[Idiom] so too does

[yuriya]

Hi, everyone! I've been told that "so" means "too" in the following:
1) I like him. So do I. (=Me too)
2) I like him and so does she.

I've noticed, however, that "too" sometimes follows "so" as in the following:
3) As systems increase in size, so too does the bureaucracy.
4) While your speed increases, so too does your mass.

I feel that "too" can't be dropped in sentence 3) and sentence 4) but wonder what makes the difference? It seems to me, though, that transitive/intransitive thing has something to do with it (like him vs increase), but I'm not sure. What say you? Thanks in advance!
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[2006]

Hi, everyone! I've been told that "so" means "too" in the following:
1) I like him. So do I. (=Me too)
2) I like him and so does she.

I've noticed, however, that "too" sometimes follows "so" as in the following:
3) As systems increase in size, so too does the bureaucracy.
4) As your speed increases, so too does your mass. "As" is much better than "While".

I feel that "too" can't be dropped in sentence 3) and sentence 4) but wonder what makes the difference? "too" can be dropped and usually is.
It seems to me, though, that transitive/intransitive thing has something to do with it (like him vs increase), but I'm not sure. What say you? Thanks in advance!
__________________
Feel free to correct my sentences. I welcome them, not resent them!

2006

 

[SoothingDave]

The "too" can be dropped in 3 and 4. It's there for emphasis.

 

[yuriya]

Thanks for your insight. If it is a matter of style or emphasis, is it also possible to add "too" in sentence 1) and 2)? I've never come across so too before a pronoun. Is the pronoun a factor there?
1) I like him. So too do I. (?)
2) I like him and so too does she. (?)

 

[SoothingDave]

Adding "too" to sentences 1 or 2 would not be natural. I'm not sure quite why, but something about the formulation in 3 & 4 (as this... so too that) lends itself to the "too" that doesn't work in other formulations.