This is an interesting question partly because it is a complex query dressed up in a simple manner. There are many terms here which require a great deal of unpicking before being able to arrive at any sort of warranted conclusion. As a result, there are some assumptions that will have to be made in order to analyse these concepts in a concise framework. Here we have terms like ‘reason’ (and qualified as ‘very strong’), ‘belief’ and ‘false’. In other words, this essay is primarily an epistemological investigation into reason, belief and truth. I will first, and somewhat briefly, define what I feel qualifies as truth before looking at what it would take to have a warranted belief in a false (untrue) proposition. My approach after this will take on a twofold tack. Firstly, I will attempt to establish a reliable method of arriving at a truth. In other words, if one uses what can be deemed as an unreliable epistemological methodology[1], then one is not warranted (i.e does not have very strong reasons) in believing a proposition, especially if another agent can somehow reliably deem this proposition as being false. Secondly, I will look at whether one can have a defensible epistemological method which arrives at a belief in a proposition that is untestable[2]. Thus both prongs can assume that the agent is not aware that the proposition is false and may not, in some instances, even have any way of knowing this. Finally, I will explain that the word and notion ‘reason’ can take on two different senses (one of causality and one of rationality) in order to conclude that if one uses an unreliable epistemological method or one which leads to an untestable belief in a proposition, one cannot have very strong (rational) reasons for believing in something although it is false.
It is important to set out epistemologies from an axiomatic starting point. There is no better place to