There can be a pluralism of logics because Screen Shot 2017-09-23 at 10.55.59 PM.png whereScreen Shot 2017-09-23 at 10.57.58 PM is classical negation. This can be justified because  “1 Screen Shot 2016-08-19 at 2.33.44 PM 2″ and “1 is not 2” are basically the same statement. However “not 2” has different meanings in different logics, so 1 Screen Shot 2016-08-19 at 2.33.44 PM 2 means something different in paraconsistent logic (We’ll use DeCosta’s C1), we mark this difference with 1 Screen Shot 2017-09-23 at 10.58.22 PM 2, and claim that the difference between classical negation (Screen Shot 2017-09-23 at 10.57.58 PM) and paraconsistent negation (Screen Shot 2017-09-23 at 10.58.22 PM) is  marked Screen Shot 2017-09-23 at 10.58.10 PM. Hence Screen Shot 2017-09-23 at 10.55.59 PM.png.

I mentioned in a previous post that we cannot generalize this statement into Screen Shot 2016-08-19 at 2.33.02 PMbecause it is a contradiction. Nevertheless, a sense in which Screen Shot 2016-08-19 at 2.33.02 PMis true is the sense Screen Shot 2017-09-23 at 10.55.59 PM.png.

Now, vagueness is the situation where it is not clear if 1 Screen Shot 2016-08-19 at 2.33.44 PM 2. To illustrate, take this curve: graph_avg_weight1

here is vagueness on whether we have two or one “heaps”. This thing could be 2 or it could be 1 and so in a sense 2=1. How is this handled by logical pluralism? Paraconsistent logic would allow that A: “1 is not 2” and ~A: “1 is 2” has a sense in which it is true, while classical logic would explode. The reason for this is entirely based on the difference in negation. C1 creates a new sense each time a true possibility is negated, making the negation of a possibly true row in the truth-table have two senses, one in which the negation is true, another in which the negation is false.

(A Screen Shot 2017-09-23 at 10.57.58 PM ~A) Screen Shot 2017-09-23 at 10.58.10 PM (A Screen Shot 2017-09-23 at 10.58.22 PM ~A)

The point is that how you handle negation changes how vagueness is handled (or not handled). A difference in negation also gives rise to an entirely different logic. Vagueness can be described completely as a failed distinction/negation, so that even though we want “1 is not 2” vagueness makes this distinction fail. A different negation yields a different way distinction fails, but no logic “solves” vagueness completely. This is the mathematical relationship between vagueness and logical pluralism.

This may be made clearer with another example. Vagueness is the situation when a distinction fails, which can be described by the failure to distinguish = from Screen Shot 2016-08-19 at 2.33.44 PM, so Screen Shot 2017-09-28 at 1.30.38 PM.

Now for classical logic if vagueness renders 1 = 2 we can prove Screen Shot 2017-09-28 at 1.30.38 PM, likewise in paraconsistent logic there is no problem having Screen Shot 2017-09-28 at 1.30.38 PM as another non-explosive contradiction. this means in particular that Screen Shot 2017-09-23 at 10.57.58 PMScreen Shot 2017-09-28 at 1.34.47 PM and Screen Shot 2017-09-23 at 10.58.22 PMScreen Shot 2017-09-28 at 1.34.47 PM. Substituting, we get that things can get so vague we can’t tell the difference between Screen Shot 2017-09-23 at 10.57.58 PM and Screen Shot 2017-09-23 at 10.58.22 PM, in other words Screen Shot 2017-09-23 at 10.57.58 PM = Screen Shot 2017-09-23 at 10.58.22 PM. and from our previous statement Screen Shot 2017-09-23 at 10.55.59 PM.png we have Screen Shot 2017-09-23 at 10.58.10 PMScreen Shot 2017-09-28 at 1.34.47 PM and vagueness is now mathematically related to logical pluralism.

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