Here’s a simplified version of the sentence I'm working on.
Despite what he believed — or thought he believed — he still had to contend with the truth.
Or should I use commas?
Here’s a simplified version of the sentence I'm working on.
Despite what he believed — or thought he believed — he still had to contend with the truth.
Or should I use commas?
There is no rule that prohibits the use of or to isolate clauses in your interrupting phrase:
A word group (a statement, question, or exclamation) that interrupts the flow of a sentence and is usually set off by commas, dashes, or parentheses.
Note: there are rules for using dashes, parentheses, and commas. See parentheses vs. double commas vs. dashes for additional details.