# Welcome to Wikipedia

,
6,739,836 articles in English

## From today's featured article

Modus ponens, one of the valid forms of inference studied in logic

Logic is the study of correct reasoning. Formal logic aims to determine the correctness of arguments based on their structure alone and often uses a formal language to analyze them. Informal logic examines arguments expressed in natural language and also takes their content and context into account. Logic distinguishes between deductive, inductive, and abductive arguments. Deductive arguments have the strongest form of support: if their premises are true then their conclusion must also be true, such as in the argument "today is Sunday; if today is Sunday then I do not have to work today; therefore I do not have to work today". Inductive arguments are generalizations, like inferring that all ravens are black based on many individual observations. Abductive arguments are inferences to the best explanation, for instance, when a doctor concludes that a patient has a certain disease that explains the symptoms they suffer. Arguments that fall short of the standards of reasoning embody fallacies. (Full article...)

Recently featured:

## Did you know ...

A bacterium that thrives in the deep ocean

## In the news

Sam Bankman-Fried

## On this day

November 5: Guy Fawkes Night in Great Britain and some Commonwealth countries (1605)

Aline Chrétien
More anniversaries:

## Today's featured picture

 Pontia edusa, also known as the eastern Bath white, is a butterfly in the family Pieridae. It is found from southeastern Europe (southern France, Italy, Corsica, Sardinia) up to central Europe and the Middle East in Iran and Iraq. It is a migrant which can also be encountered in Belgium, Holland, northern Germany and Poland, in the Baltic states and in southern Sweden and Norway. It resides in open grassy or flowery areas, in stony or rocky places and in roadsides, especially where the host plants grow, at an altitude of up to 2,300 metres (7,500 ft). This P. edusa butterfly was photographed near the Elbe in Rühstädt, Germany. Photograph credit: Sven Damerow Recently featured:

## Other areas of Wikipedia

• Community portal – The central hub for editors, with resources, links, tasks, and announcements.
• Village pump – Forum for discussions about Wikipedia itself, including policies and technical issues.
• Site news – Sources of news about Wikipedia and the broader Wikimedia movement.