Second, [Lee Kuan Yew] learned that fear of brutal punishment can deter crime:
The Japanese Military Administration governed by spreading fear. It put up no pretence of civilised behaviour. Punishment was so severe that crime was very rare. In the midst of deprivation after the second half of 1944, when the people half-starved, it was amazing how low the crime rate remained. . . . As a result I have never believed those who advocate a soft approach to crime and punishment, claiming that punishment does not reduce crime. That was not my experience in Singapore before the war, during the Japanese occupation or subsequently.
On the other hand, there are plenty of sources that claim that harsh punishment does not deter crime, e.g.:
And starting in the early 1990’s, crime began a two decade long decline that the public seems by and large not to have noticed. Yet there’s little evidence to suggest that the threat of punishment—even the threat of very harsh punishment, such as the death penalty—is responsible for the drop in crime. A massive 2014 study undertaken by the National Research Council announced that one of its “most important conclusions is that the incremental deterrent effect of increases in lengthy prison sentences is modest at best.” Put in less academic-ese: Threatening people with increasingly harsh punishments doesn’t discourage crime.
What explains the differences in the two viewpoints? I can think of many possible explanations, but I can't seem to find any sources to back them up - e.g. it's commonly asserted that it's the perception of how likely one is to be caught that deters crime, but I can't find any sources that say the Japanese Military Administration are very good at catching criminals. Similarly, Lee Kuan Yew's description of Japanese brutality implies that terror is effective at deterring crime, yet terror seems at least closely related to harsh punishments, and so is explicitly contradicted by the second source.