Ergo Sum was a science fiction fanzine published by Paul Wyskowski.
Ergo Sum was published in the 1970s in Ottawa, Ontario, Canada. It had previously been named Differential, and under that name 37 issues had been published, from September 1962 till August 1965, After a break the editor began publishing again, with the new name but retaining the same numbering of issues, so that the first issue of Ergo Sum was #38. The last issue was #41.
The fanzine featured fiction, news, commentary, and two pages of poetry.
Contributions came from E.E. Evers, Sharon Towle, and editor Paul Wyskowski.
Paul Wyskowski had been a fan since the 1950s when he was contributing to Norman Browne's Vanations. Later in the 1970s, he did an apazine called Blind Starling.