I'm wondering the subtle difference between possible and probable in this statement.

Possible means greater than a zero percent chance. Basically, something could happen. Probable means greater than a 50 percent chance. So something is more likely than not to happen. In this case, the article is saying this was not only possible (more than zero percent chance likely), it was moderately probably (probably slightly more than 50 percent chance likely).

Possible is about whether or not the thing could occur. It is a true / false type condition. Probable is about how likely it is the thing occurs. I roll a dice three times. It is entirely possible I roll 6-6-6. It’s not very probable though. I’m on my phone so it’s hard to switch between the comment and the picture, but it’s saying that an attack is very much possible, even if only a moderate chance of occurring. Essentially, before they put up the bollards (which are large obstructions) the large number of people in the French quarter meant that a terrorist in a car would be very able to perform a significant terror attack. So they put up obstructions to keep the cars out.

basically saying that it is able to happen but not that likely

Possible means something \*could\* happen, probable means it is not only possible but also \*likely\* to happen.

Probable means the chance of something happening is more than 50 % Possible = more than 0 %

Possible is how likely it *could* happen, probable is how likely it *would* happen.

possible = could happen probable = likely to happen Because of "highly" and "moderately", the meaning is subtle, but still exists. "Highly possible" = there's a good chance it will happen "Moderately probable" = I think it's quite likely to happen For example, a racing horse is faster than all the others, but sometimes will stop in the middle of the race. It has a very good *chance* of winning, but it's by no means certain. It's highly possible (that it will win), while moderately probable.

"probable" is a little different when you're referring to something random like a dice roll, vs something someone chooses to do. It's currently well below freezing where I am. I could go for a run today shirtless wearing just shorts. That's highly possible- if I wanted to, I could, and nothing would prevent me. But it's also not very probable - it would be very unpleasant for me so I'm not very likely to do it, even though I can.

I really like that sentence It's very nuanced. Nothing much has changed to affect the possibility of such an event, anyone who wanted to do it would not find it difficult.but it is improbable that someone would want to do it .

I disagree with a lot of the comments above. In this use case, “possible” is not an indicator of *how likely* the event is. One definition of “possible” is “capable of being achieved,” and that’s how it’s being used here. (“Probable,” on the other hand, *is* an indicator of event likelihood.) Another way of writing the circled text would be “[A vehicular attack] would be easy to do, but is only somewhat likely to happen.”