Substitution: do so, the former, the latter

Do so, the former and the latter, that of and those of, such, thereof: avoiding repetition in formal writing.

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Substitution means using a short word or phrase in place of words that have already been said. In conversation, English uses one, do and so for this. Formal writing has its own set: do so for a verb phrase, the former and the latter for one of two things, that of and those of in comparisons, and such for something of the kind just mentioned.

Instead of repeating	Formal substitute	Example
a verb and what follows it	do so	Staff may leave early if they wish to do so.
the first or second of two	the former, the latter	Leeds and Bristol were considered; the latter was chosen.
a noun in a comparison	that of, those of	The climate of Spain is warmer than that of Britain.
something of the kind mentioned	such	Such a decision needs careful thought.
a whole clause	so, not	Is the offer still open? If so, I'd like to accept it.

Do so for a verb phrase

Do so (does so, did so, doing so, done so) replaces a verb with its object or other words after it. It is used for actions, not usually for states, and is more formal than do it or do that.

The minister was asked to resign, but refused to do so.
Anyone wishing to apply should do so before 30 June.
Prices rose sharply in 2022 and have continued to do so.
The company raised its prices. In doing so, it lost a third of its customers.
By doing that.
Incorrect: She knows the answer, and her brother does so too.
Correct: She knows the answer, and so does her brother. / ... and her brother does too.
Know is a state verb, so do so is not possible.

The former and the latter

The former refers to the first of two things or people just mentioned, the latter to the second. They are used when exactly two have been named. For three or more, the first and the last are clearer.

The company considered moving to Leeds or Bristol and finally chose the latter.
Bristol.
Both Anna and Tom applied; the former got the job.
Of the two plans, the former is cheaper but the latter is more flexible.
The report looked at France, Italy and Spain. The last of these has the highest unemployment.
With three countries, the last of these is clearer than the latter.

Both can be followed by a plural verb when they refer to a plural noun: We spoke to teachers and parents. The latter were more critical.

That of and those of

In a comparison, that of replaces a singular noun and those of a plural one, so that like is compared with like. Formal writing prefers this to repeating the noun.

The population of London is larger than that of Paris.
Our prices are lower than those of our competitors.
Incorrect: The prices in London are higher than that in Manchester.
Correct: The prices in London are higher than those in Manchester.
Prices is plural, so use those.

In everyday English, a possessive is common too: Our prices are lower than our competitors'. In formal writing, compare like with like: the climate of Spain with that of Britain, rather than with Britain itself.

Such and as such

Such + noun refers back to something of the kind just described. With a singular countable noun, use such a / an. As such means "in that role" or "in the exact sense of the word".

The council plans to close two libraries. Such a decision would hurt the whole town.
We received over 200 complaints. Such numbers are unusual.
He is the manager, and as such he is responsible for safety.
Because he is the manager.
There is no menu as such, just a list of the day's dishes.
Not a real menu.

As such is also widely used to mean "therefore". Some careful writers avoid that use, so in formal writing therefore or for this reason is the safer choice.

So and not for a clause

So and not replace a whole clause after if and after verbs such as think, hope, believe, appear. The same replaces something already stated.

Check whether the form has been signed. If so, send it to the office; if not, return it.
Will the delay affect the budget? It appears so.
Prices rose in May, and the same happened in June.
The new rules apply to staff, and the same is true of visitors.

Thereof, therein and the like

Thereof (of it), therein (in it), hereby (by this) and herewith (with this) appear in legal and very formal texts. Learners should recognise them, but they sound old-fashioned in ordinary writing.