as well
 

Do you agree with me?

-John's impulse to do this did not stop as well.(=Someone else's stopped, but John's did not)

-John's impulse to do this did not stop either.(=Someone else's did not stop, neither did John's)

I think 'as well' is possible with 'not', but the meaning is entirely different from 'either'; do you agree?

Re: as well
 

No. The second sentence is fine but the first is not possible. "As well" means "too" - it's a connective of addition, meaning that the two propositions are the same in some way. Again, you've eliminated the context - and it is the context which would disambiguate the meaning. Compare :

John stopped and Mary did as well. (John yes, Mary yes)
John stopped and so did Mary. (John yes, Mary yes)

John didn't stop but Mary did. (John no, Mary yes)
John stopped, but Mary didn't. (John yes, Mary no)


John didn't stop and Mary didn't either. (John no, Mary no)
John didn't stop and neither did Mary. (John no, Mary no)


So both "as well/so" and "either/neither" mean that the two were the same - but in the case of "as well/so" it's positive whereas in the case of "(not) either/ neither" it's negative.

Re: as well
 

Excellent answer. Thank you. But by

-"As well" means "too"

Do you think in the first sentence I gave, it's possible to use 'too' to replace 'as well'?(=someone else has stopped, but John did not stop too)

Somewhere in Michael Swan he mentions something like: (I don't have the book in my hand, sorry about that)

-You already have one cake. You can't have this one too.

Do you think this 'too' usage can be used as an analogy to solve my problem about 'as well/too'?

Re: as well
 

Look at what I said again - as well = too = so They're connectives of addition , meaning they can only be used to join two ideas which are the same - as in Swan's example:

You can have a cake and you can (have a cake) too/as well.
You can have a cake and so can you.

The meaning is yes + yes. For no + no you have the negative variants either/neither.
You can't have a cake and you can't (have a cake) either

But your first example is not yes+yes - it's no + yes. The ideas are different, not the same. So you cannot use connectives of addition - you need a connective of contrast - eg but

You can have a cake but you can't (have a cake) (No/Yes)

John didn't stop but Mary did. (John no, Mary yes)
John stopped, but Mary didn't. (John yes, Mary no)

Re: as well
 

Excellent answer. Thank you.