can you please explain from the economic point of view, why protectionism is bad? If sometimes it is sensible to protect some industries to avoid unemployment, loses of some professionals, death of the industry and decreasing independence? What do you think? tnx
To add to the other comments here - when you allow for free trade to prosper countries/regions tend to specialize in what they are good at producing/creating (idea of comparative advantage). This leads to better products created more efficiently. Note that this idea has no care for unemployment rates in certain countries, it simply states that as a whole we are all better off.
You may have heard that some people (often unskilled laborers) are "left behind" by globalization, particularly in developed nations such as the US (think auto industry). To think like an economist these people ought to re-appropriate their efforts to developing a skill that is useful in their new environment. However, that isn't always plausible for many people, which is where you can argue that government should step in and help them learn new and useful skills (preferable to protecting an inefficient industry).
Protectionism tends to dampen productivity and efficiency thus often leading to inferior goods that cost more to the consumer.
In theory, it is bad because its inefficient. You protect your inefficient industries, I protect mine, we all end up consuming less. We would all be better off with totally free trade...
But of course, there are many complications to this. It might be that an industry needs time to become efficient and you want to protect it in the meanwhile. Or it might be that the other country is not more efficient, but is just dumping their products o your economy until your firms close, after which they will raise their prices and extract a handsome surplus...
There is also this concept of creative destruction. Which basically means that old less productive technologies must die in order to free up resources to be made available to new, more productive technologies. It's analogous to pruning. But it occurs naturally in a free market economy and does not require management or government intervention.
Protectionism impedes the natural and beneficial process of creative destruction.