Some people sometimes mention that deduction conforms to the GIGO principle. I will here show that in a straightforward interpretation of that, it is false. “Garbage in, garbage out” is a metaphor or sorts. The mental image I form when I hear it is something like a huge machine that, when garbage is put into it, garbage comes out. Perhaps in smaller pieces. How can we apply this to deduction, that is, reasoning with deductively valid arguments? The most straightforward interpretation seems to be this: Deduction is some kind of machine, that when we put in bad data as premises, bad data conclusions comes out. What could bad data mean? The obvious candidate is false data, that is, false premises and false conclusions. What else could it mean? This interpretation thus means: All deductively valid arguments with false premises have false conclusions. This is simply false. Counter-examples are easy to come by and are given in most logic introduction textbooks, here is another:
“garbage in, garbage out” (GIGO) and deduction
“garbage in, garbage out” (GIGO) and…
“garbage in, garbage out” (GIGO) and deduction
Some people sometimes mention that deduction conforms to the GIGO principle. I will here show that in a straightforward interpretation of that, it is false. “Garbage in, garbage out” is a metaphor or sorts. The mental image I form when I hear it is something like a huge machine that, when garbage is put into it, garbage comes out. Perhaps in smaller pieces. How can we apply this to deduction, that is, reasoning with deductively valid arguments? The most straightforward interpretation seems to be this: Deduction is some kind of machine, that when we put in bad data as premises, bad data conclusions comes out. What could bad data mean? The obvious candidate is false data, that is, false premises and false conclusions. What else could it mean? This interpretation thus means: All deductively valid arguments with false premises have false conclusions. This is simply false. Counter-examples are easy to come by and are given in most logic introduction textbooks, here is another: