Step 3. Assume all premises are true and follow the consequences
Another way one can analyze an argument is to actually consider what conclusion follows from the original premises on your own. Do you conclude the same thing as the author of the argument? Why or why not? Consider the example of our first argument given above:
It is a good idea to make sure you have working fire alarms in your house. Just look at the family whose house burned down on Christmas. They lost everything in their house, and almost lost their daughter who nearly died of smoke inhalation. Their house did not have working fire alarms, and for that reason, the fire itself went unnoticed while the family slept. They were saved only by the chance occurrence of a neighbor's teenage son arriving home late from a Christmas-eve date who noticed the fire and woke the family up.
Here one may argue that given the truth of these premises, one should conclude not that it is just a good idea to have working fire alarms in your house, but rather it should be illegal not to have them. Notice that concluding that "it should be illegal not to have fire alarms" is to argue another conclusion that is different and more forceful than the original which just states that it is a good idea. Since it is not immediately clear that someone who does this is arguing for the conclusion (by adding an additional condition, "not only is it a good idea, but it should be illegal not to have them), or against it, (it is not a merely a good idea, but should be illegal…), we first note the following tip and then consider two special cases:
Tip 4. When analyzing an argument, consider other conclusions which follow from the truth of the premises which may not be included in the original argument.