Brain in a vat Brain in a vat is a
thought experiment in philosophy which is premised upon the
skeptical hypothesis that one could actually be a brain in a vat receiving electrical input identical to that which would be coming from the nervous system. Similar premises are found in
Descartes's
evil demon and
dream argument. Philosopher
Hilary Putnam argues that some versions of the thought experiment would be inconsistent due to
semantic externalism. For a brain in a vat that had only ever experienced the simulated world, the statement "I'm not a brain in a vat" is true. The only possible brains and vats it could be referring to are simulated, and it is true that it is not a simulated brain in a simulated vat. By the same argument, saying "I'm a brain in a vat" would be false.
Determinism It has been argued by advocates of
libertarian free will that to call
determinism a rational statement is doubly self-defeating. • To count as rational, a belief must be
freely chosen, which according to the determinist is impossible • Any kind of debate seems to be posited on the idea that the parties involved are trying to change each other's minds.
Ethical egoism It has been argued that extreme
ethical egoism is self-defeating. Faced with a situation of limited resources, egoists would consume as much of the resource as they could, making the overall situation worse for everybody. Egoists may respond that if the situation becomes worse for everybody, the egoist will also be negatively placed, such that it is not, in fact, in the egoist's rational self-interest to take things to such extremes. However, the (unregulated)
tragedy of the commons and the (one-off)
prisoner's dilemma are cases in which, on the one hand, it is rational for an individual to seek to take as much as possible
even though to do so makes things worse for everybody,, and on the other hand, the behaviour remains rational
even though it is ultimately self-defeating. That is to say, in these cases
self-defeating does not imply
self-refuting. Egoists might respond that a tragedy of the commons assumes some degree of
public land; that is, a commons forbidding
homesteading requires regulation. Thus, an argument against the tragedy of the commons, in this belief system, is fundamentally an argument for
private property rights and the system that recognizes both property rights and
rational self-interest: capitalism. More generally, egoists might say that an increasing respect for
individual rights uniquely allows for increasing
wealth creation and increasing usable resources despite a fixed amount of
raw materials (e.g., the West pre-1776 versus post-1776, East Germany versus West Germany, Hong Kong versus mainland China, North Korea versus South Korea, etc.).
Eliminative materialism The philosopher
Mary Midgley states that the idea that
nothing exists except matter is also self-refuting because if it were true neither it, nor any other idea, would exist, and similarly that an argument to that effect would be self-refuting because it would deny its own existence. Several other philosophers also argue that
eliminative materialism is self-refuting. However, other forms of
materialism may escape this kind of argument because, rather than eliminating the
mental, they seek to
identify it with, or
reduce it to, the material. For instance,
identity theorists such as
J. J. C. Smart,
Ullin Place and
E. G. Boring state that ideas exist materially as patterns of
neural structure and activity. Christian apologist
J.P. Moreland states that such arguments are based on semantics.
Evolutionary naturalism Alvin Plantinga argues in his
evolutionary argument against naturalism that the combination of naturalism and evolution is "in a certain interesting way self-defeating" because if it were true there would be insufficient grounds to believe that human cognitive faculties are reliable. Consequently, if human cognitive abilities are unreliable, then any human construct, which by implication utilizes cognitive faculties, such as evolutionary theory, would be undermined. In this particular case, it is the confluence of evolutionary theory and naturalism that, according to the argument, undermine the reason for believing themselves to be true. Since Plantinga originally formulated the argument, a few theistic philosophers and Christian apologists have agreed. There has also been a considerable backlash of papers arguing that the argument is flawed in a number of ways, one of the more recent ones published in 2011 by Feng Ye (see also the references in the
Evolutionary argument against naturalism article).
Foundationalism The philosopher
Anthony Kenny argues that the idea, "common to theists like
Aquinas and
Descartes and to an atheist like
Russell" that "Rational belief [is] either self-evident or based directly or indirectly on what is evident" (which he termed "foundationalism" following
Plantinga) is self-refuting on the basis that this idea is itself neither self-evident nor based directly or indirectly on what is evident and that the same applies to other formulations of such foundationalism. However, the
self-evident impossibility of
infinite regress can be offered as a justification for foundationalism. Following the identification of problems with "naive foundationalism", the term is now often used to focus on
incorrigible beliefs (modern foundationalism), or
basic beliefs (
reformed foundationalism).
Philosophical skepticism Philosophical skeptics state that "nothing can be known". This has caused some to ask if nothing can be known then can that statement itself be known, or is it self-refuting. One very old response to this problem is
academic skepticism: an exception is made for the skeptic's own statement. This leads to further debate about consistency and
special pleading.
Relativism It is often stated that
relativism about
truth must be applied to itself. The cruder form of the argument concludes that since the relativist is calling relativism an absolute truth, it leads to a
contradiction. Relativists often rejoin that in fact relativism is only relatively true, leading to a subtler problem: the absolutist, the relativist's opponent, is perfectly entitled, by the relativist's
own standards, to reject relativism. That is, the relativist's arguments can have no
normative force over someone who has different
basic beliefs.
Verification and falsification principles The statements "statements are meaningless unless they can be empirically verified" and "statements are meaningless unless they can be empirically falsified" have both been called self-refuting on the basis that they can neither be empirically verified nor falsified. Similar arguments have been made for statements such as "no statements are true unless they can be shown empirically to be true", which was a problem for
logical positivism.
Moderation In All Things The perhaps ancient, proverbial saying "all things in moderation" is itself a call to excess in that it commands moderation in every single possible thing. An actually moderate assertion would be something like "most things in moderation" or more precisely, "a moderate number of things in moderation." However, many philosophers use the saying in the context of ethics. ==See also==