When considering effective approaches to AGI, one must extrapolate outwards to the types of modelling (and therefore inputs) that would be necessary to achieve any general utility. One consideration might be the fundamental "building blocks" of our physical world, and understanding the movements of these, can lead to accurate predictions of (all) occurrences. These fundamental elements are called (generally) subatomic particles and are anything but discrete values. In quantum field theory, the more accurate you are able to measure position, the less accurate you may know a quarks momentum (and vice versa). Our world, at the most fundamental layer, is probabilistic when observed. This is all not to say that an understanding of quantum mechanical kinematic descriptions is the only methodology to achieve true AGI, but to say probabilistic models, and therefore uncertainty, is a dead-end seems radically inaccurate.
That said, Dr.Minsky didn't really feel probabilistic models were dead ends. The emerging view in the field, one that Dr.Minsky urged for years, is that connectionism alone couldn't exclusively lead to AGI due to its uniformed structure. If you are unaware, connectionism is the concept of creating models around discrete units of representation (neurones in a neural net for example). You see the problem we have identified isn't that probabilistic models are inaccurate, it's that our current approach doesn't express the biological realism necessary for AGI (although sufficient for specific intelligence).
[I briefly worked with Dr.Minsky at the AI Lab before his passing last year, a hilarious man and brilliant scientist.]