Deduction alone, sure. That's why you apply known truth to test the validity of it. Until it gets confirmed in a sufficient manner that's why it stays a hypothesis or theory. Without deduction you don't have science.

Without speculation and challenging of the accepted knowledge, you end up in a status quo. If you don't challenge inherited knowledge once in a while, you're vulnerable to historic lies.

The poison is in the amount and application method.

Deduction alone, sure. That's why you apply known truth to test the validity of it. Until it get confirmed in a sufficient manner that's why it stays a hypothesis or theory. Without deduction you don't have science.

Without speculation and challenging of the accepted knowledge, you end up in a status quo. If you don't challenge inherited knowledge once in a while, you're vulnerable to historic lies.

The poison is in the amount and application method.