149. Saying How Things are Similar

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There are numerous ways to say how things are similar, though they are not always interchangeable

THE VARIABILITY OF SIMILARITY-NAMING

Discovering and naming similarities is a major way of thinking analytically, especially during classification (see 162. Ways of Writing about Categories). As a result, similarities feature quite heavily in both academic and professional writing (see 94. Essay Instruction Words and 115. Surveying Numerical Data).

English has numerous ways of indicating a similarity. Some just say that a similarity exists:

(a) Greek cuisine is similar to Lebanese.

More often, however, there is a need to also say what the similarity is – for example that the two cuisines in (a) both use olive oil and white cheese. Once again there are various ways of doing so.

Another cause of linguistic variety is whether or not the writer expects the reader to be familiar with one of the two similar ideas. This is not surprising, since familiarity expectations quite regularly affect language choice in English (see 156. Mentioning What the Reader Knows Already). Consider the following similarity statement:

(b) Coal stations pollute, like motor vehicles.

The underlined words here indicate that the reader already knows about motor vehicle pollution, so that the sentence is primarily asserting the polluting nature of coal stations, motor vehicles being mentioned only to make this main message clearer. On the other hand, if the two similar ideas are both expected to be unfamiliar to the reader, the language chosen to express them might look like this:

(c) Coal stations pollute, and so do motor vehicles.

Even more variability of similarity-naming comes from the fact that it can be done in not just a single sentence in ways like those above, but also in multiple sentences, just as is the case in other key writing functions like example-giving, expressing consequences, listing, specifying and naming exceptions.

This post surveys the main ways of expressing a similarity in English. For a similar survey of difference language, see 216. Indicating Differences.

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NAMING A SIMILARITY IN A SINGLE SENTENCE

1. Similarities to a Familiar Idea

The word(s) indicating this kind of similarity in a single sentence may be a verb, adjective, preposition or conjunction. Common verbs are RESEMBLE and MIRROR:

(d) Coal stations resemble motor vehicles in polluting.

One could also say can be likened to. Note the use of in before the similarity (polluting). It is usually followed by either a verb in the gerund (-ing) form, as here, or that and a subject and ordinary verb (…in that they pollute – see 153. Conjunction Uses of “that”). In informal contexts one might see because instead of that (see 82. Common Errors in Making Comparisons, #7).

Adjectives indicating a similarity to a familiar idea can be made by adding -like to the familiar idea (provided it is just a single word), e.g. truck-like (see 106. Word-Like Suffixes and 163. Ways of Naming Properties). Other adjectives are synonyms of the preposition like (see similar etc. below).

The main preposition for comparing something with a familiar idea is like (see 56. Comparing with “Like” and “Unlike”), used either alone or after a “degree” adverb (a little, exactly, just, much, quite, somewhat, very). The familiar idea will be the noun after like. Surrounding commas may be necessary, depending on meaning. Consider (b) again:

(b) Coal stations pollute, like motor vehicles.

This says what coal stations do, and likens it to the familiar behaviour of motor vehicles. Without the comma, however, the focus would shift from what coal stations do to how they do it: their way of polluting resembles that of motor vehicles (see 53. “As”, “Like” and “Such As”). Grammatically, like then relates just to the verb before it (pollute), not everything before.

In (b), with or without commas, the like phrase is adverb-like. This allows like to be paraphrased by comparably to, similarly to and in the same way as. Elsewhere, however, like phrases may be adjective-like, describing a previous noun:

(e) The illness caused by the new virus was like influenza.

The noun being described here (illness) is separated from like by was. This use of like has such synonyms as akin to, analogous to, comparable to and similar to. All can be weakened with approximately, fairly, quite or roughly. The same as is also a synonym if used after almost, approximately or roughly (it cannot follow fairly or quite: see 231. Confusions of Similar Structures 3, #2). For further aspects of the same, see 87. “Same As” versus “Same That”.

Another preposition that can help show a similarity to something familiar is the second as in as… as… statements:

(f) Cheetahs run as fast as cars on a freeway.

The first as here is an adverb quantifying fast (see 194. Adverbs that Say How Much). The second as introduces the noun cars, implying it to be familiar to the reader. Thus, (f) is about the speed of cheetahs, and uses the speed of cars on freeways to make it clear. Comparisons using as… as… are typically needed when the similarity – fast in (f) – is expressed with either an adverb or an adjective. For more on the adjective use, see 159. Exotic Grammar Structures 2, #5.

One other way of showing how a new idea resembles a familiar one in the same sentence is by placing the latter after a conjunction. This is only possible if the familiar idea contains a verb, since conjunctions usually need one. Here is an example containing the conjunction just as:

(g) Just as water travels to the lowest possible level, so heat transfers to cooler substances.

In this case, just as introduces the first of the two verbs in its sentence and, with so before the other one, is part of a “double” conjunction (see 64. Double Conjunctions). Just as can also go between the two verbs, but then has no partner so.

The verb after just as in (g) (travels) is different from the other one in the sentence (transfers). This is a common use of just as, though as alone is often possible too. Just as can also be used when the two verbs are the same:

(h) Aeroplanes are fuelled by kerosene just as oil lamps are.

As this shows, the main verb (are fuelled) when repeated after as is abbreviated. Repetition of multi-word verbs is done by means of their first word alone (are above), while single-word ones become DO (without so: see 212. Special Uses of “Do” 1), unless they are BE, which is itself repeated.

If a sentence like (h) has as or (informally) like instead of just as, there is sometimes a comma in front, depending on meaning, as with the prepositional use of like in (b).

One other similarity-showing conjunction, as if (+ past tense), indicates an exact resemblance (see 191. Exotic Grammar Structures 3, #3).

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2. Similarities to an Unfamiliar Idea

In sentence (c) above, the words and so do imply that pollution by motor vehicles is new information. The verb do is an abbreviated repetition of the previous verb, determined in the same way as repetitions in sentences like (h). After and, various other expressions are also possible instead of the slightly informal so do…, including …act(s) similarly and …do(es) the same.

Similarities of this kind involving negative verbs need neither instead of so:

(i) Helium does not easily form compounds and neither does argon.

One alternative to and so is as. To distinguish it from the earlier-mentioned use introducing a familiar idea, the following noun and abbreviated verb have to be mentioned in reverse order, like in direct questions: as do motor vehicles (see 159. Exotic Grammar Structures 2, #1).

Another formal possibility with two unfamiliar ideas is both. It may refer back to them as a pronoun or adjective-like “determiner” (see 271. Tricky Grammar Contrasts 3, #2), or forward as a conjunction partnering and (see 64 Double Conjunctions):

(j) Both coal stations and motor vehicles pollute.

Neither… nor… likewise indicates a similarity between two unfamiliar negatives.

Two unfamiliar ideas can also go without both before a similarity verb like …resemble each other, are similar, are (almost) the same or are alike. The nature of the similarity is usually specified with in:

(k) Coal stations and motor vehicles resemble each other in causing pollution.

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SIMILARITY-NAMING IN MULTIPLE SENTENCES

There are two main ways of indicating a similarity with two or more sentences. In one, two ideas are named and said to be similar in the first sentence, and the nature of the similarity is identified afterwards:

(l) COAL STATIONS resemble MOTOR VEHICLES. They (both) produce harmful gases.

The first sentence here allows the usual alternatives to resemble – mirror, act like, are like and are akin (or comparable or similar) to. An alternative is to begin There is a similarity (or a resemblance) between… (see 161. Special Uses of “There” Sentences, #2). One advantage of this is that the similarity can be characterised with an adjective like major or interesting.

If a list of similarities is to be given, the first sentence can show this by ending in…ways, the dots representing an exact or vague number word (see 122. Signpost words in Multi-Sentence Listing and 96. Avoiding Untruths 2). An alternative to ways is respects (but not aspects – see 81. Tricky Word Contrasts 2, #4).

The second sentence should not normally have any special wording to show how it is linked to the first (see 117. Restating Generalizations More Precisely). Its subject may be they both, suggesting the behaviour of both similar ideas is new to the reader, or just it/they, referring just to the first-mentioned idea and suggesting only its behaviour is new.

The other main type of multi-sentence similarity-describing names one of the two similar ideas in the first sentence and the other in the second. There are various ways of doing it:

(m) MOTOR VEHICLES produce harmful gases. They thus resemble COAL STATIONS. (SAME BEHAVIOURS/FAMILIAR SECOND POINT)

(n) MOTOR VEHICLES produce harmful gases. COAL STATIONS are similar/do the same. (SAME BEHAVIOURS/UNFAMILIAR SECOND POINT)

(o) HEAT transfers to cooler substances. It resembles WATER travelling to the lowest possible level. (DIFFERENT BEHAVIOURS/FAMILIAR SECOND POINT)

(p) BIRDS are optimised for flight. Similarly, AIRCRAFT are designed with flying in mind. (DIFFERENT BEHAVIOURS/UNFAMILIAR SECOND POINT)

“Same behaviours” here means that the behaviour named in the first sentence – produce harmful gases in (m) and (n) – is also implied in the second sentence (coal stations do it too).

It is noticeable here that familiar second points begin with a pronoun matching the main noun of the first sentence – they in (m) repeats motor vehicles; it in (o) repeats heat. Also noticeable is the fact that only (m) allows a consequence connector (thus, therefore, hence, consequently), presumably because of the specific features involved (same behaviours/ familiar second point).

In contrast, the connector similarly (or synonyms such as likewise and in the same way) seems possible only in combinations like (p) (different verbs/ unfamiliar second point). Note that in a similar vein (see the end of 241. Some Common Figurative Phrases) has a different (topic-introducing) use.

148. Infinitive Verbs without “to”

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There are quite a lot of situations that make it possible or necessary to write an infinitive verb without “to”

THE POSSIBILITY OF DROPPING “to” FROM ENGLISH INFINITIVES

English language courses usually make it clear quite early on that “infinitive” verbs (those that lack an ending after to) are sometimes used without the to. A well-known occasion, for example, is after “modal” verbs like will, can, should and must. However, detailed surveys of all the situations where so-called “bare” infinitives are possible or necessary are much harder to find. It is this kind of survey that I am attempting in the present post, in the hope of resolving every possible uncertainty that readers might have about the use of bare infinitives. I will consider first situations where dropping to is optional, and then those where it is compulsory.

A preliminary point to note is that the to of infinitive verbs is not a preposition (see 3. Multi-Use Words and 35. Words Followed by “to -ing”). It normally helps to distinguish infinitives from other verbs without an ending, such as imperatives (see 128. Imperative Verbs in Formal Writing), subjunctives (see 118. Problems with Conditional “if”, #6), and plurals in the present simple tense (see 12. Singular & Plural Verb Choices).

Guinlist posts that give some attention to the use of ordinary to infinitives include 60. Purpose Sentences with “For”,  78. Infinitive versus Preposition after Nouns,  83. Adjectives before a “to” Verb,  105. Questions with a “to” Verb,  119. BE Before a “to” Verb,  183. Statements between Commas,  208. Verbs with an Object + Infinitive and 239. Noun Phrases Made with a “to” Verb.

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OPTIONAL BARE INFINITIVES

The to of an infinitive verb is most commonly optional when the infinitive is the second of a pair that are combined together by a suitable linking word. In most cases the linking word will be a conjunction, especially and:

(a) To paraphrase well, one has to comprehend and (TO) REMEMBER the source text.

The optionality of to before remember here is not surprising, given the way and generally in English allows repeated words to be dropped (see 36. Words Left out to Avoid Repetition and 174. Eight Things to Know about Conjunctions, #6). The conjunction than is another common one found with a dropped to:

(b) Children are often keener to play with their parents than (to) watch TV.

Note, though, that when than is combined with rather, keeping to is rare (see #3 below).

Situations where the to of an infinitive is optional but not linked to one used earlier are quite rare, but do exist. One kind begins with what or all (that):

(c) What / All (that) plants DO at night IS (to) absorb carbon dioxide.

This is a sentence type considered in depth in these pages in 145. Highlighting with “What” Sentences. It contains two verbs, DO and BE, the latter followed by an infinitive clarifying what DO means. The effect is to mark the infinitive verb’s meaning as the main information in the sentence. It is the to of such infinitives that is usually optional.

One other place where a bare infinitive is optional but not linked to an earlier infinitive with to is after the verb HELP and its object, like this:

(d) Nicotine chewing gum can help smokers (to) quit.

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COMPULSORY BARE INFINITIVES

There seem to be at least five situations where a bare infinitive must be used.

1. After Modal Verbs and DO

This familiar kind of bare infinitive is illustrated in such combinations as will know, can go, may be, must have and should say, where the first word is always a verb of the “modal” kind. The same need also exists after the non-modal auxiliary verb DO (e.g. does not think).

A small potential for confusion is with the “semi-modals” NEED and DARE, which in questions and negative statements allow a choice between use like ordinary verbs (with DO and to) and use like “modal” verbs (without them). Compare the following:

Use like Ordinary Verbs (with to)

Negative Statement: … DO(ES) not need/dare TO SAY

Question: DO(ES) … need/dare TO SAY?

Modal Use (without to)

Negative Statement: … need not/dare not SAY

Question: need/dare … SAY?

For more information about NEED within these pages, see 83. Adjectives before a “to” Verb (last section), 129. Differences between Necessity Verbs and 208. Verbs with an Object + Infinitive.

Although there is a choice between the modal and non-modal uses of DARE and NEED in negative statements and questions, the dropping of to in the modal use is still in a sense “compulsory”. This is because once a decision has been made to use NEED or DARE as a modal – for example by placing not after it instead of before in a negative statement, or a subject noun after it instead of before in a question – then there is no choice about dropping to from the following verb.

Sometimes the need for to to be dropped because of a modal verb even affects what sentences like (c) above, where there would normally be a choice regarding to. This happens when the DO after what includes a “modal” verb, e.g. can do or will do. In such cases the modal verb’s requirement for an absent to will affect not just DO but also the later infinitive, so that the choice there will disappear (… is absorb carbon dioxide).

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2. After the Object of Certain Verbs

Many “cause” verbs can be followed by an object that is also the subject of an infinitive verb placed immediately after it (see 208. Verbs with an Object + Infinitive, #7). An example is:

(e) Price increases usually CAUSE demand TO FALL.

Most verbs like cause in this example (ALLOW, ASSIST, ENABLE, LEAD etc.) require the following infinitive to have to. However, there are at least three exceptions: MAKE (= “cause by forcing”), LET (= “cause by allowing”) and HAVE (= “cause by organizing”).

Either MAKE or LET can replace cause in (e), but will need to fall to drop its to (see 10. Words with Unexpected Grammar 1, example (a), and 141. Ways of Using MAKE, #3). The use of causative HAVE is illustrated by the following sentence from 116. Rarer Uses of HAVE:

(f) It is desirable to have young children work in groups.

In addition to these three cause verbs, there are a few “perception” ones with a similar but not identical requirement:

(g) On SEEING the liquid CHANGE colour, turn off the heat.

Change is here a bare infinitive after the object of the perception verb seeing. Other perception verbs are FEEL, HEAR, LISTEN TO, NOTICE, OBSERVE, SENSE, SMELL and WATCH.

The infinitive is not the only verb form that can follow the object of a perception verb, but it is compulsory for expressing the particular meaning of a completed rather than ongoing action. The alternative form, for ongoing actions, is an -ing participle (see 231. Verbs with an object + “-ing”). Having -ing for a completed action instead of a bare infinitive would be a grammar error of the “invisible” kind (see 100. What is a Grammar Error?).

The verb HAVE with a later bare infinitive can mean not just “cause”, as indicated above, but also “suffer”, like this:

(h) Farmers can easily have pests eat(ing) their crops.

HAVE with this passive meaning resembles perception verbs, and like them it allows a choice between a following infinitive and -ing verb. In fact, even HAVE with the “cause” meaning allows the same choice: working is possible in (f) as well as work.

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3. After “Sooner than” and “Rather than”

Sooner than can be used as a preference-expressing conjunction:

(i) Many cyclists wear a silly-looking helmet sooner than RISK serious injury.

As with all conjunctions, a following verb is typical. However, this verb must always be a bare infinitive. Rather than is similar, except that it allows an -ing verb as an alternative to the infinitive (e.g. rather than risking above). The meaning of rather than is also wider: sometimes it is little more than that of the preposition instead of.

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4. After DO + “all”/”nothing” + except…

An example of this use is:

(j) The program does everything except monitor performance.

The main verb in such sentences must always be DO and must be accompanied by an expression (everything above) that means “all” or “none” (see 215. Naming Exceptions). It is the verb after this use of except (here monitor) that is usually a bare infinitive. An -ing form is an alternative when the main verb is in a continuous tense (is doing … except monitoring above).

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5. In Infinitival “Why” Questions

Questions using an infinitive verb are the focus of the Guinlist post 105. Questions with a “to” Verb. They are often just the question word and the verb, as in what to do(?), where to go(?) and whether to respond. Usually the infinitive verb needs to, but to must be dropped when the question word is why, as in why wait? and suggestions with why not…? (see 274. Questions with a Hidden Meaning, #3).