Sometimes I ponder how we think

Sometimes I ponder how we think.

How do we jump to conclusions? How do we argue?

Logic: a tool in argumentation. Simple syllogisms may suggest the following:

P1: All ravens are black

P2: This bird is a raven.

(raven= black)(raven=bird)   ->all ravens are birds.

C1: This bird is black T

The conclusion is valid because it is covered in the all-statement; it is a deduction from the larger to the more specific.

P1 All ravens are black

P2: This bird is black

(raven=black) (bird=black)  -> all birds are black?

C2 This bird is a raven. F

We see the connection between them, but there is no causal effect. They do not lead to any new deduction. They are separate statements. C2 is false.

P1 All ravens are black

P2 All ravens are birds

C3: This raven is black T (All ravens are black birds)  (raven= black)(raven=bird)  

C4: All birds are black? F (All birds are not ravens) (raven=black) (bird=black)(?) 

C4 is false from two perspectives: it does not concur with reality; it does not follow, logically. C4 seeks to induct a general statement about all birds based on the example of one bird. The premises speak about the ravens in particular. There is no information about birds in general.

P1: All ravens are black (raven=black)

P2: Black is not a colour (colour ≠ black)

C5: Ravens are lacking colour/ have no colour/are colourless?

Is this last syllogism valid? What does it really say? Does it prove that colourless birds fly about; and how can we see anything colourless? Does the statement about ‘black’ indicate a ‘lack’? It may not be defined as a colour, but does that make the bird without any visibility? What is wrong with C5? Is it really based on the premises?

 

  

         Are we using arguments of these kinds?