What technological/economic factors triggered the Industrial Revolution?

The Industrial Revolution was due in large part to the introduction of "engines," specifically the steam engine, and the internal combustion engine.

This allowed for the substitution of fuel as sources of energy (coal generated steam or steam engines, oil drove internal combustion engines) on a much larger scale than human or animal power. In essence, human beings were freed up to manage high-powered "engines" (and "machines" driven by engines) in factories, instead of having to put up a large part of the labor power on a much smaller scale.

Accompanying these changes was the development of banking, which allowed many "small" deposits to be combined into loans for the devlopment of factories and other large scale enterprises, to corporations that allowed people to invest in these enterprises with "limited liability."

This sequence is best represented by the industrialization branch of the game Civilization II, from steam engine, to railroads, industrialization, the corporation, (oil) refining, and (internal) combustion.

The industrial revolution occurred as a result of scientific advances in Europe. Specifically the Steam Engine and related Manufacturing Technology. However the Industrial Revolution began specifically in Britain, since wages in Britain were significantly higher than on the continent. This disparity increased the incentive for British businessmen (vs continental European) to invest in labor saving machines, which began the Industrial Revolution.

Unprecedented scientific advancements allowed economics to favor mechanization and spawn the Industrial Revolution.

The knowledge necessary to build the machines that backed the industrial revolution (notably, steam engines) had been around for quite a while before that (ancient Greeks were fully aware of how to use steam to move things); but it had never been used widely for a variety of reasons:

• Slaves were available to work for free (or at a very small cost); so, why bother with engines at all?
• There was very little population compared to today, so there was no real need to grow a lot of food or mass-produce things.
• And, anyway, a lot of people were just too poor to buy anything; so why bother with mass production when only a few people were actually able to buy something?

In the short run, human labour is vastly cheaper than designing, building, running and mantaining machines, which instead leads to much greater efficiency in the long run. What actually started the whole thing were changing social and economic factors, which made an industrial economy worthwhile.

It's a classic question of why the industrial revolution happened when and where it did. And answers range to everything from "Good Cannon makers" to "Because the British drank tea!"

It's likely that the question is impossible to answer conclusively. But what I would like to do is to set up a number of prerequisites for an industrial revolution. It's not certain that an industrial revolution will happen when these prerequisites are met, but I do think they are required, and I also think the 18th century Britain is the first time in history where they all have been fulfilled at the same time.

1. High agricultural yield, leading to cheap labour

This is what Steven Drennon talks about in his answer. The British Agricultural revolution led to farms being able to produce more food and feed more people. As a result, the population in cities increase, and there is a lot of labour available.

2. Technological ability

The ancient Greeks invented steam-powered toys. Why didn't they invent a steam engine? Because they didn't have the technology. The first attempts at steam engines in Britain and France failed, because the materials weren't up to the job of handling steam pressure. Also Watt could not have invented the condenser, and made the steam engine a much more economical alternative, unless he had understood boiling and condensing and how related to the different temperatures in the machine.

3. A capitalist economic system

In addition to a work force, you also need inventors who invent, industrialists who run things and investors that provide the money.

Point 1 and 2 in turn has a common prerequisite:

4. A scientific method

You can't get high crop yields if you think the most important part of the crop yield is praying to gods or making fertilizer by burying rams horns by the full moon. You will not learn the laws of thermodynamics if you think that converting water to steam is a form of magic.

And all of the above have a last prerequisite:

Liberty

1. and 3. needs economic liberty; private ownership of land and other means of production, and the right to do what you think is best to make money and invest that money.

2. and 4. needs liberty in ideology and thinking. The liberty to say that earth may not be in the centre of a theological universe, but zip around all by itself in a universe ruled by mechanics.

3. Also has a final prerequisite:

5. A big trading network

So there are people that can accumulate wealth that can be invested in industry.

There is also an argument that you need a good source of energy, ie coal. And that aragument is that late medieval and renaissance Netherlands had pretty much all of the liberty requirements fullfilled, but still did not get an agricultural revolution. But perhaps it was missing the natural resources needed. On the other hand I have also seen the argument that it simply was too early, the science and technology wasn't there yet, when the Netherlands had liberty and money.