Philosophy is regarded by many as inseparable from speculation. … Philosophy has proceeded — Hans Reichenbach
I understand the gist of your speculation,’ said Rhialto. ‘It is most likely nuncupatory. — Jack Vance
Realizing how often ingenious speculation in the complex biological world has led — Thomas Hunt Morgan
As historians, we refuse to allow ourselves these vain speculations which turn — Georges-Louis Leclerc, Comte de Buffon
This general tendency to eliminate, by means of unverifiable speculations, the limits — W. R. Thompson
Let experience solve it. To listen to mere speculation in such a case were criminal. — George Washington