A formal synonym for “for some reason” could be “for a particular cause”. This phrase implies that there is a specific, though perhaps not immediately obvious, reason for a particular situation or action. For example, “For a particular cause, the meeting was postponed.” It gives a more deliberate and considered tone compared to “for some reason”.
Another formal alternative is “due to a specific consideration”. This expression emphasizes that there is a particular factor or consideration that has led to a certain outcome. For instance, “Due to a specific consideration, the decision was made to change the project plan.” It sounds more professional and thought-out.
“on account of a certain factor” is also a formal synonym. It indicates that there is a definite factor that is responsible for a particular state of affairs. For example, “On account of a certain factor, the event had to be rescheduled.” This phrase is more formal and can be used in business or academic writing.
“by virtue of a particular circumstance” is a more elaborate formal synonym. It suggests that a particular circumstance has given rise to a specific result. For example, “By virtue of a particular circumstance, the company was able to secure a large contract.” It has a more sophisticated and refined tone.