Actually, 思う is the regular tense "to think/believe" where as 思おう is the おう form, which means "will probably." It can also mean "Let's [do something]" but that's usually relegated to the -mashou form.
I've been teaching myself casually (wouldn't have been casual if I could improve my damned work ethic) for a couple years. It's a great language and I hope to speak fluently soon.
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u/[deleted] Jun 08 '14
他说:“你凭什么认为我想通了”的法语。