Its a bit of a complex topic, but in basic terms reactionary thinking is kneejerk reaction, what "feels right" without broader analysis. The popular surface level, like how people complain about trans people in sports cause it "feels unfair", but when you look at the actual numbers there such a small section of out trans people in general, and even then they do pretty regular on average. Or how you here how believe all women will somehow make it "dangerous" for men dating, when in reality false accusations form less than one percent of cases, but one in four women experience assault. Whereas dialectical thinking is the thought that larger processes and symptoms influence outcomes, and one should take a step back and analyse the context and direct facts about something through critical thinking before coming to a conclusion. Like how study after study have proven that the number one factor contributing to a person engaging in violent crime is poverty, not just a person being born bad. Or how despite the narrative, immigrants commit crime at a lower percentage on average than natural born citizens. But since it dialecticalism is a much bigger analysis and uses a fair amount of hypothetical and philosophical thinking and you end up getting a fair amount of groups believing that their hypothetical analysis is best, such as you get with different philosophers.