Consider the following premises. For all x_6, if x_6 drinks water, then x_6 is writing a letter. There is at least one x_6 for which x_6 will not write a letter. For all x_6, x_6 will drink water or x_6 is a janitor. For all x_6, if x_6 were a janitor, then x_6 is writing a letter. Can we infer the following from them? For all x_6, x_6 is not an artist.
 From the fact that for all x_6, if x_6 drinks water, then x_6 is writing a letter, that for all x_6, if x_6 were a janitor, then x_6 is writing a letter, and that for all x_6, x_6 will drink water or x_6 is a janitor we can infer that for all x_6, x_6 will write a letter. From the fact that for all x_6, x_6 will write a letter we can infer that for all x_6, x_6 will write a letter or x_6 is an artist. Finally, from the fact that for all x_6, x_6 will write a letter or x_6 is an artist, and that there is at least one x_6 for which x_6 will not write a letter we can infer that there is at least one x_6 for which x_6 is an artist, which contradicts that For all x_6, x_6 is not an artist. Therefore, the answer is no.