NATURE AND VARIABILITY OF COMPARISON
To compare is to point out similarities and/or differences. It is an important part of academic and professional writing (see, for example, 94. Essay Instruction Words and 115. Describing Numerical Data). Reflecting this importance, the grammar and vocabulary of comparison are quite varied (see 149. Saying How Things are Similar).
Unfortunately, the variety of ways to compare means that numerous kinds of language error can be made by writers who are not used to English. Some of these are considered elsewhere within this blog, but the aim of the present post is to survey in a more complete way all of the aspects of comparison-making that seem to cause errors of grammar and vocabulary.
COMPARISON ERRORS ALSO CONSIDERED ELSEWHERE
One aspect of comparison-making that is not an error but can cause confusion is the use of more adjectives before an uncountable or plural noun. The multi-use nature of more means that there can be uncertainty about whether it goes with the adjective or the noun (see 182. Structures with a Double Meaning 2, #3).
The following actual errors in comparison-making are considered in depth elsewhere within this blog.
1. “On the Contrary”
The correct use of this phrase is examined in depth in the post 20. Problem Connectors. Being a “connector”, on the contrary needs to go in the second of two closely-related sentences to help show the link between them (see 18. Relations Between Sentences and 40. Conjunctions versus Connectors). The error is to think that on the contrary shows the meaning of “difference” or “contrast”. The connectors that need to be used instead for this meaning are in contrast, by contrast or on the other hand. The correct use of on the contrary is to clarify a preceding negative statement, e.g.:
(a) Paris is not at all far from London. On the contrary, it can now be reached by train in a little over two hours
Connectors that help to show a similarity are similarly, likewise, in a similar way and in the same way.
2. “Like” and “Unlike”
This is the focus of the post 56. Comparing with “Like” and “Unlike”. The error that can occur is to use (un)like and its following noun to make a central point. The central point must instead be outside these words. Consider this:
(b) Ants form colonies headed by a queen, like bees.
This is a sentence about ants, not ants and bees. If the message is supposed to be as much about bees as ants, then a more appropriate wording might be and so do bees in place of like bees, or, more formally, Both ants and bees … at the start (see 149. Saying How Things are Similar). The difference-showing equivalent of these (for avoiding unlike) is whereas.
Very often, information that is not the focus of a sentence is assumed to be already familiar to the reader or listener. It is certainly possible to understand (b) to mean “You know how bees form colonies headed by a queen; well, ants do the same”.
3. “The One(s)” versus “That/Those”
This is one of the points in the post 63. Constraints on Using “the one(s)”. Quite often there is a free choice between the one(s) and that/those, but in formal comparison-writing it is normal to use only that/those, like this:
(c) Deaths from road accidents are now much higher than those from malaria.
Using that/those is often necessary to ensure that a comparison is logically correct (see “Comparing Like with Like” in 170. Logical Errors in Written English).
4. “Aspects” versus “Respects”
These two words are discussed in the post 81. Tricky Word Contrasts (2). They mean more or less the same thing (“parts”), but only one is commonly found in comparison sentences: respects. An example of its use is:
(d) Medicine and Veterinary Science differ/are similar in a number of respects.
In sentences like this, respects means more or less the same as ways. Very commonly, it follows the preposition in, and the sentence will contain a verb of similarity or difference (e.g. DIFFER, CONTRAST WITH, RESEMBLE, BE LIKE). It is always wrong to use aspects.
FURTHER ERRORS IN MAKING COMPARISONS
The following further aspects of comparisons can cause errors.
1. The Need for a Comparative with “than”
English sentences with than usually need a comparative word in them – one with -er, more, less etc. (though American English also allows the non-comparative word different). Some other languages, by contrast, show comparisons only with a word like than – they do not require a comparative form with it. Speakers of such languages can easily forget to put an English adverb or adjective before than into the comparative form, producing such errors as *clear than or *quickly than.
2. Preposition Use
Some words indicating a similarity or difference are followed by a typical preposition that can be hard to remember (for the concept of “typical” prepositions, see 111. Words with a Typical Preposition). The underlined words in the following sentences are of this kind. What should the preposition be in each blank space?
(e) Greek cuisine is similar … Lebanese.
(f) Zambia has almost the same climate … Zimbabwe.
(g) Ford’s new model looks virtually identical … the old one.
(h) Winter in Russia is very different … summer.
The correct prepositions are to, as (not strictly a preposition but used similarly), to and from (than in American English). These are nearly always the only possible choices, except that some contexts require the same to have that rather than as (see 87. “Same As” versus “Same That”). Using of with any of the words is hardly ever correct.
One other point to note is that no preposition is used after the verb RESEMBLE. This verb is similar to those discussed in the post 42. Unnecessary Prepositions.
3. Clarification of a Similarity or Difference
The simplest kind of comparison merely indicates the existence of a similarity or difference. This is the case, for example, in sentence (e) above. However, sentences like this can generally be expanded so as to say what the similarity or difference is. One way of doing this is with in. Thus, a continuation of (e) might be … in its use of olives and feta cheese.
Even if the expansion needs a verb, you should still use in (not because). You can either put -ing on the end of the verb to make a gerund, e.g. in using (see 70. Gerunds), or add that after in, like this:
(h) Greek cuisine is similar to Lebanese in that it involves large quantities of olives and feta cheese.
This use of in that is a rare example of that being necessary after a preposition instead of the fact that (see 153. Conjunction Uses of “that”).
4. Use of “Less” & “Fewer” before Nouns
Comparative adjectives like better, more difficult and less interesting are an important means of expressing differences. In addition, more and less are common by themselves (as pronouns) or with a following noun like this:
(i) Jazz has less popularity today than in the past.
Here, the noun popularity is uncountable. If a countable noun is used instead, it has to be plural, and was traditionally felt to need fewer instead of less (… has fewer fans). I say “traditionally” because many younger English speakers today would use less in both cases.
5. Use of “the” with Superlative Adjectives
It is quite a common error for the to be left out before a superlative adjective or adverb. However, a blanket call to always use the before superlatives is also incorrect. One rule, usually mentioned by grammar books, is that most + ADJECTIVE has no the when it means very (see 98. “Very”, “Much” & “Very Much”), like this:
(j) Physicists found the behaviour of sub-atomic particles most perplexing.
However, even ordinary superlatives, with and without most, sometimes lack the:
(k) The police are busiest in the summer.
I think the reason for not using the here is that a special kind of comparison is being made: the police are being compared with themselves rather than with other people. The sentence means the police are busier in summer than they are in other seasons. If the was added to (k), on the other hand, the comparison would be between the police and other people. The sentence would say that the police are busier than other people in the summer. For a further point about superlatives, see 102. Adjectives with No Noun 2: Thing-Naming.