Writing as a former barrister turned politician, the dictum, attributed to Keynes - "when my information changes, I change my conclusions" - is a mantra I stick by.
So too should the Government, and its respective agencies, in seeking to address the alarming picture painted by the most recent safety in custody statistics. In this case, the information can lead only to one conclusion: urgent, joined-up action is required to bring prisons back under firmer control.
This is precisely what the Justice Select Committee has recommended in its report published today on Prison Safety, calling on the Ministry of Justice (MoJ) and the National Offender Management Service (NOMS) to produce a joint action plan to tackle the factors underlying the rises in violence, self-harm and suicide in our prisons.
To flesh out these statistics, assaults rose 20% in the six months to December 2015, including 2,690 assaults against staff; in the 12 months to March 2016 there were 100 self-inflicted deaths; in 2015 the number of fires in adult prisons and young offender establishments increased by 57%, to 1,935; and the National Tactical Response Group (NTRG), who deal with the most serious of situations, including hostage taking and incidents of concerted indiscipline, are being called upon an unprecedented 30 to 40 times a month - more than once a day.
Indeed, the tragic death of Lorraine Barwell, a Serco prison officer, after being attacked last summer while escorting a prisoner from court demonstrates the need for change more powerfully than any statistic, soundbite or speech could ever achieve.
New and growing challenges, such as the influx of psychoactive substances, is exacerbating this problem, and Ministers and officials at NOMS need to grapple with the serious and deep-rooted issue of staff retention. In my visits to prisons with the Justice Committee, I see for myself the fantastic, and often unnoticed, work our dedicated prison officers carry out, but given that there are 7,000 fewer of them than in 2010, and the prison population has risen by 2,500 since then, they are fighting a losing battle.
The MoJ and NOMS have sought to improve prison safety through a wide range of legislative, operational and staff recruitment measures, including the creation of new offences of possession of psychoactive substances and knife possession in prison, as well as action to address violence, through the use of body work cameras, and to improve safeguarding procedures.
But that after a 'full throttle' recruitment programme in 2015, which saw 2,250 extra police officers recruited, net gain has only risen by 440, it is clear the intrinsic problems are still not being fully understood. That is why the Committee has recommended the creation of a joint action plan between the MoJ and NOMS, which should importantly also include plans to recruit and retain prison staff, as well as proposals on the implementation of the Corruption Prevention Strategy.
We have additionally called on the Government to publish more frequent, detailed data on a number of specific points, allowing our Committee, and the industry as a whole, to scrutinise progress and ascertain what more can be done to improve outcomes.
The Government has announced an ambitious penal reform agenda, the detail of which will become more apparent after the Queen's Speech this Wednesday. However, with all the best will in the world, the impact of these new reforms will be stunted if the fundamentals are not corrected first.
Bob Neill is the Conservative MP for Bromley and Chislehurst and chair of the justice select committee