(Next week I will consider a response from Hume)
In Hume’s work Enquiry Concerning Human Understanding he develops a well thought out and developed picture of what human understanding looks like. In this picture we can see that human understanding can only reason about two things; matters of fact and relations of ideas. Hume describes relations of ideas (ROI for short) as being like mathematical truths. These relations can be demonstrated and understood purely through thought and no physical objects would need to exist for any of these things to be true (truths about circles and triangles for example) and they are demonstrably true (if you were to imagine there contrary you could arrive at a contradiction). Next, there are the matters of fact which have contingent truth values. The nature of matters of fact implies that we cannot be as certain of them since we can always imagine the contradictory state of events (e.g. “the sun not rising tomorrow” and the contrary that “the sun will rise tomorrow”; both seem possible). Hume then reasons that we can only arrive at matters of fact by cause and effect reasoning. From here Hume doubts cause and effect which launches his whole skepticism.
It seems like the test he develops to distinguish between MOF and ROI isn’t sufficient enough to stop some apparent MOF from being ROI’s as well. This is my problem.
Essentially, I see Hume’s reasoning to be as follows:
- If one had strong grounds for believing MOF to be true then one could establish the truth of MOF the same way one could establish the truth of ROI.
- It is not the case that one can establish the truth of MOF the same way one could establish the truth of ROI.
- Therefore, it is not the case that we have strong grounds for believing MOF to be true.
The argument is a very clear modus tollens argument so the validity is not in question. The problem with the argument is premise 2. Hume does not set up a good case for the truth of this premise and it has to do with the origins for his belief in premise 1. Let’s take a look at the justification for each premise.
Hume asserts the truth of premise 2 explicitly here “Matters of fact, which are the second objects of human reason, are not established in the same way; and we cannot have such strong grounds for thinking them true.”(Hume 11) In this quote we actually have Hume asserting premise 2 and 3 in conjunction but it is important to see the deductive work being done in the very same paragraph that implies premise 1. Premise 1 is derived from a test that Hume does that I call the imaginability-of-contraries (IOC for short) test. The test says that if one can imagine the contrary of a statement without implying a contradiction and can do it as easily and clearly as if it conformed to reality then that statement does not have a strong and reliable ground for its truth. Hume’s example involves whether the sun will rise tomorrow or not. One can easily imagine either one and not violate the two conditions set out by IOC test. I assume, because of the quote above, that this test is also Hume’s distinguishing factor between the MOF and ROI since it seems that ROI do not pass the IOC test. One, for example, cannot imagine the four sided triangle or the triangle whose sum of all its angles adds up to more than 180 degrees without implying a contradiction. When one asserts “the sun will not rise tomorrow” they assert something that passes the IOC test since it doesn’t imply a contradiction and one can easily imagine it and it would be clear as if it could conform with reality. This is where I believe Hume is fundamentally flawed.
The IOC Examined (My Argument)
Mathematical truths fail the IOC because they are definitions of what it is to be a certain thing. Conducting the test is like me asking you to imagine the contrary of any arbitrary definition; obviously any contrary statement would imply a contradiction if that statement is the definition of something. Let’s say shadows are by definition the dark area or shape produced by a body coming between rays of light and a surface. Imagine a non-dark shadow (a well-lit shadow) it is implies a contradiction. Let’s say, by definition, for a star to be the Sun then it needs to be a star exactly 92,960,000 miles away from earth, the earth needs to be revolving around it at exactly 1 revolution per 365 days, etc. (add any other physical facts that define our sun distinctly from all other stars) and have part of the definition be that it will “rise” tomorrow (or more accurately that we continue to revolve around it) then by definition the sun will rise tomorrow. Now I cannot assert the statement “the sun will not rise tomorrow” without implying a contradiction. If I tried to assert that some sun was not to rise tomorrow it would be nonsense, we wouldn’t even be talking about the same object since that’s what it is to be the sun.
What about the second half of the test involving the imaginability of contraries? Doesn’t this say something about the sun since the numerically identical star to our sun can perhaps stop being our center point of revolution thus making our imagining the contrary of “the sun will rise tomorrow” seem plausible even given the definition of sun? It is true that this seems different from the triangle since one cannot imagine a four sided triangle in any sense at all. I would then implore the questioner to look at the shadow and try to imagine a light shadow. Not a relatively light shadow, I mean a shadow of light. This is simply impossible since the definition of shadow is not like the sun. The definition of shadow does more than point out what it is to be something at a given time in a given set of circumstances (like the star who is only our sun when we are revolving around it) but it truly defines what it is for a thing to be that thing. Shadows are an area of non-light (lack of light) and thus one cannot imagine the contrary for shadow. It seems plausible that one cannot talk about the contrary of shadow without talking about a completely different object. Thus we have a matter of fact, namely the definition of shadows, which fails the IOC test.