Indeed, but that is where we, as engineers, have to stand our ground, and say "not possible". A good executive will then ask, "what do you need to meet the goal?" and you can start to have a productive conversation.

I could go on about this, I have had this argument many times and I have yet to have highups question my competency or dismis my arguments. I do always leave the door open with something along the lines "I can hire 4 developers and 1 QA, minimize time to shipping, but we will drop all current support. We will have significantly more bugs in 1.0 and if they want any major changes a rewrite is needed". If that is what they want, I'm a fool for not delivering, but I also know to start looking for a different job.