The mind – body prob­lem is a philo­soph­i­cal prob­lem con­cern­ing the rela­tion­ship between the human mind and body, although it can also con­cern ani­mal minds, if any, and ani­mal bod­ies. It is dis­tinct from the ques­tion of how mind and body can causal­ly inter­act, since that ques­tion pre­sup­pos­es an inter­ac­tion­ist account of mind-body rela­tions. This ques­tion aris­es when mind and body are con­sid­ered as dis­tinct, based on the premise that the mind and the body are fun­da­men­tal­ly dif­fer­ent in nature.

The mate­r­i­al con­di­tion­al (also known as mate­r­i­al impli­ca­tion, mate­r­i­al con­se­quence, or sim­ply impli­ca­tion, implies, or con­di­tion­al) is a log­i­cal con­nec­tive (or a bina­ry oper­a­tor) that is often sym­bol­ized by a for­ward arrow “→”. The mate­r­i­al con­di­tion­al is used to form state­ments of the form p → q (termed a con­di­tion­al state­ment) which is read as “if p then q”. Unlike the Eng­lish con­struc­tion “if… then…”, the mate­r­i­al con­di­tion­al state­ment p → q does not spec­i­fy a causal rela­tion­ship between p and q.

The prob­lem of induc­tion is the philo­soph­i­cal ques­tion of whether induc­tive rea­son­ing leads to knowl­edge under­stood in the clas­sic philo­soph­i­cal sense.

Essen­tial­ism is the view that every enti­ty has a set of attrib­ut­es that are nec­es­sary to its iden­ti­ty and func­tion. In ear­ly West­ern thought Plato’s ide­al­ism held that all things have such an “essence,” an “Idea” or “Form”. Like­wise, in Cat­e­gories Aris­to­tle pro­posed that all objects have a sub­stance that, as George Lakoff put it “… make the thing what it is, and with­out which it would be not that kind of thing”. The con­trary view, non-essen­tial­ism, denies the need to posit such an “essence’ ”.

Moral luck describes cir­cum­stances where­by a moral agent is assigned moral blame or praise for an action or its con­se­quences even if it is clear that said agent did not have full con­trol over either the action or its con­se­quences. This term, intro­duced by Bernard Williams, has been devel­oped, along with its sig­nif­i­cance to a coher­ent moral the­o­ry, by Williams and Thomas Nagel in their respec­tive essays on the sub­ject.

Real­ism (in phi­los­o­phy) about a giv­en object is the view that this object exists in real­i­ty inde­pen­dent­ly of our con­cep­tu­al scheme. In philo­soph­i­cal terms, these objects are onto­log­i­cal­ly inde­pen­dent of someone’s con­cep­tu­al scheme, per­cep­tions, lin­guis­tic prac­tices, beliefs, etc.

Real­ism can be applied to many philo­soph­i­cal­ly inter­est­ing objects and phe­nom­e­na: oth­er minds, the past or the future, uni­ver­sals, math­e­mat­i­cal enti­ties (such as nat­ur­al num­bers), moral cat­e­gories, the phys­i­cal world, and thought.

In epis­te­mol­o­gy, the Münch­hausen trilem­ma is a thought exper­i­ment used to demon­strate the impos­si­bil­i­ty of prov­ing any truth, even in the fields of log­ic and math­e­mat­ics. If it is asked how any knowl­edge is known to be true, proof may be pro­vid­ed. Yet that same ques­tion can be asked of the proof, and any sub­se­quent proof.

The demar­ca­tion prob­lem in the phi­los­o­phy of sci­ence is about how to dis­tin­guish between sci­ence and non-sci­ence, includ­ing between sci­ence, pseu­do­science, and oth­er prod­ucts of human activ­i­ty, like art and lit­er­a­ture, and beliefs. The debate con­tin­ues after over two mil­len­nia of dia­logue among philoso­phers of sci­ence and sci­en­tists in var­i­ous fields, and despite broad agree­ment on the basics of sci­en­tif­ic method.

A coun­ter­fac­tu­al con­di­tion­al (abbre­vi­at­ed CF), is a con­di­tion­al con­tain­ing an if-clause which is con­trary to fact. The term “coun­ter­fac­tu­al con­di­tion­al” was coined by Nel­son Good­man in 1947, extend­ing Rod­er­ick Chisholm’s (1946) notion of a “con­trary-to-fact con­di­tion­al”. The study of coun­ter­fac­tu­al spec­u­la­tion has increas­ing­ly engaged the inter­est of schol­ars in a wide range of domains such as phi­los­o­phy, human geog­ra­phy, psy­chol­o­gy, cog­ni­tive psy­chol­o­gy, his­to­ry, polit­i­cal sci­ence, eco­nom­ics, social psy­chol­o­gy, law, orga­ni­za­tion­al the­o­ry, mar­ket­ing, and epi­demi­ol­o­gy.

The ques­tion “Why is there any­thing at all?”, or, “Why is there some­thing rather than noth­ing?” has been raised or com­ment­ed on by philoso­phers includ­ing Got­tfried Wil­helm Leib­niz, Mar­tin Hei­deg­ger − who called it the fun­da­men­tal ques­tion of meta­physics − and Lud­wig Wittgen­stein. The ques­tion is gen­er­al, rather than con­cern­ing the exis­tence of any­thing spe­cif­ic such as the uni­verse/s, the Big Bang, math­e­mat­i­cal laws, phys­i­cal laws, time, con­scious­ness or God. It can be seen as an open meta­phys­i­cal ques­tion.

The hard prob­lem of con­scious­ness is the prob­lem of explain­ing how and why we have qualia or phe­nom­e­nal expe­ri­ences—how sen­sa­tions acquire char­ac­ter­is­tics, such as col­ors and tastes. The philoso­pher David Chalmers, who intro­duced the term “hard prob­lem” of con­scious­ness, con­trasts this with the “easy prob­lems” of explain­ing the abil­i­ty to dis­crim­i­nate, inte­grate infor­ma­tion, report men­tal states, focus atten­tion, etc.

The sorites para­dox (/sˈrtz/; some­times known as the para­dox of the heap) is a para­dox that aris­es from vague pred­i­cates. A typ­i­cal for­mu­la­tion involves a heap of sand, from which grains are indi­vid­u­al­ly removed. Under the assump­tion that remov­ing a sin­gle grain does not turn a heap into a non-heap, the para­dox is to con­sid­er what hap­pens when the process is repeat­ed enough times: is a sin­gle remain­ing grain still a heap? If not, when did it change from a heap to a non-heap?