Friday, July 20, 2012

Believing What I Believe to be False

I talk a great deal about choosing different points of view and different rules of thought. But it may be objected that everything I say falls apart for the simple reason that we can not actually choose what we believe. That either the evidence is present that convinces us or there is not, we do not choose to believe a proposition.

It might be supposed that we imagine a boy named little Bruce. Little Bruce learns in school that triangles are shapes with three edges and three corners. He also learns that any triangle you imagine will have interior angles which add up to 180 degrees. Upon being told this, Little Bruce thinks through the matter for himself. Any widening of one angle in a triangle necessarily means narrowing the other angles, and no angle could ever exceed 180 degrees on its own, because then what was previously its exterior angle would become its interior angle. Thinking through different possible ways a triangle might have more than 180 degrees among its interior angles, he concludes that it is impossible, and then presumably puts his geometry homework down and settles in for a very sexless high school experience.

Now, could Little Bruce ever choose to believe that triangles with more than 180 degrees worth of interior angles were possible?

It would certainly be impossible for him to choose to believe it in the same way that he currently believes that the interior angles of triangles always add up to 180. Suppose that he believed this because teachers had always told him it were true and he viewed the world through the vantage point of presupposing “whatever teachers tell you is always true.” From that vantage point, he could not believe in a triangle with 181 degrees worth of interior angles because no teacher ever told him it was possible. Suppose he believed this because his own powers of reasoning led to him to believe it was true, and Little Bruce naturally saw the world through the lens of, “trust in your own powers of reason,” so he could not believe in extra-180 degree triangles because he could not picture how such a thing would be possible.

He could never change his assent or lack thereof to any proposition within the vantage point he used when he came to the point of view unless there was some kind of error or deficiency in his reasoning when he came to assent. Maybe evidence was lacking, or maybe he did not apply the rules of his vantage point correctly. But if all the evidence was available and the rules were applied correctly, it is impossible for him to change his mind, within the vantage point.

But now, let us suppose that while he still views the world through the lens of, “trust in your own powers of reason,” he then said, “but just for kicks, what would the world look like if I said, 'always suppose that you are insane.'” In this case, he could indeed believe in triangles that had more than 180 degree angles. He can not picture them, but that is just because his brain is broken. Maybe. Maybe that is more bad reasoning. In fact, drop the reasoning because it is all defective!

From this vantage point, he could believe. You may object that no one could coherently think from that vantage point. In that case, suppose he looked through the lens of, “things contrary to my reasoning powers are possible.” He could then believe in as many 181 degree triangles as he liked, but only from that point of view. If he ever went back to believing that he should always trust in his own powers of reason, then he would have to go back to believing that 181 degree triangles are impossible.

Within a set of presuppositions and axioms, the conclusions are what they are. You cannot choose what to believe, either the evidence points to something being the case or it does not. Vantage points can always be changed though, we can always change the presuppositions. This is how it is that we can avoid accepting seemingly obvious truths: we selectively change up our rules of reasoning.

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