What was it about the Industrial Revolution that caused the principles of classical liberalism to be modified?
Classical liberalism is a philosophy that advocates as much freedom as possible for people to act as they wish without government interference. This includes the right for people to act as they wish in the economic sphere and their right to try to influence the government. It is in many ways dependent on the idea that all people have equal opportunities and are independent. When the Industrial Revolution came along, people became less equal and less independent. This caused problems for classical liberalism.
In an industrial society, there tends to be inequality. People who own large companies have much more money, much more power, and much more influence than those who work for them. Because of this, such people could come to dominate a society that was based on classical liberalism. They could use their power, for example, to abuse workers. Because of this, classical liberalism had to be modified to allow for more government intervention in the economy. The government had to step in to prevent these powerful industrialists from doing things that would hurt those with less power.
The Industrial Revolution, then, caused a modification of classical liberalism to allow for more governmental regulation of the economy.