A similar effect occurs with general knowledge. On the whole, if we’re faced with a choice of giving up a general principle or giving up a particular, but alleged, fact, then we abandon the alleged fact. We know that water freezes into ice. We have many reasons to believe this proposition. It fits with our other beliefs about winter, refrigerators, and mountaineering, and we have many observations to support it. Hence, if someone tells us: I froze some water, but it didn’t turn into ice. We tend to doubt the claim that they froze water rather than the general principle that freezing water turns it into ice.
Is there perhaps an effect of the form of propositions? Some psychologists believe so. Suppose someone tells us:
If it was raining then Pat went to the cinema. It was raining.
Given a conflict, because Pat didn’t go to the cinema, which of these two propositions do we give up if they are equally entrenched? Suppose someone tells us:
Either Viv was late or else she didn’t go to the cinema. Viv wasn’t late.
Given a conflict, because Viv did go to the cinema, which of these propositions do we give up? The psychological evidence suggests that we tend to give up the conditional in the first case, and the disjunction in the second case. What is odd, however, is that conditionals and disjunctions are consistent with more possibilities than categorical propositions, and so they have a greater probability of being true. One reason for our judgment may be that we believe that speakers are less likely to be wrong about simple categorical facts. Their truth can be a matter of observation rather than inference. Hence, categorical propositions have an aura of certainty lacking from more complex assertions about relations between propositions.
Can someone please expound why the emboldened sentence is true?