William Strunk writes in the 1914 edition of his Elements of Style:
Place a comma before and or but introducing an independent clause.
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Two-part sentences of which the second member is introduced by as (in the sense of because), for, or, nor, and while (in the sense of and at the same time) likewise require a comma before the conjunction.
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Do not join independent clauses by a comma.
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If a conjunction is inserted, the proper mark is a comma (Rule 4).
Now more than a hundred years later, a grammar stylistic rule commonly taught by today’s writing-style guides categorically states that whenever the word so connects two independent sentences, a comma should be placed before that so. But in this example, so apparently connects two independent clauses, but no comma is placed.
Fees for higher education are expensive and not affordable for everyone so according to some university should be free for all people, regardless of their background.
Why was that written without a comma before the so? Shouldn’t it have been written at least like this:
Fees for higher education are expensive and not affordable for everyone, so according to some university should be free for all people, regardless of their background.
Or like this:
Fees for higher education are expensive and not affordable for everyone, so according to some, university should be free for all people, regardless of their background.
Or even like this:
Fees for higher education are expensive and not affordable for everyone, so, according to some, university should be free for all people, regardless of their background.
Why did the original leave out that critical comma? Is this not required? Any explanation on this strange lapse compared with what I thought the proper rule always had to be would be very much appreciated.