Yakub asked:
I haven’t recently thought about something that would be a reason to not do a particular action. However I forgot what it was so I’m not sure if it was right. Let’s call this thought thought A. However this thing refuted a thought I had in my head (let’s call it thought B) that I was allowed to do the thing that thought A ruled out. Now I know for sure what thought B is, yet I don’t know what thought A is although I’m sure it refuted thought B. Yet I don’t know if it refuted it correctly. I’m not even 100 percent sure thought B is correct but I do remember it. So should I not do the thing or am I still allowed to do it? Please do not say it is my choice or something like that. I want the answer of what would be the smartest option.
Answer by Geoffrey Klempner
Yakub, I know exactly what you mean, although I am pretty sure that this is the very first time we have had this question. So, well done for that!
I hope you don’t mind my rewording your question a little, although I can imagine many readers still puzzling over this. The smartest option? Speaking as someone who is more than a little forgetful, the smartest option is to wait until you remember what thought A was. Or maybe it’s written down somewhere, e.g. in a notebook. Or ask someone who knows you well.
Seriously, this could be a matter of life and death!
The easiest way to illustrate your problem is with examples. Here’s one: Across town is a shop that sells my favourite brand of cigars. I don’t visit there very often, but when I do I like to restock my humidor. Let’s say, my humidor hasn’t been restocked for a while, and having nothing better to do I decide to pay a visit to my cigar shop tomorrow. But there’s a nagging thought in my head that I can’t quite remember. What was it? The next morning I wake up, and remember that the last time I passed my cigar shop on the bus, it had closed down and is now a nail parlour!
If I hadn’t remembered what my thought A was, I would have journeyed across town, discovered that the cigar shop was no longer there and returned home disappointed. So not a life-or-death matter. But this illustrates one aspect of your problem, which has to do with risk and consequences. If the likely risk is not very great — in this case just a wasted journey — then if you have a strong enough reason to do B then by all means have a go.
But let us now imagine a different case. Feeling a bit under the weather I pay a visit to my local physician. I describe my symptoms. The doctor takes my pulse and temperature, gives me a short examination and prescribes drug X. ‘Take this three times a day, and you will feel better in no time.’ But there’s a nagging thought in my head. And then at the last minute I remember: ten years ago when I was in hospital, I was told by a consultant that I am allergic to drug X and just one dose could kill me!
These are elementary examples, but they illustrate the point. A more realistic scenario — one that I myself have experienced — might be something like this. I want to upgrade the system on my desktop computer. There’s a particular improvement I want to make, that would make my desktop run a lot faster, but didn’t I try this a year ago? What exactly went wrong? Or did I consider making the upgrade and then change my mind when I came across a warning on Google? I can’t remember. So, what are the likely consequences? I can try again, and discover that the upgrade doesn’t work. That’s two hours wasted. Or I can try again, and destroy my hard drive, losing all my precious files. The question is: am I willing to take the gamble? In this case, the best option might be to search Google before trying anything else.
In short, my answer to your question is, it all depends on the circumstances. Try to remember. Gather what information you can. It is a matter of your choice, whether you go ahead with the action or not, but this is not not an arbitrary choice. You have to consider the possible consequences of your proposed action and make a judgement.
Ask a Philosopher 
