The largest issue that thomas aquinas attempts to prove in his summa theologica is the existence of

God

Explanation:

In his Summa Theologiae Ia 2.3, Aquinas provides five proofs for the existence of God, famously known as the five ways. He distinguishes different perceptible events and then ventures to prove that their cause is none other than God. The events Aquinas mentions are motion, the existence of efficient causes,  the reality of contingency, the different grades of perfection in the natural order, and the end-directed activity of natural objects.

when a country suffers, for example, a drought period, the market product is affected for a low offer, in this case, potatoes; the government has to tax to the households, which have to give more money for the potatoes which they consume, that situation make them consume substitute goods even through loans, it could increase the financial market movement and the inflationary phenomena, the business has to increase salaries in order to the employees could buy a more expensive food (potatoes) and in order to inflation tha business had to buy expensive supplies in the factor market, while the rest of the world have to gain more money to consume the same amount of potatoes.

increase in population