This is the 6312th most frequent Chinese word.
惑
"惑" means "confuse" or "bewilder."
In this instance, '惑' directly refers to 'doubts' or 'confusions' as an individual character.
古人常用哲学解决心中之惑。
Ancient people often used philosophy to solve their doubts.
In this context, the word '惑' is part of the word '疑惑' which means 'confusion' or 'perplexity'.
他感到疑惑,因为事情发展并不如预期。
He felt perplexed because things didn't develop as expected.
Here, '惑' is part of '诱惑', meaning 'temptation' or 'enticing'.