Philosophical Arguments for the Existence of Moral Knowledge
This paper examines Renford Bambrough's philosophical argument that moral knowledge exists and is provable by parity of reasoning with knowledge of the external world. Drawing on G.E. Moore's defense of common sense and his proof of the external world, Bambrough contends that accepting evidence for an external world while simultaneously denying moral knowledge is a position of self-contradiction. The paper surveys Bambrough's responses to major objections — including arguments from cultural disagreement, the nature of moral attitudes, Hume's skepticism, unresolvable moral disputes, and Nowell-Smith's claim that objectivism leads to authoritarianism — concluding that moral knowledge rests on the same logical premises as knowledge of the physical world.
- Introduction and Thesis: Bambrough's controversial claim that moral knowledge exists
- Moore's Common Sense and the External World: Moore's commonsense proof and linguistic philosophy critique
- Parity of Reasoning: Moral Knowledge and the External World: Accepting external world implies accepting moral knowledge
- Objections to Moral Knowledge and Bambrough's Responses: Cultural disagreement, attitudes, and subjectivist objections
- Hume, Dispute Resolution, and the Limits of Skepticism: Hume's skepticism and unresolvable moral disputes addressed
- Conclusion: Moral and external-world knowledge rest on same premises
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What makes this paper effective
- It maintains a clear single-source focus, systematically unpacking the logical structure of Bambrough's argument without drifting into unrelated literature.
- It moves logically from the positive case for moral knowledge to a survey of objections, mirroring the structure of the source article and demonstrating comprehension of the dialectic.
- The surgical anesthesia example is used concisely to illustrate how Bambrough grounds abstract moral claims in intuitively undeniable propositions.
Key academic technique demonstrated
The paper demonstrates analytical summarization — the ability to faithfully reconstruct a philosopher's argument chain, including the responses to counterarguments, without collapsing nuance. Each objection Bambrough addresses (cultural disagreement, attitudinal subjectivism, Humean skepticism, unresolvability of disputes, authoritarianism) is treated as a distinct move in a debate, showing the writer understands how philosophical argumentation works through thesis, objection, and rebuttal.
Structure breakdown
The paper opens by presenting Bambrough's central thesis and its relationship to Moore's commonsense philosophy. It then explains the parity-of-reasoning argument — that accepting the external world logically commits one to accepting moral knowledge. The bulk of the paper addresses objections in sequence, and a brief conclusion restates the core logical commitment. This mirrors a standard philosophical essay structure: thesis → positive argument → objections and replies → conclusion.
Introduction and Thesis
The central idea of A Proof of the Objectivity of Morals by Renford Bambrough is the thesis that we possess moral knowledge. This is a controversial assertion, and one that is not accepted by many philosophers. Bambrough's argument connects the existence of moral knowledge to widely accepted philosophical arguments for the existence of the external world, and he contends that the two stand or fall together.
Moore's Common Sense and the External World
Bambrough opens with a consideration of two of G.E. Moore's arguments: the defence of common sense and the proof of the external world. There is evidence to support the propositions Moore makes, since any attempt to disprove knowledge that another person believes they have — such as an individual's belief that they possess two hands — means it is the contradiction itself that must be seen as erroneous. The person making such a denial must be doing so as a result of false argument or mistaken reasoning. Therefore, if we have knowledge of the external world, there is a self-evident proof that serves as a model for the existence of moral knowledge (Bambrough, 1969).
An important factor in this discussion is that Bambrough focuses on the knowledge itself rather than on the language used to express it. He argues that if a linguistic philosopher entered the discussion, that philosopher would contend that Moore used the term "know" in an unusual way (Bambrough, 1969).
Parity of Reasoning: Moral Knowledge and the External World
Looking at the argument regarding moral knowledge, Bambrough contends that to accept the evidence for the external world while simultaneously denying moral knowledge is a position of self-contradiction — yet this is a position adopted by many modern philosophers. His argument is that, by parity of reasoning, if there is an external world whose existence we accept as proven, then moral knowledge must equally be provable on the same logical basis (Bambrough, 1969).
The illustrative example offered in the paper is that we know, when a child is to undergo surgery, that an anaesthetic should be administered first, otherwise the surgery will be painful. This is a proposition that is true, and one that, Bambrough argues, could not be argued against with any reasoning that would appear credible (Bambrough, 1969).
By using the belief that one's hands exist as proof of the external world, Moore also maintains a commitment to common sense. Those who argue against moral knowledge do not accept the argument from common sense when it applies to morality, applying it only to the physical world. Furthermore, no logical explanation is given for departing from the use of common sense in the moral domain (Bambrough, 1969).
The reverse position has also been held by some philosophers: to reject the proof of the external world while accepting the moral argument. If the same standards of argument are applied consistently — given that the two support each other — this reverse position is equally self-contradictory (Bambrough, 1969).
Conclusion
When examined as a whole, the basic premise of Bambrough's argument is that accepting the evidence of the external world — and the premises on which that acceptance is based — commits one equally to accepting the arguments for moral knowledge. The two are grounded in the same logical premises, and to deny one would lead, by logical consistency, to the denial of the other.
References
Bambrough, R. (1969). A proof of the objectivity of morals. American Journal of Jurisprudence, 14, 37–53.
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