"I can do it too"

Question

Can you say

I can do it too

meaning that I can also do what someone else just did?

I had an argument with my mate who is a native speaker (or that's what she claims). I was pretty sure you can say it like that but she said you can't.

Answer 1

There is nothing grammatically wrong with "I can do it too." Without a context, of course, one can't know what the "it" refers to, but as long as the listener knows the reference there is no problem. It is also correct to say "I can do that too" and "I can do this too."

"I know you can change the bicycle tire, but can you change the chain?" "Yes, I can do that too."

Suppose that your friend David is juggling six balls and someone says "David is juggling 6 balls." Since the context is clear it would be correct to say, "I can do it too." Then you do it and decide to add yet another ball as you say "I can do this too."

Answer 2

I can do it too.

is understandable and is used to signify that the speaker can also perform an action. It gets used by younger children and people making a point that something is no big deal.

Often instead, one might say

I can do that too.
I can do that also.

since whatever is being discussed is usually away from the speaker.

Answer 3

It depends on the context, but in most cases, no, that sentence is not going to be idiomatic.

The problem is the pronoun "it." "It" is used only in cases where there is a clear grammatical antecedent. For example:

You silently watch someone juggle three chainsaws. You would say:

I can do that, too.

You could not use "it" in this sentence, because there is no grammatical antecedent. Think of it this way: the word "that" is referring the listener out into the real world; the word "it" is only referring to something earlier in the sentence. In grammatical terms, "that" is a demonstrative pronoun, and "it" is a personal pronoun.

Even if you were responding to another person's sentence, it would be more idiomatic to say "that" instead of "it." For example:

I can juggle chainsaws, you know.

Yeah, I can do that too.

The only time you would be likely to use "it" in this context is where it is acting as a replacement for a noun or noun phrase:

Juggling chainsaws is hard, but I can do it.

Is juggling chainsaws hard? Yes, but I can do it.

Is it hard to juggle chainsaws? Yes, but I'll bet I could do it if I tried.

If you use the sentence as you suggested:

I can do it.

without any obvious context, people will either be confused, or they will think you mean one of two things:

1) You can achieve your goals; or

2) You can have sex.

These are the two default definitions of "it" where it is used without an antecedent.

Answer 4

I can do it too. is ok, but it really should have a comma: I can do it, too.