Perhaps no one who has ever lived has done everything he or she ought. But surely no ethical theory should make it impossible for someone to do everything he or she ought.
Frank Jackson and Robert Pargetter, The Philosophical Review, vol. 95, no. 2 (April, 1986), p. 242
The physical sciences—physics, chemistry, biology—tell us a great deal about what our world is like. In addition, they tell us a great deal about what we are like. They tell us what our bodies are made of, the chemical reactions necessary for life, how our ears extract location information from sound waves, the evolutionary account of how various bits of us are as they are, what causes our bodies to move through the physical environment as they do, and so on. We can think of the true, complete physical account of us as an aggregation of all there is to say about us that can be constructed from the materials to be found in the various physical sciences. This account tells the story of us as revealed by the physical sciences.
Frank Jackson, ‘Consciousness’, in Frank Jackson and Michael Smith (eds.), The Oxford Handbook of Contemporary Philosophy, New York, 2005, pp. 310-311
We think of certain departures from the principles encapsulated in probability theory, logic, decision theory, and Bayesian confirmation theory as irrational. For example, it is irrational to be more confident of the truth of a conjunction than of one of its conjuncts, and this norm corresponds to the fact that a conjunction cannot be more probable than either of its conjuncts. Should we think of departures from consequentialism principles in the same way?
Frank Jackson, ‘Departing from Consequentialism versus Departing from Decision Theory’, Behavioral and Brain Sciences, vol. 17, no. 1 (March, 1994), p. 21