I don't want critique per se, but...
I have an essay (around 800 words) for my History of Economic Thought class due Monday and as it will be the first time ever I'll hand in schoolwork in English, it'd like to have it checked by native speakers. (This is allowed, right? I didn't see anything against it in the community rules...)

I need to know about any grammar and/or spelling mistakes and also just how awkward and confusing it is. As for the actual historical value of this, don't even bother... Also, as I'm in England, please slap me if I'm using any American phrases.

Was Adam Smith justified in using the term "mercantile system" to summarise the work of his predecessors?

While the term "mercantilism" wasn't used until Adam Smith's Wealth of Nations, a common set of beliefs and trade policies was indeed in existence in many European countries during the 17th century. Two key ideas of this system were that gold and silver where the source of wealth, so that a country could be deemed wealthy and powerful when it held precious metals in sufficient amounts, and that any gain made from trade was the loss of another country. These ideas emerged as countries were concerned with national power and getting enough funds to lead war, which explains the perception of every other country as an enemy. As restrictions were put on exports of gold and silver throughout Europe, many writings that Smith would consider to pertain to "mercantilism" were issued by merchants that wanted to protect their business and for whom the aforementioned restrictions were a hindrance to trade. Their main argument was that a country could benefit from trade as long as it exported more commodities than it imported, so that gold and silver would enter the country in payment for the excess imports. Thinking of a "balance of trade", an idea that can be traced back to the 14th century , became systematic and writers such as Mun suggested that placing high duties on imported goods and low ones on imported goods would be a way to keep exports in excess in reference to imports. As such, the term "mercantilism" could be used to describe this widespread set of economic policies.

But while common ideas existed in various countries, these beliefs were never a "system" or an organised thought currant. None of the many writings on trade issued during the 17th century pretended to be a theoretical work like the Wealth of Nations would be. Smith was the one to elaborate a model of what the "mercantile system" was to summarise the work of his predecessors, quoting Mun's England’s Treasure by Forraign Trade as a key work of "mercantilism", but Mun himself never had the pretension to be, neither was he considered as, the head of a thought currant.

To emphasise this point, it is to be noted that other important figures that could be qualified as "mercantilist", though they wouldn't think of themselves in these terms, had many points of divergence with Mun, and as such couldn't be said to fit in the "mercantile system" described by Smith. For example, Jean-Baptiste Colbert, the French minister of finance under Louis XIV, was a representative of mercantilism "in the narrow sense of the term" in the sense that he did everything he could to protect the state's monopolies and greatly favoured exports in an attempt to keep a favourable balance of trade. He used state authority to regulate the whole of the economy, were it by bringing the guilds under state control, offering bounties to encourage domestic manufacturing, building roads and canals to facilitate domestic trade, building a navy and a merchant marine to improve shipping of goods or expanding the French colonial empire to secure new monopolies. His purpose, namely make France into a self-sufficient country, was altogether different from Mun's, a merchant advocating laissez-faire, understood for all purposes and intent as the freedom to export, and as such can't be said to be part of a "mercantile system" built around Mun's writings.

Finally, an interesting duality in Smith's analysis has been noted by D.C. Coleman. On the one hand, Smith believes in an "invisible hand" that will ensure that while people search for their personal interest, the interest of the nation will be achieved. On the other hand, the "mercantile system" is said to have been brought about by merchants blinded by their "monopolizing spirit", though they were undoubtedly pursuing their personal interest. While Smith's concern with individual liberty is philosophically appealing, his determinist view of history and the place the "mercantile system" takes in the order of things is not entirely satisfactory and as such the idea of talking about such a system could be called into question.

In conclusion, while using the term "mercantilism" could be justified to describe a set of beliefs and policies common to the whole of Europe during the 17th century, by using the phrase "mercantile system" Smith gave a coherence to the work of his predecessors that it didn't have and deliberately simplified it, using Mun's pamphlet as an epitome of what the "mercantile system" was, to bring it down more easily.