Matt Gagnon discusses the negative impacts of tariffs, citing historical examples like the Smoot-Hawley Tariff of 1930, which led to a 60% drop in American exports and prolonged the Great Depression. He argues that tariffs sound logical but are ultimately harmful, leading to job losses and economic contraction. Gagnon compares tariffs to illegal drugs, highlighting their initial appeal but long-term detriments. He also addresses the decline in U.S. manufacturing jobs, noting that while the number of jobs has decreased, the manufacturing industry is still growing. Gagnon emphasizes that the decline is due to technological advancements, energy costs, and market competition, not just trade policies.