Arthur said:
Commas generally indicate pauses in speech.
If, as here, the sentence would make no sense without the pauses,
then the commas are required.
Nonsense!
Unless the sentence is meant to be read aloud, the pause makes no sense.
The purpose of the comma (in your example and mine)
is to set off a prepositional phrase that appears out of place.
If you had written, "The commas are required
if the sentence would make no sense without the pauses" or
if I had written, "The pause makes no sense
unless the sentence is meant to be read aloud"
the comma would not be required.
However (and here the comma is again required),
According to The American Heritage Dictionary of the English Language
http://www.bartleby.com/61/58/H0305800.html
USAGE NOTE: Although some grammarians have insisted that however should
not be used to begin a sentence, this rule has been ignored by a number
of reputable writers. Forty-two percent of Usage Panelists say they do
not follow the rule in their own writing, 19 percent say they observe it
only sometimes, and 36 percent say they usually observe it. See Usage
Notes at but, whatever.
there are situations such as this one here
which do not generally require paired commas.
Admittedly, inserting paired commas tends to make things easier to read,
especially in contrived sentences such as the ones above ---
but the points are that commas are not *always* required,
The comma before a conjunction (i.e. , and)
is redundant and superfluous.
and that random English-usage discussions are *always* off-topic here.
But no [white]space should ever appear before a comma
and at least one [white]space should appear after a comma.
s