Before we turn to assessment of ontological arguments we need to get clear about what the proper intended goals of ontological arguments can be Suppose we think of arguments as having advocates and targets when an advocate presents an argument to a target the goal of the advocate is to bring about some change in the target What might be the targets of ontological arguments and what might be the changes that advocates of these arguments aim to bring about in those targets Here are some proposals no doubt the reader can think of others The targets might be atheists and the goal might be to turn them into theists The targets might be agnostics and the goal might be to turn them into theists The targets might be theists and the goal might be to improve the doxastic position of theists The targets might be professional philosophers and the goal might be to advance understanding of the consequences of adopting particular logical rules or treating existence as a real predicate or allowing definitions to have existential import or the like The targets might be undergraduate philosophy students and the goal might be to give them some sufficiently frustrating examples on which to cut their critical teeth In the coming discussion it will be supposed that the targets are atheists and agnostics and that the goal is to turn them into theists Suppose that an advocate presents an ontological argument to a target What conditions must that arguments satisfy if it is fit for its intended purpose A plausible suggestion is that minimally it should make the targets recognise that they have good reason to accept the conclusion of the argument that they did not recognise that they have prior to the presentation of the argument Adopting this plausible suggestion provides the following criterion a successful ontological argument is one that should make atheists and agnostics recognise that they have good reason to believe that God exists that they did not recognise that they have prior to the presentation of the argument Note that this criterion has a normative dimension it adverts to what atheists and agnostics should do when presented with the argument There is an important discussion to be had about whether we should suppose that the targets of ontological arguments are atheists and agnostics and that the goal is to turn them into theists However it is simply beyond the scope of this entry to pursue that discussion here