The conjecture
You can make a decision in the presence of uncertainty without estimating the outcome of that decision
is an argument from ignorance, or argumentum ad ignorantiam that infers the conjecture is true from the fact that it is not proven to be false. Or alternatively, that a proposition is false because it is not proven to be true).
The argument that the absence of evidence is not evidence of absence is a form of this logical fallacy because the absence of evidence can be evidence of absence if substantial attempts to find evidence have proven negative.
This fallacy asserts that a proposition is true because it has not yet been proven false, or it is generally accepted (or vice versa).
This argument also presumes that there are only two choices: true or false. When there are other choices, including not enough investigation has been completed to choose between true or false.
A reasonable non-fallacious argument may be made that a proposition is not false because insufficient testing has been done to show it false.
Appeals to ignorance are used to shift the burden of proof to the other side. This is the classic #NoEstimates advocate approach.
I'm developing software without making estimates, and everything is just fine
However, the burden of proof is on the side that is making the assertion (#NoEstimates advocates), not on the side that disputes the assertion.
Those arguing that estimates are not needed to deliver on time, every time, need to remember
There is no principle of Microeconomics, Managerial Finance, or Probabilistic Decision making in the presence or uncertainty or scarce resources while spending other people's money that does not require an estimate to be made about the outcome of that decision, to assertain, the impact of the decision on the system of interest - usually a software development project.
No matter how many times or how loud the #Noestimates make the claim that decision can be made without estimates it's an argument from ignorance. The ignorance is those principles.
† Derived from my favorite pseudoscience debunking website Skeptical Raptor
