4.1122
The Darwinian theory has no more to do with philosophy than has any other hypothesis of natural science.
4.113
Philosophy limits the disputable sphere of natural science.
4.114
It should limit the thinkable and thereby the unthinkable.
It should limit the unthinkable from within through the thinkable.
4.115
It will mean the unspeakable by clearly displaying the speakable.
4.116
Everything that can be thought at all can be thought clearly. Everything that can be said can be said clearly.
4.12
Propositions can represent the whole reality, but they cannot represent what they must have in common with reality in order to be able to represent it—the logical form.
To be able to represent the logical form, we should have to be able to put ourselves with the propositions outside logic, that is outside the world.
4.121
Propositions cannot represent the logical form: this mirrors itself in the propositions.
That which mirrors itself in language, language cannot represent.
That which expresses itself in language, we cannot express by language.
The propositions show the logical form of reality.
They exhibit it.
4.1211
Thus a proposition “fa” shows that in its sense the object a occurs, two propositions “fa” and “ga” that they are both about the same object.
If two propositions contradict one another, this is shown by their structure; similarly if one follows from another, etc.
4.1212
What can be shown cannot be said.