a twofold reason?

Is reason divided into two areas? One which serves to draw consequences from a given set of principles, an another one which serves to question these principles, in order to show their uncertainty?

So, one of the purpose of reason would be to lead us to scepticism.

And thus, when we uphold a view, we use mainly the first area of reason, but when we come to criticize another view, we use mainly the second area.

the one that uses assumptions to form new assumptions is called deductive reasoning:

all communists are exactly like stalin
stalin was evil
all communists are evil

the one that looks at actual experiences and forms assumptions based on them is called inductive reasoning:

the sandinistas were referred to as communists but were good
zapatistas referred to as communists but were good
… (insert more valid examples than the competing argument)
the united states govt lies and communism is not evil at all, nor does it resemble the soviet union.

Hello,

   No, my distinction does not correspond to yours. What I call the first area of reason includes deductive as well as inductive reasoning.

Newer models of the mind show that we have several different information processing systems in the brain each specialized to a particular task. Each of these is fine tuned to solve a single problem. These operate mainly outside of our direct introspective awareness. So most of our active problem solving happens unconsciously.

You may have identified two of those different mental modules. There is one module that operates according to a given set of rules and operations then another model that reviews those rules.