speaking hypothetically

える(たとえる) Hypothetically speaking, … For example: 泥棒の話に例えてみれば、(say, hypothetically, if you were a robber...)Hypothetically, if I had a friend, and if this, er, hypothetical friend happened to, say, have sex with your sister, how would you feel about this? Also, sometimes 例える has a second meaning:to liken something to something else. For example: He likened the unpopular president to a lame duck. 彼が首相のことをしにかかったアヒルに例えていた。
(そうぞうする) Imagine if... (蛸だと想像してください) (Imagine for a second that you’re an octopus, OK? Now,  what if. . . .) or, ‘Imagine if you won the lottery.’ Basically the same as 例える、 but the emphasis is on imaginative play rather than philosophy or moral ‘thought experiments’.
(かりに) Same as 例える、minus the ‘liken to’ angle.   $$$
Usually if you want to speak hypothetically, you’ll simply use the –ba form. Like this: もしxxxだったら、yyy. But there are some other, more formal ways to speak hypothetically, so here they are.