APAD: What you don't know cannot hurt you

What you don't know can't hurt you.

 This is a common idiom that suggests that ignorance can be a buffer against negative emotions or consequences. However, this idea is often debated, as there are situations where not knowing can be harmful or detrimental. 

If someone is unaware of a problem, misdeed, or potential danger, they cannot be negatively affected by it, at least in terms of worry or anxiety.

Some people use this saying to justify not telling someone about something, especially if they believe it will cause them distress. There are many situations where not knowing can lead to real harm, such as not knowing about a medical condition or a dangerous situation like a car accident on an on-ramp. Not knowing about a potential opportunity can mean missing out on it. Not knowing about the potential consequences of an action can lead to negative repercussions. 

The saying dates back to at least the 16th century, with variations appearing in literature, according to the American Enterprise Institute. 

In conclusion, while the idea that ignorance is bliss has some merit, it's not always true. There are many situations where knowing, even if it's unpleasant, is better than remaining in the dark.