We've all had the sensation of intuition. "I don't know why, but this doesn't feel right" or "I just know that this will work." We bet on a horse that "I've just got a feeling is bound to win" and are shocked when it doesn't.
We revere this sensation as though it is some deeper truth– more true than other evidence.
This is a false view.
The best way to think about intuition is in a similar way to how we think about sight, sound and other more 'direct' senses. We know that for the most part our sight is pretty good for what it has emerged to do. We can navigate our world, find what we are looking for without bumping into things. We rely on our sight to keep us safe. So far so good. However, we also know that our eyes can deceive us.
What we see isn't a photograph of what is there, but a constructed - imagined - representation of what is most likely to help us navigate. Our brain's best guess. adjusted for usefulness. We've all seen various visual illusions where, for example, two equal lines look different lengths based on how the line is positioned. Because we can measure the truth with a ruler we accept that our eyes are wrong, marvel at the sensation and go about our day.
We tend not to be this scientific with 'intuition' because it is difficult to measure the accuracy against anything objective.
I coach my clients to think of intuition like a higher level aggregation of other senses and memories that provides a 'felt measure of confidence'. Our brain is looking to predict safety. It makes a guess (prediction) measures this against the sensory data (light, sound etc) and memory patterns (how well does this data match existing memory patterns and what do those patterns tell us about how safe we are).
The nagging sense that something isn't right is your brain saying "there is something about this that doesn't allow a prediction of safety" or "there is something about this that is similar to a previous dangerous experience" both of these will produce an intuition of nagging doubt. Such doubt is worth listening to, acknowledging and in the case of making a risky decision or action, worth stepping back and checking before jumping.
However, you can see a few ways it can be wrong. For example, what if the person you feel uneasy about just happens to look like someone who caused you harm 20 years ago. Your brain may find 'something fishy about this person' for no other reason than the coincidence of appearance.
What if the nagging doubt is about something you know to be on balance good for you, such as establishing a new exercise habit. But when your brain 'checks' with memory patterns for what this might mean for you and doesn't have any evidence for safety having never joined a gym before, or finds risk to what I consider normal or good ("I don't want to be end up like one of those gym junkies"), you can end up letting your "it just didn't feel right" to be an excuse for not acting in your best interest.
My message is pay attention to your intuition. It is powerful and helpful for the most part. If your brain says "slow down and check" then listen! Especially when it comes to physical safety.
Take a precautionary approach– if you feel 'too confident' you probably are. So check yourself, check evidence, look more closely, and think further into the future– "how is this likely to play out?".
If you feel danger or unease - act to make sure you and those around you are safe first – seek additional sources of evidence to help you determine the risk more clearly.
Intuition is a higher level sense so use it. However, in a competition between "good science" and "my gut"– science wins regardless of how I feel about it.