This philosophical classic, written by G.E. Moore, has revolutionized ethical studies, as well as influenced several generations of philosophers and scientists. When I first started reading Moore’s masterpiece, I found myself amazed by his mastering of dialectics. This book does, in fact, contain the most attracting beginning I’ve ever read. It starts as follows,
“It appears to me that in Ethics, as in all other philosophical studies, the difficulties and disagreements, of which its history is full, are mainly due to a very simple cause: namely to the attempt to answer questions, without first discovering precisely what question it is which you desire to answer. I do not know how far this source of error would be done away, if philosophers would try to discover what questions they were asking, before they set about to answer it; for the work of analysis and distinction is often very difficult: we may often fail to make the necessary discovery, even though we make a definite attempt to do so. But I am inclined to think that in many cases a resolute attempt would be sufficient to ensure success; so that, if only this attempt were made, many of the most glaring difficulties and disagreements in philosophy would disappear. At all events, philosophers seem, in general, not to make the attempt; and, whether in consequence of this omission or not, they are constantly endeavoring to prove that ‘Yes’ or ‘No’ will answer questions, to which neither answer is correct, owing to the fact that what they have before their minds is not one question, but several, to some of which the true answer is ‘No’, to others ‘Yes’.
I have tried in this book to distinguish clearly two kinds of questions, which moral philosophers have always professed to answer, but which, as I have tried to shew, they have almost always confused both with one another and with other questions. These two questions may be expressed, the first in the form: What kind of things ought to exist for their own sake? the second in the form: What kind of actions ought we to perform? I have tried to shew exactly what it is that we ask about a thing, when we ask whether it ought to exist for its own sake, is good in itself or has intrinsic value; and exactly what it is that we ask about an action, when we ask whether we ought to do it, whether it is a right action or a duty.
But from a clear insight into the nature of these two questions, there appears to me to follow a second most important result: namely, what is the nature of the evidence, by which alone any ethical proposition can be proved or disproved, confirmed or rendered doubtful. Once we recognize the exact meaning of the two questions, I think it also becomes plain exactly what kind of reasons are relevant as arguments for or against any particular answer to them. It becomes plain that, for answers to the first question, no relevant evidence whatever can be adduced: from no other truth, except themselves alone, can it be inferred that they are either true or false. We can guard against error only by taking care, that, when, we try to answer a question of this kind, we have before our minds that question only, and not some other or others; but that there is great danger of such errors of confusion I have tried to shew, and also what are chief precautions by the use of which we may guard against them. As for the second question, it becomes equally plain, that any answer to it is capable of proof or disproof -that, indeed, so many different considerations are relevant to its truth or falsehood, as to make the attainment of probability very difficult, and the attainment of certainty impossible. Nevertheless the kind of evidence, which is both necessary and alone relevant to such proof and disproof, is capable of exact definition. Such evidence must contains propositions of two kinds and of two kinds only: it must consist, in the first place, of truths with regard to the results of the action in question -of causal truths- but it must also contain ethical truths of our first or self-evident class. Many truths of both kinds are necessary to the proof that any action ought to be done; and any other kind of evidence is wholly irrelevant. It follows that, if any ethical philosopher offers for propositions of the first kinds any evidence whatever, or if, for propositions of the second kind, he either fails to adduce both causal and ethical truths, or adduces truths that are neither, his reasoning has not the least tendency to establish his conclusions. But not only are his conclusions totally devoid of weight: we have, moreover, reason to suspect him of the error of confusion; since the offering of irrelevant evidence generally indicates that the philosopher who offers it has had before his mind, not the question which he professes to answer, but some other entirely different one. Ethical discussion, hitherto, has perhaps consisted chiefly in reasoning of this totally irrelevant kind.”