Case 2. Explore the most probable consequence(s) of an assertion.
This method is very common in philosophy, especially so in Ethics. It is similar to the reductio ad absurdum, but instead of each step in the process being a valid inference we only demand that the new step follow with a degree of high probability. In turn, if this process leads to a conclusion that seems for independent reasons highly improbable or undesirable, then the truth of the original claim is cast into doubt. Clearly this is not as strong as the reductio ad absurdum method previously mentioned, but as that method can not always be used, this provides a useful alternative. Here is an example taken from Ethics. We will use this method on the following claim : The rightness or wrongness of an action is determined solely by the individual.
Suppose that the rightness or wrongness of an action is determined solely by the individual. This would imply that for some people, stealing might be deemed ethical, even if you personally feel it is not ethical. This in turn means that you have no justification – other than your own personal ethical code – to condemn someone who robs you and feels it is ethically permissible to do so. This consequence, namely being unable to condemn the action of someone who robbed you universally, is so undesirable in and of itself that it casts doubt on the original claim that the rightness or wrongness of an action is wholly determined by the individual.
Notice that the conclusion in each step is not guaranteed but seems to be likely. The end state of affairs where one is unable to condemn someone else for robbery is so undesirable that it casts doubt on the original assumption that the rightness or wrongness of an action is determined solely by the individual.
This second approach (case 2) has problems too. It may be the case that another analysis of probable inferences results in a conclusion which is probable and desirable. When this happens, all that can be done is to try to decide which chain of probable inferences is most likely. And deciding what is most likely -even with past cases as a guide - is so difficult that it even has a name and represents another problem in philosophy called the "problem of induction".
It may be the case that one attempts to argue this way, but instead of each step being likely each step is unlikely - in this case we call the reasoning process a slippery slope fallacy, which brings us to our next method of argument analysis which is an examination of logical fallacies.
The following illustrates this second method of reasoning: