Is this sentence correct:
"If this was true fifty years ago, it must be all the more so in modern times"
Did I use the expression "all the more so" correctly in this sentence?
Thanks
This is acceptable usage.
In this case "so" is standing in for "true".
You are in effect saying "it must be truer now than it was 50 years ago".
Of course, the reader would probably expect a reason! Consider also whether it's semantically correct for the argument you're making to say something is somewhat true at one point and more true at another point.