The Penguin Dictionary of American English Usage and Style : A ...

68 comparative and superlative degrees
Comparative and superlative degrees.
Many an adjective or adverb has
three forms, or degrees (that is, degrees
of comparison): the positive, comparative,
and superlative.
1. A word in the positive degree describes
something—say, as soft, high,
fast, sweet, or good—without comparing
it with something else.
2. The comparative degree indicates that
something exceeds something else. It
is softer, higher, faster, sweeter, or better.
3. The superlative degree is the most extreme:
softest, highest, fastest, sweetest,
or best. Something is in the top
order or surpasses all others in some
respect.
Use the superlative only when what
you describe is among three or more of
its kind. If it is one of only two, use the
comparative. “This melon is the largest
of the three” but “This melon is the
larger of the two.”
It is a common mistake to use the superlative
instead of the comparative; for
instance, to say that someone is the
“tallest” of two. See BETTER and BEST
(etc.). A talk show host made the opposite
mistake: “The three networks were
fighting to see who would get the bigger
piece of the pie.” One network would
get the biggest piece. (And “who”
should be which. See WHO, THAT, and
WHICH, 1.)
A book about business mistakes
makes a verbal mistake:
The firm encountered legal problems
in West Germany, however, because
German law dictates that superlatives
are not permitted. One product cannot
be called better (or stronger) than
another.
Better or stronger are not “superlatives.”
They are comparatives.
See also COMPARED TO and COM-
PARED WITH; Comparison; MORE
and MOST; MORE with comparative;
MOST with superlative; Numbers, 10B,
D.
COMPARED TO and COM-
PARED WITH. 1. Similarities and
contrasts. 2. Two other problems.
1. Similarities and contrasts
Each of these four sentences contains
one wrong word:
. . . Detective Tom Lange . . . asked
him to bring the glove found outside
Simpson’s mansion into the middle of
the crime scene so it could be compared
to the glove found near the bodies.
Typically, community college parttimers
earn about half the hourly pay
of full-time teachers—$28.38 compared
to $53.36. . . .
There were not many words in the
first ROGET’S THESAURUS, compared
to the number in a volume like
this. . . .
There are no published studies that
compared the drug to placebo or fake
pills.
Each “to” should be with.
When we compare something to
something else, we are likening the two
things or pointing out similarities. (“The
streaks on Mars used to be compared to
our canals.” / “People have compared
Castro to Stalin.”)
When we compare something with
something else, we are either contrasting
the two (“$28.38 compared with
$53.36”) or examining them to look for
differences or similarities (“studies that
compared the drug with placebo or fake
pills”).
Is all that just unnecessary fussiness?
The use of “to” instead of with by a