I will Try, Try implies failure?

If you ask someone to come to a conference that you have put together and the reply you get the answer “I will try” dose that give you the assurance that they will be there? I guess you won’t be there if you are not committing, you either will or you won’t be there, there is no middle ground. There is no limbo just commit or deny it’s as easy as that. Don’t try ether do it or don’t. There are lots of failed things I can think back on by people trying. So when answering someone ether tell them you will or you won’t. If someone tells you that they will try asking them to commit or decline.
Brad west ~ onomoney