I think Tommy is on the right track. Machines do not have the ability to reason or be aware of their own existance, but neither do animals. Every animal on this earth looks and acts the way it does because natural selection has chosen that phenotype as the most fit for its environment. So in this way, how are animals not machines? To take this idea a step further, humans are animals as well. Just because we have the ability to reason and be conscious now does not mean that we have always had that abilty. There must have been a time in human evolution when humans did not have the ability to be aware of their own existence. At that time, humans must have been machines since they did not have that ability. Fortunalty, somewhere along the evolutionary course, it was adaptive for humans to possess the brain pathways that allow for consciousness. When this happened did humans suddenly stop being machines and rise into a higher order above the machines of which they are made? I think that all living organisms are biological machines, though some may be more complex than others, and none are perfect.