I consider myself a person with reasonable intelligence. In my job, I require a lot of critical thinking. I am good at think laterally, but sometimes I feel I missed important critical evaluations of a simple problem. Then, I start to doubt my own intellect and rationality.
Is critical thinking associated with IQ?
Critical thinking is an ill-defined concept in the cognitive sciences, so this question most likely has as many answers as there are measures of IQ and critical thinking. An accessible introduction to the literature is available here, with the general cognitive conception of critical thinking given as follows:
... the mental activities that are typically called critical thinking are actually a subset of three types of thinking: reasoning, making judgments and decisions, and problem solving. I say that critical thinking is a subset of these because we think in these ways all the time, but only sometimes in a critical way. Deciding to read this article, for example, is not critical thinking. But carefully weighing the evidence it presents in order to decide whether or not to believe what it says is.
With that said, there appears to be some empirical support for a relation between cognitive ability/IQ and critical thinking ability, at least within a dual-process theoretic framework. Sá, West and Stanovich (1999) reported:
Participants high in cognitive ability were able to flexibly use prior knowledge, depending upon its efficacy in a particular environment. They were more likely to project a relationship when it reflected a useful cue, but they were also less likely to project a prior belief when the belief was inefficacious.
I've provided a link to the PDF my references, since they refer directly to cognitive ability rather than IQ, and the equivalence is only made clear in their Method section.