Can Arminians be trusted?

T’s Ability to Deceive 

Faulkner 2000 argues that the fact that testimony comes from a person, rather than an inanimate object, is a reason to be more demanding on testimonially-based beliefs than on perceptually-based beliefs. Lackey 2006a:176 and 188 n.44 also endorses this argument. People like T can lie, but the matter in our perceptual environment cannot. See also Audi 2006:40: “[T] must in some sense, though not necessarily by conscious choice, select what to attend to, and in doing so can also lie or, in a certain way, mislead … For the basic sources, there is no comparable analogue of such voluntary representation of information.” 

One way to make the point more precise is to claim that because free actions are particularly indeterministic—that is, because determinism is false, and so the past plus laws is not enough to guarantee future free actions—the environment for a testimonially-based belief cannot be regular and law-governed in the way that the environment for a perceptually-based belief can be. Graham 2004 considers such an argument in detail. He argues, however, that the presence of human freedom in testimonial cases is not a significant reason to prefer a conservative approach. He argues that if a libertarian approach to human freedom undermines the predictability of human actions, then it would also undermine a conservative approach to testimony; if T’s actions were unpredictable, then S could never have a proper basis on which to believe that T is likely to be honest, for instance. However, Graham argues that if libertarianism does not undermine predictability—either because it is false, or because counterfactuals of freedom are nonetheless somehow true—then testimonial liberalism is not threatened by human freedom, because the environments for testimonially-based beliefs can in fact be as predictable as the environments for perceptually-based beliefs. 

http://www.iep.utm.edu/ep-testi/#SSH2b.i