Robot arithmetic: can new technology harm all workers or the average worker?

It is well-established that new technology can cause large changes in relative wages and inequality. But there are also claims, based largely on verbal expositions, that new technology will harm workers on average or even all workers. Using formal models (which impose logical consistency and clear links between assumptions and conclusions) we show – under plausible assumptions - that new technology will cause average wages to rise if the prices of investment goods fall relative to consumer goods (a condition supported by the data) and if the new technologies do not lead to a fall in market competition. Some groups of workers must gain but others may be harmed. However, if workers can freely choose their occupation, or redistribution among workers is possible, all workers can gain