my son's mom remarried into a house with an american bulldog.  one
infant one 8yr old son, one chihuahua.  dog seems mildly jumpy but
nice to me. he growled and was aggressive in attack mode with my
nephew at the front door - a stranger to the dog, about 3 months ago.
could this dog attack my son or the infant in the house? or the
chihuahua? it is a male bulldog two and half or so yrs old.

Sounds like the dog is fine
- That it likes you in a high stress encounter shows good/bad/lack of taste

The fact that the 'rat dog' is still alive testifies to its (the
Bulldoggs) peaceful nature.

Most likely the dog will raise Cain if a burglar comes in, and sink
his teeth into somebody attacking 'my son's mom remarried' son
(that convolution foxed me for a bit)

Check out your nephew - he might be a nasty piece of work
- dogs can be better judges of character than humans
- always double check

We have a pitt bull and a baby, and they get along fine. Most of the
bully breeds are really quite people friendly, in spite of the
reputation. However, you should observe how the dog acts around the
boy in particular, and around people in general. Is the dog dominant,
or submissive? Can you take his food away from him, or does he guard
it? Is the dog fixed? I think the best thing would be to talk to you
son about how to act around the dog, eg what hackles up means, dont
pull his ears or tail, and to "be like a tree" - (stand still, hands
covering face, but calm) if the dog gets rowdy. Getting him to teach
the dog tricks would be good for both of them.

What does your son say?  Does he like the dog.  If he does and the dog
plays with him than I'd say the pups okay.

excellent comment particularly from quantum and just 4 fun, do you
have any other specific advice?  my son actually likes the dog. he is
dominant and hyperprotective with his dog bones.

you responded and said that the dog was hyperaggresive toward bones
most people think that if the dog is ok with people around his food
and whatever he will be fine with bones but most aernt and people dont
realize that bones are in a whole different category than just dog
food i have 4 pit bulls and i wouldnt even take the chance of giving
my dogs bones around the other dogs company or my daughter its not
worth putting your dog in that position because of their instincts