The Art of Logic

The primary aim of normal language is communication, whereas the primary aim of logical language is to eliminate ambiguity.

A is a sufficient condition for B. B is a necessary condition for A. • A is true only if B is true. Only if B is true is A true.

Time and causation flow in one direction only, and so does logic, and we must be careful not to make errors in direction.

Like time, logic has a direction and we must not try to violate it.

The two are linked, but in mathematics they are particularly cyclically linked.

I will keep coming back to is that you can be alogical without being illogical, and indeed being alogical is unavoidable and sometimes beneficial or even crucial, whereas being illogical is undesirable.

soundly but starting from different basic beliefs. So two people can both be logical but still disagree about things.

encapsulate the most important building block of logical arguments: logical implication.

for now it’s important to note that the grey area should be included somewhere, otherwise we’re just ignoring part of reality.