You can get the taxes a company paid by going to www.sec.gov and reading their 10Q or 10K report, or you can go to their website and get their latest financial statement. Of course, this works only for publicly-traded companies, of which ExxonMobil is one.
Note however that Exxon is a multinational, and pays taxes all over the place, with various credits for various taxes. So whatever number you see at the bottom won't be what they pay to the IRS. In some countries, they may get credits (if they lost money in one particular country, they may get a NOL carryforward depending on the tax laws of that jurisdiction).
The notes to the financial statement may breakdown where taxes were paid.
It's really hard to believe the author is an economics professor. I would love to see this clown debate this issue with Dr. Milton Friedman, who would no doubt demolish the argument for "returning profits to the people." Doesn't the author know anything about the subject he teaches? Does he understand why Exxon-Mobil spends billions every year on the exploration and production of oil? They don't make all this effort to give the profits to charity.
It's also crucial to understand that while E&P and depreciation expenses are subtracted out before net income, profits ARE the source of cash for the huge capital spending requirements of today's oil projects.
