in situations where their cognitive resources are depleted. In our theory, the more effortful process of disbelief
5.2 Contradictory Claims
true; it may also be the case that they are all false. But if the claims contradict, then it cannot be the case that they are all true at the same time. This is perhaps the easiest and most obvious situation in which you have good grounds for reasonable doubt. Here are a few more examples:
(to items initially believed) is mediated by the vmPFC; which, in old age, tends to disproportionally lose
“The stars in the night sky are actually pinpoints of light
structural integrity and associated functionality. Thus,
shining through little chinks in a cinder-block wall
we suggest that vulnerability to misleading information,
which surrounds our solar system.”
outright deception, and fraud in older persons is the specific result of a deficit in the doubt process which is mediated by the vmPFC.” 12
And with that observation in mind, let’s get underway.
You probably should not accept this claim because it conflicts with just about everything scientists around the world have discovered about the stars. “There are sharks and piranha fish living in the Ottawa river.”
5.2 Contradictory Claims Suppose, for example, you log into your favourite Internet social network, and you get a ‘friend’ invitation from someone famous. Just pulling a name out of the blue, let’s say it’s from Matt Smith, the actor who currently stars in the BBC sci-fi television series ‘Doctor Who’. The ‘proposition’ you are asked to believe, in this situation, is that the person asking to be added to your list really is the actor he says he is. But you probably have another proposition in your mind which states that famous people do not send requests like that to people they do not know. These two propositions cannot both be true at the same time. They contradict each other. So what you have to do is decide which one you have greater reason to believe, and which one you have greater reason to doubt. In this example, you have much greater reason to believe the second proposition. It’s much more consistent with other things that are well known about celebrities. And you have some excellent alternative ways to explain who might really be trying to ‘add’ you: a friend of yours who wants to play a practical joke on you, for instance. Or it might be a salesman, or a con artist. Contradictory claims are two (or more) propositions which cannot both (or all) be true at the same time. It might be the case that one of them is
This claim conflicts with a few basic facts about sharks and piranha, and about geography, which are easy to find out. Sometimes you might be given two statements that don’t contradict any practical knowledge you have about the world, and that don’t contradict your world view, but they do contradict each other. For example, consider these two statements: “Next summer, Heritage College will receive a multimillion dollar extension. When the work is done, our building will be twice as big!” “Next summer, the Heritage College building will be demolished and replaced with another, brand new, much bigger building.”
Either one of these statements might be true, and they are both fairly consistent with other things that you might know about the building, such as that it is slightly over-crowded, etc. But they clearly cannot both be true at the same time. So, in this situation, you should doubt both of them, and then ask a few teachers or administrators what they might know about the situation. Contradictory claims are one of the ways you can
12 Asp, Manzel, Koestner, Cole, Denburg, and Tranel. “A Neuropsychological Test of Belief and Doubt: Damage to Ventromedial Prefrontal Cortex Increases Credulity for Misleading Advertising” Frontiers in Neuroscience, 2012; 6:100. 9th July, 2012.
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