Therefore, all x are z. The existence of such reasoning patterns is fundamental in logic but raises important questions. Let us consider the first of these questions first. Obviously there are patterns that are just plain wrong in the sense that they can lead to incorrect conclusions. All x are y.
Some y are z.
Therefore, some x are z. Now let us take a look at an instance of this pattern. If we replace x by Toyotas and y by Japanese and z by made in america, we get the following line of argument, leading to a conclusion that happens to be correct. All Toyotas are Japanese cars. Some Japanese cars are made in America.