Hero of Alexandria (born around 10 AD) is credited with developing the first steam engine, the first vending machine and the first known wind powered machine (a wind powered musical organ). Given the revolutionary impact of the steam engine centuries later, it might be wondered why the Greeks did not make use of these inventions in their economy. While some claim that the Greeks simply did not see the implications, others claim that the decision was based on concerns about social stability: the development of steam or wind power on a significant scale would have certainly displaced slave labor. This displacement could have caused social unrest or even contributed to a revolution.
While it is somewhat unclear what prevented the Greeks from developing steam or wind power, the Roman emperor Vespasian was very clear about his opposition to a labor saving construction device: he stated that he must always ensure that the workers earned enough money to buy food and this device would put workers out of work.
While labor saving technology has advanced considerably since the time of Hero and Vespasian, the basic questions remain the same. These include the question of whether to adopt the technology or not and questions about the impact of such technology (which range from the impact on specific individuals to the society as a whole).
Obviously enough, each labor saving advancement must (by its very nature) eliminate some jobs and thus create some initial unemployment. For example, if factory robots are introduced, then human laborers are displaced. Obviously enough, this initial impact tends to be rather negative on the displaced workers while generally being positive for the employers (higher profits, typically).
While Vespasian expressed concerns about the impact of such labor saving devices, the commonly held view about much more recent advances is that they have had a general positive impact. To be specific, the usual narrative is that these advances replaced the lower-paying (and often more dangerous or unrewarding) jobs with better jobs while providing more goods at a lower cost. So, while some individuals might suffer at the start, the invisible machine of the market would result in an overall increase in utility for society.
This sort of view can and is used to provide the foundation for a moral argument in support of such labor saving technology. The gist, obviously enough, is that the overall increase in benefits outweighs the harms created. Thus, on utilitarian grounds, the elimination of these jobs by means of technology is morally acceptable. Naturally, each specific situation can be debated in terms of the benefits and the harms, but the basic moral reasoning seems solid: if the technological advance that eliminates jobs creates more good than harm for society as a whole, then the advance is morally acceptable.
Obviously enough, people can also look at the matter rather differently in terms of who they regard as counting morally and who they regard as not counting (or not counting as much). Obviously, a person who focuses on the impact on workers can have a rather different view than a person who focuses on the impact on the employer.
Another interesting point of concern is to consider questions about the end of such advances. That is, what the purpose of such advances should be. From the standpoint of a typical employer, the end is obvious: reduce labor to reduce costs and thus increase profits (and reduce labor troubles). The ideal would, presumably, to replace any human whose job can be done cheaper (or at the same cost) by a machine. Of course, there is the obvious concern: to make money a business needs customers who have money. So, as long as profit is a concern, there must always be people who are being paid and are not replaced by unpaid machines. Perhaps the pinnacle of this sort of system will consist of a business model in which one person owns machines that produce goods or services that are sold to other business owners. That is, everyone is a business owner and everyone is a customer. This path does, of course, have some dystopian options. For example, it is easy to imagine a world in which the majority of people are displaced, unemployed and underemployed while a small elite enjoys a lavish lifestyle supported by automation and the poor. At least until the revolution.
A more utopian sort of view, the sort which sometimes appears in Star Trek, is one in which the end of automation is to eliminate boring, dangerous, unfulfilling jobs to free human beings from the tyranny of imposed labor. This is the sort of scenario that anarchists like Emma Goldman promised: people would do the work they loved, rather than laboring as servants to make others wealthy. This path also has some dystopian options. For example, it is easy to imagine lazy people growing ever more obese as they shovel in cheese puffs and burgers in front of their 100 inch entertainment screens. There are also numerous other dystopias that can be imagined and have been explored in science fiction (and in political rhetoric).
There are, of course, a multitude of other options when it comes to automation.