First is an adjective and “firstly” is an adverb (and the same can be said for “secondly”, etc.).
Adverbs say something about a verb. Here is an example: Mr. Rajoy quickly ran into the bar.
That is easy. What about these sentences?
- Firstly, Mr. Rajoy drank a beer.
- Secondly, he drank a glass of red wine.
Where are the verbs that are attached to the adverbs (for example, firstly)? There are none. An error. The correct form should be:
- First, Mr. Rajoy drank a beer. Second, he drank a glass of wine.
Words such as “first” are adjectives, in this case adjectives with elliptical (elíptico) nouns. The text could read: Mr. Rajoy´s first action was that he drank a beer. Here we have a sentence of ten words, compared to six words (First, Mr. Rajoy drank a beer).
On the basis that six words are better than ten words, we know which option to choose.
How often have you seen such a sentence in a report, review or speech (discurso)?
“Firstly (en primer lugar, primero), I want to deal with the issue of taxation… Secondly (en segundo lugar), I would like to… ”
The use of “firstly” and “secondly” here is simply incorrect. “Firstly” is an adverb and adverbs say something about verbs. Are these words telling us something about how something was done? No. Adverbs also give more information about adjectives such as in this example:
- “Mr. Morales was severely (seriamente) critical of the Spanish government´s high tax policy”.
Here is a simple example of an adverb telling us something about an action.
- “The president of the Canarian government drank the wine quickly”, or “He quickly drank the wine”.
The adverbs give us more information about how the person drank the wine.
Another example would be:
- “Mr. Cameron, the British Prime Minister, slowly drank the Spanish beer and was highly critical of its quality”.
- “Highly” is an adverb which gives more information about the adjective “critical”: “Slowly” tells us how he drank the beer.
So, in the sentence, “Firstly, I want to deal with the issue of taxation (tributación)”, where is the adverb? It is absent (es ausente). Does it tell us how I dealt with the issue of taxation? No.
The correct form would be to say “First, I want to deal with the issue of taxation.” Second, I would like… The word “first” in this context is an adjective used elliptically (de manera elíptica).
